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Updated book for master ***NO_CI***

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Juniper Bot 2020-11-07 02:32:22 +00:00
parent f42054f407
commit 3fda1ed1ed
12 changed files with 350 additions and 292 deletions
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11
master/advanced/introspection.html
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@ -162,11 +162,14 @@ result can then be converted to JSON for use with tools and libraries such as
<pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)] <pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)]
# extern crate juniper; # extern crate juniper;
# extern crate serde_json; # extern crate serde_json;
use juniper::{EmptyMutation, EmptySubscription, FieldResult, IntrospectionFormat}; use juniper::{
graphql_object, EmptyMutation, EmptySubscription, FieldResult,
GraphQLObject, IntrospectionFormat,
};
// Define our schema. // Define our schema.
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
struct Example { struct Example {
id: String, id: String,
} }
@ -176,9 +179,7 @@ impl juniper::Context for Context {}
struct Query; struct Query;
#[juniper::graphql_object( #[graphql_object(context = Context)]
Context = Context,
)]
impl Query { impl Query {
fn example(id: String) -&gt; FieldResult&lt;Example&gt; { fn example(id: String) -&gt; FieldResult&lt;Example&gt; {
unimplemented!() unimplemented!()

9
master/advanced/non_struct_objects.html
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@ -144,9 +144,10 @@ interfaces.</p>
<p>Using <code>Result</code>-like enums can be a useful way of reporting e.g. validation <p>Using <code>Result</code>-like enums can be a useful way of reporting e.g. validation
errors from a mutation:</p> errors from a mutation:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
# use juniper::{graphql_object, GraphQLObject};
# #[derive(juniper::GraphQLObject)] struct User { name: String } # #[derive(juniper::GraphQLObject)] struct User { name: String }
#
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
struct ValidationError { struct ValidationError {
field: String, field: String,
message: String, message: String,
@ -158,7 +159,7 @@ enum SignUpResult {
Error(Vec&lt;ValidationError&gt;), Error(Vec&lt;ValidationError&gt;),
} }
#[juniper::graphql_object] #[graphql_object]
impl SignUpResult { impl SignUpResult {
fn user(&amp;self) -&gt; Option&lt;&amp;User&gt; { fn user(&amp;self) -&gt; Option&lt;&amp;User&gt; {
match *self { match *self {
@ -174,7 +175,7 @@ impl SignUpResult {
} }
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>Here, we use an enum to decide whether a user's input data was valid or not, and <p>Here, we use an enum to decide whether a user's input data was valid or not, and

27
master/advanced/subscriptions.html
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@ -159,7 +159,7 @@ sequentially:</p>
# extern crate juniper; # extern crate juniper;
# extern crate juniper_subscriptions; # extern crate juniper_subscriptions;
# extern crate tokio; # extern crate tokio;
# use juniper::FieldError; # use juniper::{graphql_object, graphql_subscription, FieldError};
# use futures::Stream; # use futures::Stream;
# use std::pin::Pin; # use std::pin::Pin;
# #
@ -168,7 +168,7 @@ sequentially:</p>
# impl juniper::Context for Database {} # impl juniper::Context for Database {}
# pub struct Query; # pub struct Query;
# #[juniper::graphql_object(Context = Database)] # #[graphql_object(context = Database)]
# impl Query { # impl Query {
# fn hello_world() -&gt; &amp;str { # fn hello_world() -&gt; &amp;str {
# &quot;Hello World!&quot; # &quot;Hello World!&quot;
@ -178,7 +178,7 @@ pub struct Subscription;
type StringStream = Pin&lt;Box&lt;dyn Stream&lt;Item = Result&lt;String, FieldError&gt;&gt; + Send&gt;&gt;; type StringStream = Pin&lt;Box&lt;dyn Stream&lt;Item = Result&lt;String, FieldError&gt;&gt; + Send&gt;&gt;;
#[juniper::graphql_subscription(Context = Database)] #[graphql_subscription(context = Database)]
impl Subscription { impl Subscription {
async fn hello_world() -&gt; StringStream { async fn hello_world() -&gt; StringStream {
let stream = tokio::stream::iter(vec![ let stream = tokio::stream::iter(vec![
@ -188,6 +188,7 @@ impl Subscription {
Box::pin(stream) Box::pin(stream)
} }
} }
#
# fn main () {} # fn main () {}
</code></pre></pre> </code></pre></pre>
<a class="header" href="#coordinator" id="coordinator"><h3>Coordinator</h3></a> <a class="header" href="#coordinator" id="coordinator"><h3>Coordinator</h3></a>
@ -205,8 +206,12 @@ where [<code>Connection</code>][Connection] is a <code>Stream</code> of values r
# extern crate juniper_subscriptions; # extern crate juniper_subscriptions;
# extern crate serde_json; # extern crate serde_json;
# extern crate tokio; # extern crate tokio;
# use juniper::http::GraphQLRequest; # use juniper::{
# use juniper::{DefaultScalarValue, EmptyMutation, FieldError, RootNode, SubscriptionCoordinator}; # http::GraphQLRequest,
# graphql_object, graphql_subscription,
# DefaultScalarValue, EmptyMutation, FieldError,
# RootNode, SubscriptionCoordinator,
# };
# use juniper_subscriptions::Coordinator; # use juniper_subscriptions::Coordinator;
# use futures::{Stream, StreamExt}; # use futures::{Stream, StreamExt};
# use std::pin::Pin; # use std::pin::Pin;
@ -224,7 +229,7 @@ where [<code>Connection</code>][Connection] is a <code>Stream</code> of values r
# #
# pub struct Query; # pub struct Query;
# #
# #[juniper::graphql_object(Context = Database)] # #[graphql_object(context = Database)]
# impl Query { # impl Query {
# fn hello_world() -&gt; &amp;str { # fn hello_world() -&gt; &amp;str {
# &quot;Hello World!&quot; # &quot;Hello World!&quot;
@ -235,7 +240,7 @@ where [<code>Connection</code>][Connection] is a <code>Stream</code> of values r
# #
# type StringStream = Pin&lt;Box&lt;dyn Stream&lt;Item = Result&lt;String, FieldError&gt;&gt; + Send&gt;&gt;; # type StringStream = Pin&lt;Box&lt;dyn Stream&lt;Item = Result&lt;String, FieldError&gt;&gt; + Send&gt;&gt;;
# #
# #[juniper::graphql_subscription(Context = Database)] # #[graphql_subscription(context = Database)]
# impl Subscription { # impl Subscription {
# async fn hello_world() -&gt; StringStream { # async fn hello_world() -&gt; StringStream {
# let stream = # let stream =
@ -253,11 +258,9 @@ async fn run_subscription() {
let schema = schema(); let schema = schema();
let coordinator = Coordinator::new(schema); let coordinator = Coordinator::new(schema);
let req: GraphQLRequest&lt;DefaultScalarValue&gt; = serde_json::from_str( let req: GraphQLRequest&lt;DefaultScalarValue&gt; = serde_json::from_str(
r#&quot; r#&quot;{
{
&quot;query&quot;: &quot;subscription { helloWorld }&quot; &quot;query&quot;: &quot;subscription { helloWorld }&quot;
} }&quot;#,
&quot;#,
) )
.unwrap(); .unwrap();
let ctx = Database::new(); let ctx = Database::new();
@ -266,7 +269,7 @@ async fn run_subscription() {
println!(&quot;{}&quot;, serde_json::to_string(&amp;result).unwrap()); println!(&quot;{}&quot;, serde_json::to_string(&amp;result).unwrap());
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<a class="header" href="#web-integration-and-examples" id="web-integration-and-examples"><h3>Web Integration and Examples</h3></a> <a class="header" href="#web-integration-and-examples" id="web-integration-and-examples"><h3>Web Integration and Examples</h3></a>

299
master/print.html
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@ -200,8 +200,12 @@ types to a GraphQL schema. The most important one is the
resolvers, which you will use for the <code>Query</code> and <code>Mutation</code> roots.</p> resolvers, which you will use for the <code>Query</code> and <code>Mutation</code> roots.</p>
<pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)] <pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)]
# extern crate juniper; # extern crate juniper;
use juniper::{FieldResult, EmptySubscription}; # use std::fmt::Display;
use juniper::{
graphql_object, EmptySubscription, FieldResult, GraphQLEnum,
GraphQLInputObject, GraphQLObject, ScalarValue,
};
#
# struct DatabasePool; # struct DatabasePool;
# impl DatabasePool { # impl DatabasePool {
# fn get_connection(&amp;self) -&gt; FieldResult&lt;DatabasePool&gt; { Ok(DatabasePool) } # fn get_connection(&amp;self) -&gt; FieldResult&lt;DatabasePool&gt; { Ok(DatabasePool) }
@ -209,14 +213,14 @@ use juniper::{FieldResult, EmptySubscription};
# fn insert_human(&amp;self, _human: &amp;NewHuman) -&gt; FieldResult&lt;Human&gt; { Err(&quot;&quot;)? } # fn insert_human(&amp;self, _human: &amp;NewHuman) -&gt; FieldResult&lt;Human&gt; { Err(&quot;&quot;)? }
# } # }
#[derive(juniper::GraphQLEnum)] #[derive(GraphQLEnum)]
enum Episode { enum Episode {
NewHope, NewHope,
Empire, Empire,
Jedi, Jedi,
} }
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
#[graphql(description = &quot;A humanoid creature in the Star Wars universe&quot;)] #[graphql(description = &quot;A humanoid creature in the Star Wars universe&quot;)]
struct Human { struct Human {
id: String, id: String,
@ -227,7 +231,7 @@ struct Human {
// There is also a custom derive for mapping GraphQL input objects. // There is also a custom derive for mapping GraphQL input objects.
#[derive(juniper::GraphQLInputObject)] #[derive(GraphQLInputObject)]
#[graphql(description = &quot;A humanoid creature in the Star Wars universe&quot;)] #[graphql(description = &quot;A humanoid creature in the Star Wars universe&quot;)]
struct NewHuman { struct NewHuman {
name: String, name: String,
@ -250,14 +254,13 @@ impl juniper::Context for Context {}
struct Query; struct Query;
#[juniper::graphql_object( #[graphql_object(
// Here we specify the context type for the object. // Here we specify the context type for the object.
// We need to do this in every type that // We need to do this in every type that
// needs access to the context. // needs access to the context.
Context = Context, context = Context,
)] )]
impl Query { impl Query {
fn apiVersion() -&gt; &amp;str { fn apiVersion() -&gt; &amp;str {
&quot;1.0&quot; &quot;1.0&quot;
} }
@ -281,14 +284,18 @@ impl Query {
struct Mutation; struct Mutation;
#[juniper::graphql_object( #[graphql_object(
Context = Context, context = Context,
)]
impl Mutation {
fn createHuman(context: &amp;Context, new_human: NewHuman) -&gt; FieldResult&lt;Human&gt; { // If we need to use `ScalarValue` parametrization explicitly somewhere
let db = context.pool.get_connection()?; // in the object definition (like here in `FieldResult`), we should
let human: Human = db.insert_human(&amp;new_human)?; // declare an explicit type parameter for that, and specify it.
scalar = S,
)]
impl&lt;S: ScalarValue + Display&gt; Mutation {
fn createHuman(context: &amp;Context, new_human: NewHuman) -&gt; FieldResult&lt;Human, S&gt; {
let db = context.pool.get_connection().map_err(|e| e.map_scalar_value())?;
let human: Human = db.insert_human(&amp;new_human).map_err(|e| e.map_scalar_value())?;
Ok(human) Ok(human)
} }
} }
@ -296,7 +303,7 @@ impl Mutation {
// A root schema consists of a query, a mutation, and a subscription. // A root schema consists of a query, a mutation, and a subscription.
// Request queries can be executed against a RootNode. // Request queries can be executed against a RootNode.
type Schema = juniper::RootNode&lt;'static, Query, Mutation, EmptySubscription&lt;Context&gt;&gt;; type Schema = juniper::RootNode&lt;'static, Query, Mutation, EmptySubscription&lt;Context&gt;&gt;;
#
# fn main() { # fn main() {
# let _ = Schema::new(Query, Mutation{}, EmptySubscription::new()); # let _ = Schema::new(Query, Mutation{}, EmptySubscription::new());
# } # }
@ -308,10 +315,12 @@ type Schema = juniper::RootNode&lt;'static, Query, Mutation, EmptySubscription&l
<p>You can invoke <code>juniper::execute</code> directly to run a GraphQL query:</p> <p>You can invoke <code>juniper::execute</code> directly to run a GraphQL query:</p>
<pre><pre class="playpen"><code class="language-rust"># // Only needed due to 2018 edition because the macro is not accessible. <pre><pre class="playpen"><code class="language-rust"># // Only needed due to 2018 edition because the macro is not accessible.
# #[macro_use] extern crate juniper; # #[macro_use] extern crate juniper;
use juniper::{FieldResult, Variables, EmptyMutation, EmptySubscription}; use juniper::{
graphql_object, EmptyMutation, EmptySubscription, FieldResult,
GraphQLEnum, Variables,
};
#[derive(GraphQLEnum, Clone, Copy)]
#[derive(juniper::GraphQLEnum, Clone, Copy)]
enum Episode { enum Episode {
NewHope, NewHope,
Empire, Empire,
@ -325,16 +334,13 @@ impl juniper::Context for Ctx {}
struct Query; struct Query;
#[juniper::graphql_object( #[graphql_object(context = Ctx)]
Context = Ctx,
)]
impl Query { impl Query {
fn favoriteEpisode(context: &amp;Ctx) -&gt; FieldResult&lt;Episode&gt; { fn favoriteEpisode(context: &amp;Ctx) -&gt; FieldResult&lt;Episode&gt; {
Ok(context.0) Ok(context.0)
} }
} }
// A root schema consists of a query, a mutation, and a subscription. // A root schema consists of a query, a mutation, and a subscription.
// Request queries can be executed against a RootNode. // Request queries can be executed against a RootNode.
type Schema = juniper::RootNode&lt;'static, Query, EmptyMutation&lt;Ctx&gt;, EmptySubscription&lt;Ctx&gt;&gt;; type Schema = juniper::RootNode&lt;'static, Query, EmptyMutation&lt;Ctx&gt;, EmptySubscription&lt;Ctx&gt;&gt;;
@ -393,12 +399,13 @@ struct you want to expose, the easiest way is to use the custom derive
attribute. The other way is described in the <a href="complex_fields.html">Complex fields</a> attribute. The other way is described in the <a href="complex_fields.html">Complex fields</a>
chapter.</p> chapter.</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>This will create a GraphQL object type called <code>Person</code>, with two fields: <code>name</code> <p>This will create a GraphQL object type called <code>Person</code>, with two fields: <code>name</code>
@ -411,7 +418,8 @@ fields. Juniper will automatically use associated doc comments as GraphQL
descriptions:</p> descriptions:</p>
<p>!FILENAME GraphQL descriptions via Rust doc comments</p> <p>!FILENAME GraphQL descriptions via Rust doc comments</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
/// Information about a person /// Information about a person
struct Person { struct Person {
/// The person's full name, including both first and last names /// The person's full name, including both first and last names
@ -419,14 +427,15 @@ struct Person {
/// The person's age in years, rounded down /// The person's age in years, rounded down
age: i32, age: i32,
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>Objects and fields without doc comments can instead set a <code>description</code> <p>Objects and fields without doc comments can instead set a <code>description</code>
via the <code>graphql</code> attribute. The following example is equivalent to the above:</p> via the <code>graphql</code> attribute. The following example is equivalent to the above:</p>
<p>!FILENAME GraphQL descriptions via attribute</p> <p>!FILENAME GraphQL descriptions via attribute</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
#[graphql(description = &quot;Information about a person&quot;)] #[graphql(description = &quot;Information about a person&quot;)]
struct Person { struct Person {
#[graphql(description = &quot;The person's full name, including both first and last names&quot;)] #[graphql(description = &quot;The person's full name, including both first and last names&quot;)]
@ -434,14 +443,15 @@ struct Person {
#[graphql(description = &quot;The person's age in years, rounded down&quot;)] #[graphql(description = &quot;The person's age in years, rounded down&quot;)]
age: i32, age: i32,
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>Descriptions set via the <code>graphql</code> attribute take precedence over Rust <p>Descriptions set via the <code>graphql</code> attribute take precedence over Rust
doc comments. This enables internal Rust documentation and external GraphQL doc comments. This enables internal Rust documentation and external GraphQL
documentation to differ:</p> documentation to differ:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
#[graphql(description = &quot;This description shows up in GraphQL&quot;)] #[graphql(description = &quot;This description shows up in GraphQL&quot;)]
/// This description shows up in RustDoc /// This description shows up in RustDoc
struct Person { struct Person {
@ -451,7 +461,7 @@ struct Person {
/// This description shows up in both RustDoc and GraphQL /// This description shows up in both RustDoc and GraphQL
age: i32, age: i32,
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<a class="header" href="#relationships" id="relationships"><h2>Relationships</h2></a> <a class="header" href="#relationships" id="relationships"><h2>Relationships</h2></a>
@ -470,18 +480,19 @@ or</li>
</ul> </ul>
<p>Let's see what that means for building relationships between objects:</p> <p>Let's see what that means for building relationships between objects:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
} }
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
struct House { struct House {
address: Option&lt;String&gt;, // Converted into String (nullable) address: Option&lt;String&gt;, // Converted into String (nullable)
inhabitants: Vec&lt;Person&gt;, // Converted into [Person!]! inhabitants: Vec&lt;Person&gt;, // Converted into [Person!]!
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>Because <code>Person</code> is a valid GraphQL type, you can have a <code>Vec&lt;Person&gt;</code> in a <p>Because <code>Person</code> is a valid GraphQL type, you can have a <code>Vec&lt;Person&gt;</code> in a
@ -491,39 +502,42 @@ objects.</p>
<p>By default, struct fields are converted from Rust's standard <code>snake_case</code> naming <p>By default, struct fields are converted from Rust's standard <code>snake_case</code> naming
convention into GraphQL's <code>camelCase</code> convention:</p> convention into GraphQL's <code>camelCase</code> convention:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
struct Person { struct Person {
first_name: String, // Would be exposed as firstName in the GraphQL schema first_name: String, // Would be exposed as firstName in the GraphQL schema
last_name: String, // Exposed as lastName last_name: String, // Exposed as lastName
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>You can override the name by using the <code>graphql</code> attribute on individual struct <p>You can override the name by using the <code>graphql</code> attribute on individual struct
fields:</p> fields:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
#[graphql(name = &quot;websiteURL&quot;)] #[graphql(name = &quot;websiteURL&quot;)]
website_url: Option&lt;String&gt;, // Now exposed as websiteURL in the schema website_url: Option&lt;String&gt;, // Now exposed as websiteURL in the schema
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<a class="header" href="#deprecating-fields" id="deprecating-fields"><h2>Deprecating fields</h2></a> <a class="header" href="#deprecating-fields" id="deprecating-fields"><h2>Deprecating fields</h2></a>
<p>To deprecate a field, you specify a deprecation reason using the <code>graphql</code> <p>To deprecate a field, you specify a deprecation reason using the <code>graphql</code>
attribute:</p> attribute:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
#[graphql(deprecated = &quot;Please use the name field instead&quot;)] #[graphql(deprecated = &quot;Please use the name field instead&quot;)]
first_name: String, first_name: String,
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>The <code>name</code>, <code>description</code>, and <code>deprecation</code> arguments can of course be <p>The <code>name</code>, <code>description</code>, and <code>deprecation</code> arguments can of course be
@ -532,7 +546,8 @@ only deprecate object fields and enum values.</p>
<a class="header" href="#skipping-fields" id="skipping-fields"><h2>Skipping fields</h2></a> <a class="header" href="#skipping-fields" id="skipping-fields"><h2>Skipping fields</h2></a>
<p>By default all fields in a <code>GraphQLObject</code> are included in the generated GraphQL type. To prevent including a specific field, annotate the field with <code>#[graphql(skip)]</code>:</p> <p>By default all fields in a <code>GraphQLObject</code> are included in the generated GraphQL type. To prevent including a specific field, annotate the field with <code>#[graphql(skip)]</code>:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
@ -540,13 +555,13 @@ struct Person {
# #[allow(dead_code)] # #[allow(dead_code)]
password_hash: String, // This cannot be queried or modified from GraphQL password_hash: String, // This cannot be queried or modified from GraphQL
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<a class="header" href="#complex-fields" id="complex-fields"><h1>Complex fields</h1></a> <a class="header" href="#complex-fields" id="complex-fields"><h1>Complex fields</h1></a>
<p>If you've got a struct that can't be mapped directly to GraphQL, that contains <p>If you've got a struct that can't be mapped directly to GraphQL, that contains
computed fields or circular structures, you have to use a more powerful tool: computed fields or circular structures, you have to use a more powerful tool:
the <code>object</code> procedural macro. This macro lets you define GraphQL object the <code>#[graphql_object]</code> procedural macro. This macro lets you define GraphQL object
fields in a Rust <code>impl</code> block for a type. Note that only GraphQL fields fields in a Rust <code>impl</code> block for a type. Note that only GraphQL fields
can be specified in this <code>impl</code> block. If you want to define normal methods on the struct, can be specified in this <code>impl</code> block. If you want to define normal methods on the struct,
you have to do so in a separate, normal <code>impl</code> block. Continuing with the you have to do so in a separate, normal <code>impl</code> block. Continuing with the
@ -554,13 +569,14 @@ example from the last chapter, this is how you would define <code>Person</code>
macro:</p> macro:</p>
<pre><pre class="playpen"><code class="language-rust"># #![allow(dead_code)] <pre><pre class="playpen"><code class="language-rust"># #![allow(dead_code)]
# extern crate juniper; # extern crate juniper;
# use juniper::graphql_object;
# #
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
} }
#[juniper::graphql_object] #[graphql_object]
impl Person { impl Person {
fn name(&amp;self) -&gt; &amp;str { fn name(&amp;self) -&gt; &amp;str {
self.name.as_str() self.name.as_str()
@ -578,13 +594,15 @@ impl Person {
// [...] // [...]
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<p>While this is a bit more verbose, it lets you write any kind of function in the <p>While this is a bit more verbose, it lets you write any kind of function in the
field resolver. With this syntax, fields can also take arguments:</p> field resolver. With this syntax, fields can also take arguments:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::{graphql_object, GraphQLObject};
#
#[derive(GraphQLObject)]
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
@ -594,14 +612,14 @@ struct House {
inhabitants: Vec&lt;Person&gt;, inhabitants: Vec&lt;Person&gt;,
} }
#[juniper::graphql_object] #[graphql_object]
impl House { impl House {
// Creates the field inhabitantWithName(name), returning a nullable person // Creates the field inhabitantWithName(name), returning a nullable person
fn inhabitant_with_name(&amp;self, name: String) -&gt; Option&lt;&amp;Person&gt; { fn inhabitant_with_name(&amp;self, name: String) -&gt; Option&lt;&amp;Person&gt; {
self.inhabitants.iter().find(|p| p.name == name) self.inhabitants.iter().find(|p| p.name == name)
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>To access global data such as database connections or authentication <p>To access global data such as database connections or authentication
@ -612,20 +630,20 @@ chapter: <a href="using_contexts.html">Using contexts</a>.</p>
to <code>camelCase</code>. If you need to override the conversion, you can simply rename to <code>camelCase</code>. If you need to override the conversion, you can simply rename
the field. Also, the type name can be changed with an alias:</p> the field. Also, the type name can be changed with an alias:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
# use juniper::graphql_object;
struct Person { #
} struct Person;
/// Doc comments are used as descriptions for GraphQL. /// Doc comments are used as descriptions for GraphQL.
#[juniper::graphql_object( #[graphql_object(
// With this attribute you can change the public GraphQL name of the type. // With this attribute you can change the public GraphQL name of the type.
name = &quot;PersonObject&quot;, name = &quot;PersonObject&quot;,
// You can also specify a description here, which will overwrite // You can also specify a description here, which will overwrite
// a doc comment description. // a doc comment description.
description = &quot;...&quot;, description = &quot;...&quot;,
)] )]
impl Person { impl Person {
/// A doc comment on the field will also be used for GraphQL. /// A doc comment on the field will also be used for GraphQL.
#[graphql( #[graphql(
// Or provide a description here. // Or provide a description here.
@ -636,9 +654,7 @@ impl Person {
} }
// Fields can also be renamed if required. // Fields can also be renamed if required.
#[graphql( #[graphql(name = &quot;myCustomFieldName&quot;)]
name = &quot;myCustomFieldName&quot;,
)]
fn renamed_field() -&gt; bool { fn renamed_field() -&gt; bool {
true true
} }
@ -655,7 +671,7 @@ impl Person {
true true
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<a class="header" href="#customizing-arguments" id="customizing-arguments"><h2>Customizing arguments</h2></a> <a class="header" href="#customizing-arguments" id="customizing-arguments"><h2>Customizing arguments</h2></a>
@ -664,10 +680,11 @@ impl Person {
<p><strong>Note</strong>: The syntax for this is currently a little awkward. <p><strong>Note</strong>: The syntax for this is currently a little awkward.
This will become better once the <a href="https://github.com/rust-lang/rust/issues/60406">Rust RFC 2565</a> is implemented.</p> This will become better once the <a href="https://github.com/rust-lang/rust/issues/60406">Rust RFC 2565</a> is implemented.</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
# use juniper::graphql_object;
#
struct Person {} struct Person {}
#[juniper::graphql_object] #[graphql_object]
impl Person { impl Person {
#[graphql( #[graphql(
arguments( arguments(
@ -687,7 +704,7 @@ impl Person {
format!(&quot;{} {}&quot;, arg1, arg2) format!(&quot;{} {}&quot;, arg1, arg2)
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<a class="header" href="#more-features" id="more-features"><h2>More features</h2></a> <a class="header" href="#more-features" id="more-features"><h2>More features</h2></a>
@ -697,7 +714,7 @@ impl Person {
<li>Per-argument default values</li> <li>Per-argument default values</li>
<li>Per-argument descriptions</li> <li>Per-argument descriptions</li>
</ul> </ul>
<p>These, and more features, are described more thorougly in <a href="https://docs.rs/juniper/latest/juniper/macro.object.html">the reference <p>These, and more features, are described more thoroughly in <a href="https://docs.rs/juniper/latest/juniper/macro.object.html">the reference
documentation</a>.</p> documentation</a>.</p>
<a class="header" href="#using-contexts" id="using-contexts"><h1>Using contexts</h1></a> <a class="header" href="#using-contexts" id="using-contexts"><h1>Using contexts</h1></a>
<p>The context type is a feature in Juniper that lets field resolvers access global <p>The context type is a feature in Juniper that lets field resolvers access global
@ -710,7 +727,7 @@ integration.</p>
resolvers. Let's say that we have a simple user database in a <code>HashMap</code>:</p> resolvers. Let's say that we have a simple user database in a <code>HashMap</code>:</p>
<pre><pre class="playpen"><code class="language-rust"># #![allow(dead_code)] <pre><pre class="playpen"><code class="language-rust"># #![allow(dead_code)]
# use std::collections::HashMap; # use std::collections::HashMap;
#
struct Database { struct Database {
users: HashMap&lt;i32, User&gt;, users: HashMap&lt;i32, User&gt;,
} }
@ -720,7 +737,7 @@ struct User {
name: String, name: String,
friend_ids: Vec&lt;i32&gt;, friend_ids: Vec&lt;i32&gt;,
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<p>We would like a <code>friends</code> field on <code>User</code> that returns a list of <code>User</code> objects. <p>We would like a <code>friends</code> field on <code>User</code> that returns a list of <code>User</code> objects.
@ -729,9 +746,10 @@ In order to write such a field though, the database must be queried.</p>
the user object.</p> the user object.</p>
<p>To gain access to the context, we need to specify an argument with the same <p>To gain access to the context, we need to specify an argument with the same
type as the specified <code>Context</code> for the type:</p> type as the specified <code>Context</code> for the type:</p>
<pre><pre class="playpen"><code class="language-rust"># use std::collections::HashMap; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
extern crate juniper; # use std::collections::HashMap;
# use juniper::graphql_object;
#
// This struct represents our context. // This struct represents our context.
struct Database { struct Database {
users: HashMap&lt;i32, User&gt;, users: HashMap&lt;i32, User&gt;,
@ -746,11 +764,8 @@ struct User {
friend_ids: Vec&lt;i32&gt;, friend_ids: Vec&lt;i32&gt;,
} }
// Assign Database as the context type for User // Assign Database as the context type for User
#[juniper::graphql_object( #[graphql_object(context = Database)]
Context = Database,
)]
impl User { impl User {
// 3. Inject the context by specifying an argument // 3. Inject the context by specifying an argument
// with the context type. // with the context type.
@ -773,7 +788,7 @@ impl User {
self.id self.id
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<p>You only get an immutable reference to the context, so if you want to affect <p>You only get an immutable reference to the context, so if you want to affect
@ -804,13 +819,13 @@ use std::{
fs::{File}, fs::{File},
io::{Read}, io::{Read},
}; };
use juniper::FieldResult; use juniper::{graphql_object, FieldResult};
struct Example { struct Example {
filename: PathBuf, filename: PathBuf,
} }
#[juniper::graphql_object] #[graphql_object]
impl Example { impl Example {
fn contents() -&gt; FieldResult&lt;String&gt; { fn contents() -&gt; FieldResult&lt;String&gt; {
let mut file = File::open(&amp;self.filename)?; let mut file = File::open(&amp;self.filename)?;
@ -829,7 +844,7 @@ impl Example {
} }
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p><code>FieldResult&lt;T&gt;</code> is an alias for <code>Result&lt;T, FieldError&gt;</code>, which is the error <p><code>FieldResult&lt;T&gt;</code> is an alias for <code>Result&lt;T, FieldError&gt;</code>, which is the error
@ -889,14 +904,16 @@ following would be returned:</p>
<p>Sometimes it is desirable to return additional structured error information <p>Sometimes it is desirable to return additional structured error information
to clients. This can be accomplished by implementing <a href="https://docs.rs/juniper/latest/juniper/trait.IntoFieldError.html"><code>IntoFieldError</code></a>:</p> to clients. This can be accomplished by implementing <a href="https://docs.rs/juniper/latest/juniper/trait.IntoFieldError.html"><code>IntoFieldError</code></a>:</p>
<pre><pre class="playpen"><code class="language-rust"># #[macro_use] extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># #[macro_use] extern crate juniper;
# use juniper::{graphql_object, FieldError, IntoFieldError, ScalarValue};
#
enum CustomError { enum CustomError {
WhateverNotSet, WhateverNotSet,
} }
impl juniper::IntoFieldError for CustomError { impl&lt;S: ScalarValue&gt; IntoFieldError&lt;S&gt; for CustomError {
fn into_field_error(self) -&gt; juniper::FieldError { fn into_field_error(self) -&gt; FieldError&lt;S&gt; {
match self { match self {
CustomError::WhateverNotSet =&gt; juniper::FieldError::new( CustomError::WhateverNotSet =&gt; FieldError::new(
&quot;Whatever does not exist&quot;, &quot;Whatever does not exist&quot;,
graphql_value!({ graphql_value!({
&quot;type&quot;: &quot;NO_WHATEVER&quot; &quot;type&quot;: &quot;NO_WHATEVER&quot;
@ -910,7 +927,7 @@ struct Example {
whatever: Option&lt;bool&gt;, whatever: Option&lt;bool&gt;,
} }
#[juniper::graphql_object] #[graphql_object]
impl Example { impl Example {
fn whatever() -&gt; Result&lt;bool, CustomError&gt; { fn whatever() -&gt; Result&lt;bool, CustomError&gt; {
if let Some(value) = self.whatever { if let Some(value) = self.whatever {
@ -919,18 +936,18 @@ impl Example {
Err(CustomError::WhateverNotSet) Err(CustomError::WhateverNotSet)
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>The specified structured error information is included in the <a href="https://facebook.github.io/graphql/June2018/#sec-Errors"><code>extensions</code></a> key:</p> <p>The specified structured error information is included in the <a href="https://facebook.github.io/graphql/June2018/#sec-Errors"><code>extensions</code></a> key:</p>
<pre><code class="language-js">{ <pre><code class="language-json">{
&quot;errors&quot;: [ &quot;errors&quot;: [{
&quot;message&quot;: &quot;Whatever does not exist&quot;, &quot;message&quot;: &quot;Whatever does not exist&quot;,
&quot;locations&quot;: [{ &quot;line&quot;: 2, &quot;column&quot;: 4 }]), &quot;locations&quot;: [{&quot;line&quot;: 2, &quot;column&quot;: 4}],
&quot;extensions&quot;: { &quot;extensions&quot;: {
&quot;type&quot;: &quot;NO_WHATEVER&quot; &quot;type&quot;: &quot;NO_WHATEVER&quot;
} }
] }]
} }
</code></pre> </code></pre>
<a class="header" href="#errors-backed-by-graphqls-schema" id="errors-backed-by-graphqls-schema"><h2>Errors Backed by GraphQL's Schema</h2></a> <a class="header" href="#errors-backed-by-graphqls-schema" id="errors-backed-by-graphqls-schema"><h2>Errors Backed by GraphQL's Schema</h2></a>
@ -952,24 +969,26 @@ for a particular field are also returned as a string. In this example
the string contains a server-side localized error message. However, it is also the string contains a server-side localized error message. However, it is also
possible to return a unique string identifier and have the client present a localized string to the user.</p> possible to return a unique string identifier and have the client present a localized string to the user.</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::{graphql_object, GraphQLObject, GraphQLUnion};
#
#[derive(GraphQLObject)]
pub struct Item { pub struct Item {
name: String, name: String,
quantity: i32, quantity: i32,
} }
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
pub struct ValidationError { pub struct ValidationError {
field: String, field: String,
message: String, message: String,
} }
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
pub struct ValidationErrors { pub struct ValidationErrors {
errors: Vec&lt;ValidationError&gt;, errors: Vec&lt;ValidationError&gt;,
} }
#[derive(juniper::GraphQLUnion)] #[derive(GraphQLUnion)]
pub enum GraphQLResult { pub enum GraphQLResult {
Ok(Item), Ok(Item),
Err(ValidationErrors), Err(ValidationErrors),
@ -977,7 +996,7 @@ pub enum GraphQLResult {
pub struct Mutation; pub struct Mutation;
#[juniper::graphql_object] #[graphql_object]
impl Mutation { impl Mutation {
fn addItem(&amp;self, name: String, quantity: i32) -&gt; GraphQLResult { fn addItem(&amp;self, name: String, quantity: i32) -&gt; GraphQLResult {
let mut errors = Vec::new(); let mut errors = Vec::new();
@ -1003,7 +1022,7 @@ impl Mutation {
} }
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>Each function may have a different return type and depending on the input <p>Each function may have a different return type and depending on the input
@ -1039,19 +1058,21 @@ field is set if the validation for that particular field fails. You will likely
before. Each resolver function has a custom <code>ValidationResult</code> which before. Each resolver function has a custom <code>ValidationResult</code> which
contains only fields provided by the function.</p> contains only fields provided by the function.</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::{graphql_object, GraphQLObject, GraphQLUnion};
#
#[derive(GraphQLObject)]
pub struct Item { pub struct Item {
name: String, name: String,
quantity: i32, quantity: i32,
} }
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
pub struct ValidationError { pub struct ValidationError {
name: Option&lt;String&gt;, name: Option&lt;String&gt;,
quantity: Option&lt;String&gt;, quantity: Option&lt;String&gt;,
} }
#[derive(juniper::GraphQLUnion)] #[derive(GraphQLUnion)]
pub enum GraphQLResult { pub enum GraphQLResult {
Ok(Item), Ok(Item),
Err(ValidationError), Err(ValidationError),
@ -1059,7 +1080,7 @@ pub enum GraphQLResult {
pub struct Mutation; pub struct Mutation;
#[juniper::graphql_object] #[graphql_object]
impl Mutation { impl Mutation {
fn addItem(&amp;self, name: String, quantity: i32) -&gt; GraphQLResult { fn addItem(&amp;self, name: String, quantity: i32) -&gt; GraphQLResult {
let mut error = ValidationError { let mut error = ValidationError {
@ -1082,7 +1103,7 @@ impl Mutation {
} }
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<pre><code class="language-graphql">{ <pre><code class="language-graphql">{
@ -1108,22 +1129,23 @@ errors when they occur.</p>
<p>In the following example, a theoretical database could fail <p>In the following example, a theoretical database could fail
and would generate errors. Since it is not common for the database to and would generate errors. Since it is not common for the database to
fail, the corresponding error is returned as a critical error:</p> fail, the corresponding error is returned as a critical error:</p>
<pre><pre class="playpen"><code class="language-rust"># // Only needed due to 2018 edition because the macro is not accessible. <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
# #[macro_use] extern crate juniper; #
use juniper::{graphql_object, graphql_value, FieldError, GraphQLObject, GraphQLUnion, ScalarValue};
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
pub struct Item { pub struct Item {
name: String, name: String,
quantity: i32, quantity: i32,
} }
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
pub struct ValidationErrorItem { pub struct ValidationErrorItem {
name: Option&lt;String&gt;, name: Option&lt;String&gt;,
quantity: Option&lt;String&gt;, quantity: Option&lt;String&gt;,
} }
#[derive(juniper::GraphQLUnion)] #[derive(GraphQLUnion)]
pub enum GraphQLResult { pub enum GraphQLResult {
Ok(Item), Ok(Item),
Err(ValidationErrorItem), Err(ValidationErrorItem),
@ -1133,10 +1155,10 @@ pub enum ApiError {
Database, Database,
} }
impl juniper::IntoFieldError for ApiError { impl&lt;S: ScalarValue&gt; juniper::IntoFieldError&lt;S&gt; for ApiError {
fn into_field_error(self) -&gt; juniper::FieldError { fn into_field_error(self) -&gt; FieldError&lt;S&gt; {
match self { match self {
ApiError::Database =&gt; juniper::FieldError::new( ApiError::Database =&gt; FieldError::new(
&quot;Internal database error&quot;, &quot;Internal database error&quot;,
graphql_value!({ graphql_value!({
&quot;type&quot;: &quot;DATABASE&quot; &quot;type&quot;: &quot;DATABASE&quot;
@ -1148,7 +1170,7 @@ impl juniper::IntoFieldError for ApiError {
pub struct Mutation; pub struct Mutation;
#[juniper::graphql_object] #[graphql_object]
impl Mutation { impl Mutation {
fn addItem(&amp;self, name: String, quantity: i32) -&gt; Result&lt;GraphQLResult, ApiError&gt; { fn addItem(&amp;self, name: String, quantity: i32) -&gt; Result&lt;GraphQLResult, ApiError&gt; {
let mut error = ValidationErrorItem { let mut error = ValidationErrorItem {
@ -1171,7 +1193,7 @@ impl Mutation {
} }
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<a class="header" href="#additional-material" id="additional-material"><h2>Additional Material</h2></a> <a class="header" href="#additional-material" id="additional-material"><h2>Additional Material</h2></a>
@ -2265,18 +2287,18 @@ object somewhere but never reference it, it will not be exposed in a schema.</p>
object in Juniper, most commonly using the <code>graphql_object</code> proc macro:</p> object in Juniper, most commonly using the <code>graphql_object</code> proc macro:</p>
<pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)] <pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)]
# extern crate juniper; # extern crate juniper;
# use juniper::FieldResult; # use juniper::{graphql_object, FieldResult, GraphQLObject};
# #[derive(juniper::GraphQLObject)] struct User { name: String } # #[derive(GraphQLObject)] struct User { name: String }
struct Root; struct Root;
#[juniper::graphql_object] #[graphql_object]
impl Root { impl Root {
fn userWithUsername(username: String) -&gt; FieldResult&lt;Option&lt;User&gt;&gt; { fn userWithUsername(username: String) -&gt; FieldResult&lt;Option&lt;User&gt;&gt; {
// Look up user in database... // Look up user in database...
# unimplemented!() # unimplemented!()
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<a class="header" href="#mutations" id="mutations"><h2>Mutations</h2></a> <a class="header" href="#mutations" id="mutations"><h2>Mutations</h2></a>
@ -2284,28 +2306,30 @@ impl Root {
that performs some mutating side-effect such as updating a database.</p> that performs some mutating side-effect such as updating a database.</p>
<pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)] <pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)]
# extern crate juniper; # extern crate juniper;
# use juniper::FieldResult; # use juniper::{graphql_object, FieldResult, GraphQLObject};
# #[derive(juniper::GraphQLObject)] struct User { name: String } # #[derive(GraphQLObject)] struct User { name: String }
struct Mutations; struct Mutations;
#[juniper::graphql_object] #[graphql_object]
impl Mutations { impl Mutations {
fn signUpUser(name: String, email: String) -&gt; FieldResult&lt;User&gt; { fn signUpUser(name: String, email: String) -&gt; FieldResult&lt;User&gt; {
// Validate inputs and save user in database... // Validate inputs and save user in database...
# unimplemented!() # unimplemented!()
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<a class="header" href="#converting-a-rust-schema-to-the-a-hrefhttpsgraphqlorglearnschematype-languagegraphql-schema-languagea" id="converting-a-rust-schema-to-the-a-hrefhttpsgraphqlorglearnschematype-languagegraphql-schema-languagea"><h1>Converting a Rust schema to the <a href="https://graphql.org/learn/schema/#type-language">GraphQL Schema Language</a></h1></a> <a class="header" href="#converting-a-rust-schema-to-the-a-hrefhttpsgraphqlorglearnschematype-languagegraphql-schema-languagea" id="converting-a-rust-schema-to-the-a-hrefhttpsgraphqlorglearnschematype-languagegraphql-schema-languagea"><h1>Converting a Rust schema to the <a href="https://graphql.org/learn/schema/#type-language">GraphQL Schema Language</a></h1></a>
<p>Many tools in the GraphQL ecosystem require the schema to be defined in the <a href="https://graphql.org/learn/schema/#type-language">GraphQL Schema Language</a>. You can generate a <a href="https://graphql.org/learn/schema/#type-language">GraphQL Schema Language</a> representation of your schema defined in Rust using the <code>schema-language</code> feature (on by default):</p> <p>Many tools in the GraphQL ecosystem require the schema to be defined in the <a href="https://graphql.org/learn/schema/#type-language">GraphQL Schema Language</a>. You can generate a <a href="https://graphql.org/learn/schema/#type-language">GraphQL Schema Language</a> representation of your schema defined in Rust using the <code>schema-language</code> feature (on by default):</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
use juniper::{FieldResult, EmptyMutation, EmptySubscription, RootNode}; use juniper::{
graphql_object, EmptyMutation, EmptySubscription, FieldResult, RootNode,
};
struct Query; struct Query;
#[juniper::graphql_object] #[graphql_object]
impl Query { impl Query {
fn hello(&amp;self) -&gt; FieldResult&lt;&amp;str&gt; { fn hello(&amp;self) -&gt; FieldResult&lt;&amp;str&gt; {
Ok(&quot;hello world&quot;) Ok(&quot;hello world&quot;)
@ -2553,11 +2577,14 @@ result can then be converted to JSON for use with tools and libraries such as
<pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)] <pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)]
# extern crate juniper; # extern crate juniper;
# extern crate serde_json; # extern crate serde_json;
use juniper::{EmptyMutation, EmptySubscription, FieldResult, IntrospectionFormat}; use juniper::{
graphql_object, EmptyMutation, EmptySubscription, FieldResult,
GraphQLObject, IntrospectionFormat,
};
// Define our schema. // Define our schema.
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
struct Example { struct Example {
id: String, id: String,
} }
@ -2567,9 +2594,7 @@ impl juniper::Context for Context {}
struct Query; struct Query;
#[juniper::graphql_object( #[graphql_object(context = Context)]
Context = Context,
)]
impl Query { impl Query {
fn example(id: String) -&gt; FieldResult&lt;Example&gt; { fn example(id: String) -&gt; FieldResult&lt;Example&gt; {
unimplemented!() unimplemented!()
@ -2607,9 +2632,10 @@ interfaces.</p>
<p>Using <code>Result</code>-like enums can be a useful way of reporting e.g. validation <p>Using <code>Result</code>-like enums can be a useful way of reporting e.g. validation
errors from a mutation:</p> errors from a mutation:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
# use juniper::{graphql_object, GraphQLObject};
# #[derive(juniper::GraphQLObject)] struct User { name: String } # #[derive(juniper::GraphQLObject)] struct User { name: String }
#
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
struct ValidationError { struct ValidationError {
field: String, field: String,
message: String, message: String,
@ -2621,7 +2647,7 @@ enum SignUpResult {
Error(Vec&lt;ValidationError&gt;), Error(Vec&lt;ValidationError&gt;),
} }
#[juniper::graphql_object] #[graphql_object]
impl SignUpResult { impl SignUpResult {
fn user(&amp;self) -&gt; Option&lt;&amp;User&gt; { fn user(&amp;self) -&gt; Option&lt;&amp;User&gt; {
match *self { match *self {
@ -2637,7 +2663,7 @@ impl SignUpResult {
} }
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>Here, we use an enum to decide whether a user's input data was valid or not, and <p>Here, we use an enum to decide whether a user's input data was valid or not, and
@ -3042,7 +3068,7 @@ sequentially:</p>
# extern crate juniper; # extern crate juniper;
# extern crate juniper_subscriptions; # extern crate juniper_subscriptions;
# extern crate tokio; # extern crate tokio;
# use juniper::FieldError; # use juniper::{graphql_object, graphql_subscription, FieldError};
# use futures::Stream; # use futures::Stream;
# use std::pin::Pin; # use std::pin::Pin;
# #
@ -3051,7 +3077,7 @@ sequentially:</p>
# impl juniper::Context for Database {} # impl juniper::Context for Database {}
# pub struct Query; # pub struct Query;
# #[juniper::graphql_object(Context = Database)] # #[graphql_object(context = Database)]
# impl Query { # impl Query {
# fn hello_world() -&gt; &amp;str { # fn hello_world() -&gt; &amp;str {
# &quot;Hello World!&quot; # &quot;Hello World!&quot;
@ -3061,7 +3087,7 @@ pub struct Subscription;
type StringStream = Pin&lt;Box&lt;dyn Stream&lt;Item = Result&lt;String, FieldError&gt;&gt; + Send&gt;&gt;; type StringStream = Pin&lt;Box&lt;dyn Stream&lt;Item = Result&lt;String, FieldError&gt;&gt; + Send&gt;&gt;;
#[juniper::graphql_subscription(Context = Database)] #[graphql_subscription(context = Database)]
impl Subscription { impl Subscription {
async fn hello_world() -&gt; StringStream { async fn hello_world() -&gt; StringStream {
let stream = tokio::stream::iter(vec![ let stream = tokio::stream::iter(vec![
@ -3071,6 +3097,7 @@ impl Subscription {
Box::pin(stream) Box::pin(stream)
} }
} }
#
# fn main () {} # fn main () {}
</code></pre></pre> </code></pre></pre>
<a class="header" href="#coordinator" id="coordinator"><h3>Coordinator</h3></a> <a class="header" href="#coordinator" id="coordinator"><h3>Coordinator</h3></a>
@ -3088,8 +3115,12 @@ where [<code>Connection</code>][Connection] is a <code>Stream</code> of values r
# extern crate juniper_subscriptions; # extern crate juniper_subscriptions;
# extern crate serde_json; # extern crate serde_json;
# extern crate tokio; # extern crate tokio;
# use juniper::http::GraphQLRequest; # use juniper::{
# use juniper::{DefaultScalarValue, EmptyMutation, FieldError, RootNode, SubscriptionCoordinator}; # http::GraphQLRequest,
# graphql_object, graphql_subscription,
# DefaultScalarValue, EmptyMutation, FieldError,
# RootNode, SubscriptionCoordinator,
# };
# use juniper_subscriptions::Coordinator; # use juniper_subscriptions::Coordinator;
# use futures::{Stream, StreamExt}; # use futures::{Stream, StreamExt};
# use std::pin::Pin; # use std::pin::Pin;
@ -3107,7 +3138,7 @@ where [<code>Connection</code>][Connection] is a <code>Stream</code> of values r
# #
# pub struct Query; # pub struct Query;
# #
# #[juniper::graphql_object(Context = Database)] # #[graphql_object(context = Database)]
# impl Query { # impl Query {
# fn hello_world() -&gt; &amp;str { # fn hello_world() -&gt; &amp;str {
# &quot;Hello World!&quot; # &quot;Hello World!&quot;
@ -3118,7 +3149,7 @@ where [<code>Connection</code>][Connection] is a <code>Stream</code> of values r
# #
# type StringStream = Pin&lt;Box&lt;dyn Stream&lt;Item = Result&lt;String, FieldError&gt;&gt; + Send&gt;&gt;; # type StringStream = Pin&lt;Box&lt;dyn Stream&lt;Item = Result&lt;String, FieldError&gt;&gt; + Send&gt;&gt;;
# #
# #[juniper::graphql_subscription(Context = Database)] # #[graphql_subscription(context = Database)]
# impl Subscription { # impl Subscription {
# async fn hello_world() -&gt; StringStream { # async fn hello_world() -&gt; StringStream {
# let stream = # let stream =
@ -3136,11 +3167,9 @@ async fn run_subscription() {
let schema = schema(); let schema = schema();
let coordinator = Coordinator::new(schema); let coordinator = Coordinator::new(schema);
let req: GraphQLRequest&lt;DefaultScalarValue&gt; = serde_json::from_str( let req: GraphQLRequest&lt;DefaultScalarValue&gt; = serde_json::from_str(
r#&quot; r#&quot;{
{
&quot;query&quot;: &quot;subscription { helloWorld }&quot; &quot;query&quot;: &quot;subscription { helloWorld }&quot;
} }&quot;#,
&quot;#,
) )
.unwrap(); .unwrap();
let ctx = Database::new(); let ctx = Database::new();
@ -3149,7 +3178,7 @@ async fn run_subscription() {
println!(&quot;{}&quot;, serde_json::to_string(&amp;result).unwrap()); println!(&quot;{}&quot;, serde_json::to_string(&amp;result).unwrap());
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<a class="header" href="#web-integration-and-examples" id="web-integration-and-examples"><h3>Web Integration and Examples</h3></a> <a class="header" href="#web-integration-and-examples" id="web-integration-and-examples"><h3>Web Integration and Examples</h3></a>

52
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@ -155,8 +155,12 @@ types to a GraphQL schema. The most important one is the
resolvers, which you will use for the <code>Query</code> and <code>Mutation</code> roots.</p> resolvers, which you will use for the <code>Query</code> and <code>Mutation</code> roots.</p>
<pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)] <pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)]
# extern crate juniper; # extern crate juniper;
use juniper::{FieldResult, EmptySubscription}; # use std::fmt::Display;
use juniper::{
graphql_object, EmptySubscription, FieldResult, GraphQLEnum,
GraphQLInputObject, GraphQLObject, ScalarValue,
};
#
# struct DatabasePool; # struct DatabasePool;
# impl DatabasePool { # impl DatabasePool {
# fn get_connection(&amp;self) -&gt; FieldResult&lt;DatabasePool&gt; { Ok(DatabasePool) } # fn get_connection(&amp;self) -&gt; FieldResult&lt;DatabasePool&gt; { Ok(DatabasePool) }
@ -164,14 +168,14 @@ use juniper::{FieldResult, EmptySubscription};
# fn insert_human(&amp;self, _human: &amp;NewHuman) -&gt; FieldResult&lt;Human&gt; { Err(&quot;&quot;)? } # fn insert_human(&amp;self, _human: &amp;NewHuman) -&gt; FieldResult&lt;Human&gt; { Err(&quot;&quot;)? }
# } # }
#[derive(juniper::GraphQLEnum)] #[derive(GraphQLEnum)]
enum Episode { enum Episode {
NewHope, NewHope,
Empire, Empire,
Jedi, Jedi,
} }
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
#[graphql(description = &quot;A humanoid creature in the Star Wars universe&quot;)] #[graphql(description = &quot;A humanoid creature in the Star Wars universe&quot;)]
struct Human { struct Human {
id: String, id: String,
@ -182,7 +186,7 @@ struct Human {
// There is also a custom derive for mapping GraphQL input objects. // There is also a custom derive for mapping GraphQL input objects.
#[derive(juniper::GraphQLInputObject)] #[derive(GraphQLInputObject)]
#[graphql(description = &quot;A humanoid creature in the Star Wars universe&quot;)] #[graphql(description = &quot;A humanoid creature in the Star Wars universe&quot;)]
struct NewHuman { struct NewHuman {
name: String, name: String,
@ -205,14 +209,13 @@ impl juniper::Context for Context {}
struct Query; struct Query;
#[juniper::graphql_object( #[graphql_object(
// Here we specify the context type for the object. // Here we specify the context type for the object.
// We need to do this in every type that // We need to do this in every type that
// needs access to the context. // needs access to the context.
Context = Context, context = Context,
)] )]
impl Query { impl Query {
fn apiVersion() -&gt; &amp;str { fn apiVersion() -&gt; &amp;str {
&quot;1.0&quot; &quot;1.0&quot;
} }
@ -236,14 +239,18 @@ impl Query {
struct Mutation; struct Mutation;
#[juniper::graphql_object( #[graphql_object(
Context = Context, context = Context,
)]
impl Mutation {
fn createHuman(context: &amp;Context, new_human: NewHuman) -&gt; FieldResult&lt;Human&gt; { // If we need to use `ScalarValue` parametrization explicitly somewhere
let db = context.pool.get_connection()?; // in the object definition (like here in `FieldResult`), we should
let human: Human = db.insert_human(&amp;new_human)?; // declare an explicit type parameter for that, and specify it.
scalar = S,
)]
impl&lt;S: ScalarValue + Display&gt; Mutation {
fn createHuman(context: &amp;Context, new_human: NewHuman) -&gt; FieldResult&lt;Human, S&gt; {
let db = context.pool.get_connection().map_err(|e| e.map_scalar_value())?;
let human: Human = db.insert_human(&amp;new_human).map_err(|e| e.map_scalar_value())?;
Ok(human) Ok(human)
} }
} }
@ -251,7 +258,7 @@ impl Mutation {
// A root schema consists of a query, a mutation, and a subscription. // A root schema consists of a query, a mutation, and a subscription.
// Request queries can be executed against a RootNode. // Request queries can be executed against a RootNode.
type Schema = juniper::RootNode&lt;'static, Query, Mutation, EmptySubscription&lt;Context&gt;&gt;; type Schema = juniper::RootNode&lt;'static, Query, Mutation, EmptySubscription&lt;Context&gt;&gt;;
#
# fn main() { # fn main() {
# let _ = Schema::new(Query, Mutation{}, EmptySubscription::new()); # let _ = Schema::new(Query, Mutation{}, EmptySubscription::new());
# } # }
@ -263,10 +270,12 @@ type Schema = juniper::RootNode&lt;'static, Query, Mutation, EmptySubscription&l
<p>You can invoke <code>juniper::execute</code> directly to run a GraphQL query:</p> <p>You can invoke <code>juniper::execute</code> directly to run a GraphQL query:</p>
<pre><pre class="playpen"><code class="language-rust"># // Only needed due to 2018 edition because the macro is not accessible. <pre><pre class="playpen"><code class="language-rust"># // Only needed due to 2018 edition because the macro is not accessible.
# #[macro_use] extern crate juniper; # #[macro_use] extern crate juniper;
use juniper::{FieldResult, Variables, EmptyMutation, EmptySubscription}; use juniper::{
graphql_object, EmptyMutation, EmptySubscription, FieldResult,
GraphQLEnum, Variables,
};
#[derive(GraphQLEnum, Clone, Copy)]
#[derive(juniper::GraphQLEnum, Clone, Copy)]
enum Episode { enum Episode {
NewHope, NewHope,
Empire, Empire,
@ -280,16 +289,13 @@ impl juniper::Context for Ctx {}
struct Query; struct Query;
#[juniper::graphql_object( #[graphql_object(context = Ctx)]
Context = Ctx,
)]
impl Query { impl Query {
fn favoriteEpisode(context: &amp;Ctx) -&gt; FieldResult&lt;Episode&gt; { fn favoriteEpisode(context: &amp;Ctx) -&gt; FieldResult&lt;Episode&gt; {
Ok(context.0) Ok(context.0)
} }
} }
// A root schema consists of a query, a mutation, and a subscription. // A root schema consists of a query, a mutation, and a subscription.
// Request queries can be executed against a RootNode. // Request queries can be executed against a RootNode.
type Schema = juniper::RootNode&lt;'static, Query, EmptyMutation&lt;Ctx&gt;, EmptySubscription&lt;Ctx&gt;&gt;; type Schema = juniper::RootNode&lt;'static, Query, EmptyMutation&lt;Ctx&gt;, EmptySubscription&lt;Ctx&gt;&gt;;

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@ -153,18 +153,18 @@ object somewhere but never reference it, it will not be exposed in a schema.</p>
object in Juniper, most commonly using the <code>graphql_object</code> proc macro:</p> object in Juniper, most commonly using the <code>graphql_object</code> proc macro:</p>
<pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)] <pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)]
# extern crate juniper; # extern crate juniper;
# use juniper::FieldResult; # use juniper::{graphql_object, FieldResult, GraphQLObject};
# #[derive(juniper::GraphQLObject)] struct User { name: String } # #[derive(GraphQLObject)] struct User { name: String }
struct Root; struct Root;
#[juniper::graphql_object] #[graphql_object]
impl Root { impl Root {
fn userWithUsername(username: String) -&gt; FieldResult&lt;Option&lt;User&gt;&gt; { fn userWithUsername(username: String) -&gt; FieldResult&lt;Option&lt;User&gt;&gt; {
// Look up user in database... // Look up user in database...
# unimplemented!() # unimplemented!()
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<a class="header" href="#mutations" id="mutations"><h2>Mutations</h2></a> <a class="header" href="#mutations" id="mutations"><h2>Mutations</h2></a>
@ -172,28 +172,30 @@ impl Root {
that performs some mutating side-effect such as updating a database.</p> that performs some mutating side-effect such as updating a database.</p>
<pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)] <pre><pre class="playpen"><code class="language-rust"># #![allow(unused_variables)]
# extern crate juniper; # extern crate juniper;
# use juniper::FieldResult; # use juniper::{graphql_object, FieldResult, GraphQLObject};
# #[derive(juniper::GraphQLObject)] struct User { name: String } # #[derive(GraphQLObject)] struct User { name: String }
struct Mutations; struct Mutations;
#[juniper::graphql_object] #[graphql_object]
impl Mutations { impl Mutations {
fn signUpUser(name: String, email: String) -&gt; FieldResult&lt;User&gt; { fn signUpUser(name: String, email: String) -&gt; FieldResult&lt;User&gt; {
// Validate inputs and save user in database... // Validate inputs and save user in database...
# unimplemented!() # unimplemented!()
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<a class="header" href="#converting-a-rust-schema-to-the-a-hrefhttpsgraphqlorglearnschematype-languagegraphql-schema-languagea" id="converting-a-rust-schema-to-the-a-hrefhttpsgraphqlorglearnschematype-languagegraphql-schema-languagea"><h1>Converting a Rust schema to the <a href="https://graphql.org/learn/schema/#type-language">GraphQL Schema Language</a></h1></a> <a class="header" href="#converting-a-rust-schema-to-the-a-hrefhttpsgraphqlorglearnschematype-languagegraphql-schema-languagea" id="converting-a-rust-schema-to-the-a-hrefhttpsgraphqlorglearnschematype-languagegraphql-schema-languagea"><h1>Converting a Rust schema to the <a href="https://graphql.org/learn/schema/#type-language">GraphQL Schema Language</a></h1></a>
<p>Many tools in the GraphQL ecosystem require the schema to be defined in the <a href="https://graphql.org/learn/schema/#type-language">GraphQL Schema Language</a>. You can generate a <a href="https://graphql.org/learn/schema/#type-language">GraphQL Schema Language</a> representation of your schema defined in Rust using the <code>schema-language</code> feature (on by default):</p> <p>Many tools in the GraphQL ecosystem require the schema to be defined in the <a href="https://graphql.org/learn/schema/#type-language">GraphQL Schema Language</a>. You can generate a <a href="https://graphql.org/learn/schema/#type-language">GraphQL Schema Language</a> representation of your schema defined in Rust using the <code>schema-language</code> feature (on by default):</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
use juniper::{FieldResult, EmptyMutation, EmptySubscription, RootNode}; use juniper::{
graphql_object, EmptyMutation, EmptySubscription, FieldResult, RootNode,
};
struct Query; struct Query;
#[juniper::graphql_object] #[graphql_object]
impl Query { impl Query {
fn hello(&amp;self) -&gt; FieldResult&lt;&amp;str&gt; { fn hello(&amp;self) -&gt; FieldResult&lt;&amp;str&gt; {
Ok(&quot;hello world&quot;) Ok(&quot;hello world&quot;)

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@ -139,7 +139,7 @@
<a class="header" href="#complex-fields" id="complex-fields"><h1>Complex fields</h1></a> <a class="header" href="#complex-fields" id="complex-fields"><h1>Complex fields</h1></a>
<p>If you've got a struct that can't be mapped directly to GraphQL, that contains <p>If you've got a struct that can't be mapped directly to GraphQL, that contains
computed fields or circular structures, you have to use a more powerful tool: computed fields or circular structures, you have to use a more powerful tool:
the <code>object</code> procedural macro. This macro lets you define GraphQL object the <code>#[graphql_object]</code> procedural macro. This macro lets you define GraphQL object
fields in a Rust <code>impl</code> block for a type. Note that only GraphQL fields fields in a Rust <code>impl</code> block for a type. Note that only GraphQL fields
can be specified in this <code>impl</code> block. If you want to define normal methods on the struct, can be specified in this <code>impl</code> block. If you want to define normal methods on the struct,
you have to do so in a separate, normal <code>impl</code> block. Continuing with the you have to do so in a separate, normal <code>impl</code> block. Continuing with the
@ -147,13 +147,14 @@ example from the last chapter, this is how you would define <code>Person</code>
macro:</p> macro:</p>
<pre><pre class="playpen"><code class="language-rust"># #![allow(dead_code)] <pre><pre class="playpen"><code class="language-rust"># #![allow(dead_code)]
# extern crate juniper; # extern crate juniper;
# use juniper::graphql_object;
# #
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
} }
#[juniper::graphql_object] #[graphql_object]
impl Person { impl Person {
fn name(&amp;self) -&gt; &amp;str { fn name(&amp;self) -&gt; &amp;str {
self.name.as_str() self.name.as_str()
@ -171,13 +172,15 @@ impl Person {
// [...] // [...]
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<p>While this is a bit more verbose, it lets you write any kind of function in the <p>While this is a bit more verbose, it lets you write any kind of function in the
field resolver. With this syntax, fields can also take arguments:</p> field resolver. With this syntax, fields can also take arguments:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::{graphql_object, GraphQLObject};
#
#[derive(GraphQLObject)]
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
@ -187,14 +190,14 @@ struct House {
inhabitants: Vec&lt;Person&gt;, inhabitants: Vec&lt;Person&gt;,
} }
#[juniper::graphql_object] #[graphql_object]
impl House { impl House {
// Creates the field inhabitantWithName(name), returning a nullable person // Creates the field inhabitantWithName(name), returning a nullable person
fn inhabitant_with_name(&amp;self, name: String) -&gt; Option&lt;&amp;Person&gt; { fn inhabitant_with_name(&amp;self, name: String) -&gt; Option&lt;&amp;Person&gt; {
self.inhabitants.iter().find(|p| p.name == name) self.inhabitants.iter().find(|p| p.name == name)
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>To access global data such as database connections or authentication <p>To access global data such as database connections or authentication
@ -205,20 +208,20 @@ chapter: <a href="using_contexts.html">Using contexts</a>.</p>
to <code>camelCase</code>. If you need to override the conversion, you can simply rename to <code>camelCase</code>. If you need to override the conversion, you can simply rename
the field. Also, the type name can be changed with an alias:</p> the field. Also, the type name can be changed with an alias:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
# use juniper::graphql_object;
struct Person { #
} struct Person;
/// Doc comments are used as descriptions for GraphQL. /// Doc comments are used as descriptions for GraphQL.
#[juniper::graphql_object( #[graphql_object(
// With this attribute you can change the public GraphQL name of the type. // With this attribute you can change the public GraphQL name of the type.
name = &quot;PersonObject&quot;, name = &quot;PersonObject&quot;,
// You can also specify a description here, which will overwrite // You can also specify a description here, which will overwrite
// a doc comment description. // a doc comment description.
description = &quot;...&quot;, description = &quot;...&quot;,
)] )]
impl Person { impl Person {
/// A doc comment on the field will also be used for GraphQL. /// A doc comment on the field will also be used for GraphQL.
#[graphql( #[graphql(
// Or provide a description here. // Or provide a description here.
@ -229,9 +232,7 @@ impl Person {
} }
// Fields can also be renamed if required. // Fields can also be renamed if required.
#[graphql( #[graphql(name = &quot;myCustomFieldName&quot;)]
name = &quot;myCustomFieldName&quot;,
)]
fn renamed_field() -&gt; bool { fn renamed_field() -&gt; bool {
true true
} }
@ -248,7 +249,7 @@ impl Person {
true true
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<a class="header" href="#customizing-arguments" id="customizing-arguments"><h2>Customizing arguments</h2></a> <a class="header" href="#customizing-arguments" id="customizing-arguments"><h2>Customizing arguments</h2></a>
@ -257,10 +258,11 @@ impl Person {
<p><strong>Note</strong>: The syntax for this is currently a little awkward. <p><strong>Note</strong>: The syntax for this is currently a little awkward.
This will become better once the <a href="https://github.com/rust-lang/rust/issues/60406">Rust RFC 2565</a> is implemented.</p> This will become better once the <a href="https://github.com/rust-lang/rust/issues/60406">Rust RFC 2565</a> is implemented.</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
# use juniper::graphql_object;
#
struct Person {} struct Person {}
#[juniper::graphql_object] #[graphql_object]
impl Person { impl Person {
#[graphql( #[graphql(
arguments( arguments(
@ -280,7 +282,7 @@ impl Person {
format!(&quot;{} {}&quot;, arg1, arg2) format!(&quot;{} {}&quot;, arg1, arg2)
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<a class="header" href="#more-features" id="more-features"><h2>More features</h2></a> <a class="header" href="#more-features" id="more-features"><h2>More features</h2></a>
@ -290,7 +292,7 @@ impl Person {
<li>Per-argument default values</li> <li>Per-argument default values</li>
<li>Per-argument descriptions</li> <li>Per-argument descriptions</li>
</ul> </ul>
<p>These, and more features, are described more thorougly in <a href="https://docs.rs/juniper/latest/juniper/macro.object.html">the reference <p>These, and more features, are described more thoroughly in <a href="https://docs.rs/juniper/latest/juniper/macro.object.html">the reference
documentation</a>.</p> documentation</a>.</p>
</main> </main>

47
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@ -144,12 +144,13 @@ struct you want to expose, the easiest way is to use the custom derive
attribute. The other way is described in the <a href="complex_fields.html">Complex fields</a> attribute. The other way is described in the <a href="complex_fields.html">Complex fields</a>
chapter.</p> chapter.</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>This will create a GraphQL object type called <code>Person</code>, with two fields: <code>name</code> <p>This will create a GraphQL object type called <code>Person</code>, with two fields: <code>name</code>
@ -162,7 +163,8 @@ fields. Juniper will automatically use associated doc comments as GraphQL
descriptions:</p> descriptions:</p>
<p>!FILENAME GraphQL descriptions via Rust doc comments</p> <p>!FILENAME GraphQL descriptions via Rust doc comments</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
/// Information about a person /// Information about a person
struct Person { struct Person {
/// The person's full name, including both first and last names /// The person's full name, including both first and last names
@ -170,14 +172,15 @@ struct Person {
/// The person's age in years, rounded down /// The person's age in years, rounded down
age: i32, age: i32,
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>Objects and fields without doc comments can instead set a <code>description</code> <p>Objects and fields without doc comments can instead set a <code>description</code>
via the <code>graphql</code> attribute. The following example is equivalent to the above:</p> via the <code>graphql</code> attribute. The following example is equivalent to the above:</p>
<p>!FILENAME GraphQL descriptions via attribute</p> <p>!FILENAME GraphQL descriptions via attribute</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
#[graphql(description = &quot;Information about a person&quot;)] #[graphql(description = &quot;Information about a person&quot;)]
struct Person { struct Person {
#[graphql(description = &quot;The person's full name, including both first and last names&quot;)] #[graphql(description = &quot;The person's full name, including both first and last names&quot;)]
@ -185,14 +188,15 @@ struct Person {
#[graphql(description = &quot;The person's age in years, rounded down&quot;)] #[graphql(description = &quot;The person's age in years, rounded down&quot;)]
age: i32, age: i32,
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>Descriptions set via the <code>graphql</code> attribute take precedence over Rust <p>Descriptions set via the <code>graphql</code> attribute take precedence over Rust
doc comments. This enables internal Rust documentation and external GraphQL doc comments. This enables internal Rust documentation and external GraphQL
documentation to differ:</p> documentation to differ:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
#[graphql(description = &quot;This description shows up in GraphQL&quot;)] #[graphql(description = &quot;This description shows up in GraphQL&quot;)]
/// This description shows up in RustDoc /// This description shows up in RustDoc
struct Person { struct Person {
@ -202,7 +206,7 @@ struct Person {
/// This description shows up in both RustDoc and GraphQL /// This description shows up in both RustDoc and GraphQL
age: i32, age: i32,
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<a class="header" href="#relationships" id="relationships"><h2>Relationships</h2></a> <a class="header" href="#relationships" id="relationships"><h2>Relationships</h2></a>
@ -221,18 +225,19 @@ or</li>
</ul> </ul>
<p>Let's see what that means for building relationships between objects:</p> <p>Let's see what that means for building relationships between objects:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
} }
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
struct House { struct House {
address: Option&lt;String&gt;, // Converted into String (nullable) address: Option&lt;String&gt;, // Converted into String (nullable)
inhabitants: Vec&lt;Person&gt;, // Converted into [Person!]! inhabitants: Vec&lt;Person&gt;, // Converted into [Person!]!
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>Because <code>Person</code> is a valid GraphQL type, you can have a <code>Vec&lt;Person&gt;</code> in a <p>Because <code>Person</code> is a valid GraphQL type, you can have a <code>Vec&lt;Person&gt;</code> in a
@ -242,39 +247,42 @@ objects.</p>
<p>By default, struct fields are converted from Rust's standard <code>snake_case</code> naming <p>By default, struct fields are converted from Rust's standard <code>snake_case</code> naming
convention into GraphQL's <code>camelCase</code> convention:</p> convention into GraphQL's <code>camelCase</code> convention:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
struct Person { struct Person {
first_name: String, // Would be exposed as firstName in the GraphQL schema first_name: String, // Would be exposed as firstName in the GraphQL schema
last_name: String, // Exposed as lastName last_name: String, // Exposed as lastName
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>You can override the name by using the <code>graphql</code> attribute on individual struct <p>You can override the name by using the <code>graphql</code> attribute on individual struct
fields:</p> fields:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
#[graphql(name = &quot;websiteURL&quot;)] #[graphql(name = &quot;websiteURL&quot;)]
website_url: Option&lt;String&gt;, // Now exposed as websiteURL in the schema website_url: Option&lt;String&gt;, // Now exposed as websiteURL in the schema
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<a class="header" href="#deprecating-fields" id="deprecating-fields"><h2>Deprecating fields</h2></a> <a class="header" href="#deprecating-fields" id="deprecating-fields"><h2>Deprecating fields</h2></a>
<p>To deprecate a field, you specify a deprecation reason using the <code>graphql</code> <p>To deprecate a field, you specify a deprecation reason using the <code>graphql</code>
attribute:</p> attribute:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
#[graphql(deprecated = &quot;Please use the name field instead&quot;)] #[graphql(deprecated = &quot;Please use the name field instead&quot;)]
first_name: String, first_name: String,
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>The <code>name</code>, <code>description</code>, and <code>deprecation</code> arguments can of course be <p>The <code>name</code>, <code>description</code>, and <code>deprecation</code> arguments can of course be
@ -283,7 +291,8 @@ only deprecate object fields and enum values.</p>
<a class="header" href="#skipping-fields" id="skipping-fields"><h2>Skipping fields</h2></a> <a class="header" href="#skipping-fields" id="skipping-fields"><h2>Skipping fields</h2></a>
<p>By default all fields in a <code>GraphQLObject</code> are included in the generated GraphQL type. To prevent including a specific field, annotate the field with <code>#[graphql(skip)]</code>:</p> <p>By default all fields in a <code>GraphQLObject</code> are included in the generated GraphQL type. To prevent including a specific field, annotate the field with <code>#[graphql(skip)]</code>:</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::GraphQLObject;
#[derive(GraphQLObject)]
struct Person { struct Person {
name: String, name: String,
age: i32, age: i32,
@ -291,7 +300,7 @@ struct Person {
# #[allow(dead_code)] # #[allow(dead_code)]
password_hash: String, // This cannot be queried or modified from GraphQL password_hash: String, // This cannot be queried or modified from GraphQL
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>

73
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@ -160,13 +160,13 @@ use std::{
fs::{File}, fs::{File},
io::{Read}, io::{Read},
}; };
use juniper::FieldResult; use juniper::{graphql_object, FieldResult};
struct Example { struct Example {
filename: PathBuf, filename: PathBuf,
} }
#[juniper::graphql_object] #[graphql_object]
impl Example { impl Example {
fn contents() -&gt; FieldResult&lt;String&gt; { fn contents() -&gt; FieldResult&lt;String&gt; {
let mut file = File::open(&amp;self.filename)?; let mut file = File::open(&amp;self.filename)?;
@ -185,7 +185,7 @@ impl Example {
} }
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p><code>FieldResult&lt;T&gt;</code> is an alias for <code>Result&lt;T, FieldError&gt;</code>, which is the error <p><code>FieldResult&lt;T&gt;</code> is an alias for <code>Result&lt;T, FieldError&gt;</code>, which is the error
@ -245,14 +245,16 @@ following would be returned:</p>
<p>Sometimes it is desirable to return additional structured error information <p>Sometimes it is desirable to return additional structured error information
to clients. This can be accomplished by implementing <a href="https://docs.rs/juniper/latest/juniper/trait.IntoFieldError.html"><code>IntoFieldError</code></a>:</p> to clients. This can be accomplished by implementing <a href="https://docs.rs/juniper/latest/juniper/trait.IntoFieldError.html"><code>IntoFieldError</code></a>:</p>
<pre><pre class="playpen"><code class="language-rust"># #[macro_use] extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># #[macro_use] extern crate juniper;
# use juniper::{graphql_object, FieldError, IntoFieldError, ScalarValue};
#
enum CustomError { enum CustomError {
WhateverNotSet, WhateverNotSet,
} }
impl juniper::IntoFieldError for CustomError { impl&lt;S: ScalarValue&gt; IntoFieldError&lt;S&gt; for CustomError {
fn into_field_error(self) -&gt; juniper::FieldError { fn into_field_error(self) -&gt; FieldError&lt;S&gt; {
match self { match self {
CustomError::WhateverNotSet =&gt; juniper::FieldError::new( CustomError::WhateverNotSet =&gt; FieldError::new(
&quot;Whatever does not exist&quot;, &quot;Whatever does not exist&quot;,
graphql_value!({ graphql_value!({
&quot;type&quot;: &quot;NO_WHATEVER&quot; &quot;type&quot;: &quot;NO_WHATEVER&quot;
@ -266,7 +268,7 @@ struct Example {
whatever: Option&lt;bool&gt;, whatever: Option&lt;bool&gt;,
} }
#[juniper::graphql_object] #[graphql_object]
impl Example { impl Example {
fn whatever() -&gt; Result&lt;bool, CustomError&gt; { fn whatever() -&gt; Result&lt;bool, CustomError&gt; {
if let Some(value) = self.whatever { if let Some(value) = self.whatever {
@ -275,18 +277,18 @@ impl Example {
Err(CustomError::WhateverNotSet) Err(CustomError::WhateverNotSet)
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>The specified structured error information is included in the <a href="https://facebook.github.io/graphql/June2018/#sec-Errors"><code>extensions</code></a> key:</p> <p>The specified structured error information is included in the <a href="https://facebook.github.io/graphql/June2018/#sec-Errors"><code>extensions</code></a> key:</p>
<pre><code class="language-js">{ <pre><code class="language-json">{
&quot;errors&quot;: [ &quot;errors&quot;: [{
&quot;message&quot;: &quot;Whatever does not exist&quot;, &quot;message&quot;: &quot;Whatever does not exist&quot;,
&quot;locations&quot;: [{ &quot;line&quot;: 2, &quot;column&quot;: 4 }]), &quot;locations&quot;: [{&quot;line&quot;: 2, &quot;column&quot;: 4}],
&quot;extensions&quot;: { &quot;extensions&quot;: {
&quot;type&quot;: &quot;NO_WHATEVER&quot; &quot;type&quot;: &quot;NO_WHATEVER&quot;
} }
] }]
} }
</code></pre> </code></pre>
<a class="header" href="#errors-backed-by-graphqls-schema" id="errors-backed-by-graphqls-schema"><h2>Errors Backed by GraphQL's Schema</h2></a> <a class="header" href="#errors-backed-by-graphqls-schema" id="errors-backed-by-graphqls-schema"><h2>Errors Backed by GraphQL's Schema</h2></a>
@ -308,24 +310,26 @@ for a particular field are also returned as a string. In this example
the string contains a server-side localized error message. However, it is also the string contains a server-side localized error message. However, it is also
possible to return a unique string identifier and have the client present a localized string to the user.</p> possible to return a unique string identifier and have the client present a localized string to the user.</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::{graphql_object, GraphQLObject, GraphQLUnion};
#
#[derive(GraphQLObject)]
pub struct Item { pub struct Item {
name: String, name: String,
quantity: i32, quantity: i32,
} }
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
pub struct ValidationError { pub struct ValidationError {
field: String, field: String,
message: String, message: String,
} }
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
pub struct ValidationErrors { pub struct ValidationErrors {
errors: Vec&lt;ValidationError&gt;, errors: Vec&lt;ValidationError&gt;,
} }
#[derive(juniper::GraphQLUnion)] #[derive(GraphQLUnion)]
pub enum GraphQLResult { pub enum GraphQLResult {
Ok(Item), Ok(Item),
Err(ValidationErrors), Err(ValidationErrors),
@ -333,7 +337,7 @@ pub enum GraphQLResult {
pub struct Mutation; pub struct Mutation;
#[juniper::graphql_object] #[graphql_object]
impl Mutation { impl Mutation {
fn addItem(&amp;self, name: String, quantity: i32) -&gt; GraphQLResult { fn addItem(&amp;self, name: String, quantity: i32) -&gt; GraphQLResult {
let mut errors = Vec::new(); let mut errors = Vec::new();
@ -359,7 +363,7 @@ impl Mutation {
} }
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<p>Each function may have a different return type and depending on the input <p>Each function may have a different return type and depending on the input
@ -395,19 +399,21 @@ field is set if the validation for that particular field fails. You will likely
before. Each resolver function has a custom <code>ValidationResult</code> which before. Each resolver function has a custom <code>ValidationResult</code> which
contains only fields provided by the function.</p> contains only fields provided by the function.</p>
<pre><pre class="playpen"><code class="language-rust"># extern crate juniper; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
#[derive(juniper::GraphQLObject)] # use juniper::{graphql_object, GraphQLObject, GraphQLUnion};
#
#[derive(GraphQLObject)]
pub struct Item { pub struct Item {
name: String, name: String,
quantity: i32, quantity: i32,
} }
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
pub struct ValidationError { pub struct ValidationError {
name: Option&lt;String&gt;, name: Option&lt;String&gt;,
quantity: Option&lt;String&gt;, quantity: Option&lt;String&gt;,
} }
#[derive(juniper::GraphQLUnion)] #[derive(GraphQLUnion)]
pub enum GraphQLResult { pub enum GraphQLResult {
Ok(Item), Ok(Item),
Err(ValidationError), Err(ValidationError),
@ -415,7 +421,7 @@ pub enum GraphQLResult {
pub struct Mutation; pub struct Mutation;
#[juniper::graphql_object] #[graphql_object]
impl Mutation { impl Mutation {
fn addItem(&amp;self, name: String, quantity: i32) -&gt; GraphQLResult { fn addItem(&amp;self, name: String, quantity: i32) -&gt; GraphQLResult {
let mut error = ValidationError { let mut error = ValidationError {
@ -438,7 +444,7 @@ impl Mutation {
} }
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<pre><code class="language-graphql">{ <pre><code class="language-graphql">{
@ -464,22 +470,23 @@ errors when they occur.</p>
<p>In the following example, a theoretical database could fail <p>In the following example, a theoretical database could fail
and would generate errors. Since it is not common for the database to and would generate errors. Since it is not common for the database to
fail, the corresponding error is returned as a critical error:</p> fail, the corresponding error is returned as a critical error:</p>
<pre><pre class="playpen"><code class="language-rust"># // Only needed due to 2018 edition because the macro is not accessible. <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
# #[macro_use] extern crate juniper; #
use juniper::{graphql_object, graphql_value, FieldError, GraphQLObject, GraphQLUnion, ScalarValue};
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
pub struct Item { pub struct Item {
name: String, name: String,
quantity: i32, quantity: i32,
} }
#[derive(juniper::GraphQLObject)] #[derive(GraphQLObject)]
pub struct ValidationErrorItem { pub struct ValidationErrorItem {
name: Option&lt;String&gt;, name: Option&lt;String&gt;,
quantity: Option&lt;String&gt;, quantity: Option&lt;String&gt;,
} }
#[derive(juniper::GraphQLUnion)] #[derive(GraphQLUnion)]
pub enum GraphQLResult { pub enum GraphQLResult {
Ok(Item), Ok(Item),
Err(ValidationErrorItem), Err(ValidationErrorItem),
@ -489,10 +496,10 @@ pub enum ApiError {
Database, Database,
} }
impl juniper::IntoFieldError for ApiError { impl&lt;S: ScalarValue&gt; juniper::IntoFieldError&lt;S&gt; for ApiError {
fn into_field_error(self) -&gt; juniper::FieldError { fn into_field_error(self) -&gt; FieldError&lt;S&gt; {
match self { match self {
ApiError::Database =&gt; juniper::FieldError::new( ApiError::Database =&gt; FieldError::new(
&quot;Internal database error&quot;, &quot;Internal database error&quot;,
graphql_value!({ graphql_value!({
&quot;type&quot;: &quot;DATABASE&quot; &quot;type&quot;: &quot;DATABASE&quot;
@ -504,7 +511,7 @@ impl juniper::IntoFieldError for ApiError {
pub struct Mutation; pub struct Mutation;
#[juniper::graphql_object] #[graphql_object]
impl Mutation { impl Mutation {
fn addItem(&amp;self, name: String, quantity: i32) -&gt; Result&lt;GraphQLResult, ApiError&gt; { fn addItem(&amp;self, name: String, quantity: i32) -&gt; Result&lt;GraphQLResult, ApiError&gt; {
let mut error = ValidationErrorItem { let mut error = ValidationErrorItem {
@ -527,7 +534,7 @@ impl Mutation {
} }
} }
} }
#
# fn main() {} # fn main() {}
</code></pre></pre> </code></pre></pre>
<a class="header" href="#additional-material" id="additional-material"><h2>Additional Material</h2></a> <a class="header" href="#additional-material" id="additional-material"><h2>Additional Material</h2></a>

18
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@ -147,7 +147,7 @@ integration.</p>
resolvers. Let's say that we have a simple user database in a <code>HashMap</code>:</p> resolvers. Let's say that we have a simple user database in a <code>HashMap</code>:</p>
<pre><pre class="playpen"><code class="language-rust"># #![allow(dead_code)] <pre><pre class="playpen"><code class="language-rust"># #![allow(dead_code)]
# use std::collections::HashMap; # use std::collections::HashMap;
#
struct Database { struct Database {
users: HashMap&lt;i32, User&gt;, users: HashMap&lt;i32, User&gt;,
} }
@ -157,7 +157,7 @@ struct User {
name: String, name: String,
friend_ids: Vec&lt;i32&gt;, friend_ids: Vec&lt;i32&gt;,
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<p>We would like a <code>friends</code> field on <code>User</code> that returns a list of <code>User</code> objects. <p>We would like a <code>friends</code> field on <code>User</code> that returns a list of <code>User</code> objects.
@ -166,9 +166,10 @@ In order to write such a field though, the database must be queried.</p>
the user object.</p> the user object.</p>
<p>To gain access to the context, we need to specify an argument with the same <p>To gain access to the context, we need to specify an argument with the same
type as the specified <code>Context</code> for the type:</p> type as the specified <code>Context</code> for the type:</p>
<pre><pre class="playpen"><code class="language-rust"># use std::collections::HashMap; <pre><pre class="playpen"><code class="language-rust"># extern crate juniper;
extern crate juniper; # use std::collections::HashMap;
# use juniper::graphql_object;
#
// This struct represents our context. // This struct represents our context.
struct Database { struct Database {
users: HashMap&lt;i32, User&gt;, users: HashMap&lt;i32, User&gt;,
@ -183,11 +184,8 @@ struct User {
friend_ids: Vec&lt;i32&gt;, friend_ids: Vec&lt;i32&gt;,
} }
// Assign Database as the context type for User // Assign Database as the context type for User
#[juniper::graphql_object( #[graphql_object(context = Database)]
Context = Database,
)]
impl User { impl User {
// 3. Inject the context by specifying an argument // 3. Inject the context by specifying an argument
// with the context type. // with the context type.
@ -210,7 +208,7 @@ impl User {
self.id self.id
} }
} }
#
# fn main() { } # fn main() { }
</code></pre></pre> </code></pre></pre>
<p>You only get an immutable reference to the context, so if you want to affect <p>You only get an immutable reference to the context, so if you want to affect