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<ol class="chapter"><li class="chapter-item expanded "><a href="../introduction.html"><strong aria-hidden="true">1.</strong> Introduction</a></li><li class="chapter-item expanded "><a href="../quickstart.html"><strong aria-hidden="true">2.</strong> Quickstart</a></li><li class="chapter-item expanded "><a href="../types/index.html"><strong aria-hidden="true">3.</strong> Type system</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../types/objects/index.html"><strong aria-hidden="true">3.1.</strong> Objects</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../types/objects/complex_fields.html"><strong aria-hidden="true">3.1.1.</strong> Complex fields</a></li><li class="chapter-item expanded "><a href="../types/objects/context.html"><strong aria-hidden="true">3.1.2.</strong> Context</a></li><li class="chapter-item expanded "><a href="../types/objects/error/index.html"><strong aria-hidden="true">3.1.3.</strong> Error handling</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../types/objects/error/field.html"><strong aria-hidden="true">3.1.3.1.</strong> Field errors</a></li><li class="chapter-item expanded "><a href="../types/objects/error/schema.html"><strong aria-hidden="true">3.1.3.2.</strong> Schema errors</a></li></ol></li><li class="chapter-item expanded "><a href="../types/objects/generics.html"><strong aria-hidden="true">3.1.4.</strong> Generics</a></li></ol></li><li class="chapter-item expanded "><a href="../types/interfaces.html" class="active"><strong aria-hidden="true">3.2.</strong> Interfaces</a></li><li class="chapter-item expanded "><a href="../types/unions.html"><strong aria-hidden="true">3.3.</strong> Unions</a></li><li class="chapter-item expanded "><a href="../types/enums.html"><strong aria-hidden="true">3.4.</strong> Enums</a></li><li class="chapter-item expanded "><a href="../types/input_objects.html"><strong aria-hidden="true">3.5.</strong> Input objects</a></li><li class="chapter-item expanded "><a href="../types/scalars.html"><strong aria-hidden="true">3.6.</strong> Scalars</a></li></ol></li><li class="chapter-item expanded "><a href="../schema/index.html"><strong aria-hidden="true">4.</strong> Schema</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../schema/subscriptions.html"><strong aria-hidden="true">4.1.</strong> Subscriptions</a></li><li class="chapter-item expanded "><a href="../schema/introspection.html"><strong aria-hidden="true">4.2.</strong> Introspection</a></li></ol></li><li class="chapter-item expanded "><a href="../serve/index.html"><strong aria-hidden="true">5.</strong> Serving</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../serve/batching.html"><strong aria-hidden="true">5.1.</strong> Batching</a></li></ol></li><li class="chapter-item expanded "><a href="../advanced/index.html"><strong aria-hidden="true">6.</strong> Advanced Topics</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../advanced/implicit_and_explicit_null.html"><strong aria-hidden="true">6.1.</strong> Implicit and explicit null</a></li><li class="chapter-item expanded "><a href="../advanced/n_plus_1.html"><strong aria-hidden="true">6.2.</strong> N+1 problem</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../advanced/dataloader.html"><strong aria-hidden="true">6.2.1.</strong> DataLoader</a></li><li class="chapter-item expanded "><a href="../advanced/lookahead.html"><strong aria-hidden="true">6.2.2.</strong> Look-ahead</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../advanced/eager_loading.html"><strong aria-hidden="true">6.2.2.1.</strong> Eager loading</a></li></ol></li></ol></li></ol></li></ol>
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<h1 id="interfaces"><a class="header" href="#interfaces">Interfaces</a></h1>
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<blockquote>
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<p><a href="https://spec.graphql.org/October2021#sec-Interfaces">GraphQL interfaces</a> represent a list of named <a href="https://spec.graphql.org/October2021#sec-Language.Fields">fields</a> and their <a href="https://spec.graphql.org/October2021#sec-Language.Arguments">arguments</a>. <a href="https://spec.graphql.org/October2021#sec-Objects">GraphQL objects</a> and <a href="https://spec.graphql.org/October2021#sec-Interfaces">interfaces</a> can then implement these <a href="https://spec.graphql.org/October2021#sec-Interfaces">interfaces</a> which requires that the implementing type will define all <a href="https://spec.graphql.org/October2021#sec-Language.Fields">fields</a> defined by those <a href="https://spec.graphql.org/October2021#sec-Interfaces">interfaces</a>.</p>
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</blockquote>
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<p><a href="https://spec.graphql.org/October2021#sec-Interfaces">GraphQL interfaces</a> map well to interfaces known from common object-oriented languages such as Java or C#, but <a href="https://www.rust-lang.org">Rust</a>, unfortunately, has no concept that maps perfectly to them. The nearest analogue of <a href="https://spec.graphql.org/October2021#sec-Interfaces">GraphQL interfaces</a> are <a href="https://doc.rust-lang.org/reference/items/traits.html#traits">Rust traits</a>, but the main difference is that in <a href="https://graphql.org">GraphQL</a> an <a href="https://spec.graphql.org/October2021#sec-Interfaces">interface type</a> serves both as an <em>abstraction</em> and a <em>boxed value (dispatchable to concrete implementers)</em>, while in <a href="https://www.rust-lang.org">Rust</a>, a <a href="https://doc.rust-lang.org/reference/items/traits.html#traits">trait</a> is an <em>abstraction only</em>, and <em>to represent such a boxed value a separate type is required</em>, like a <a href="https://doc.rust-lang.org/reference/types/trait-object.html#trait-objects">trait object</a> or an <a href="https://doc.rust-lang.org/reference/items/enumerations.html#enumerations">enum</a> consisting of implementer types, because <a href="https://doc.rust-lang.org/reference/items/traits.html#traits">Rust trait</a> doesn't represent a type itself, and so, can have no values.</p>
|
|
<p>Another notable difference is that <a href="https://spec.graphql.org/October2021#sec-Interfaces">GraphQL interfaces</a> are more like <a href="https://en.wikipedia.org/wiki/Structural_type_system">structurally-typed</a> contracts: they <em>only declare a list of <a href="https://spec.graphql.org/October2021#sec-Language.Fields">fields</a></em> a <a href="https://graphql.org">GraphQL</a> type should already have. <a href="https://doc.rust-lang.org/reference/items/traits.html#traits">Rust traits</a>, on the other hand, are <a href="https://en.wikipedia.org/wiki/Type_class">type classes</a>, which don't really care about existing methods, but, rather, <em>require to provide implementations for required methods</em> despite the fact whether the type already has such methods or not. This difference makes the <a href="https://doc.rust-lang.org/reference/items/implementations.html#trait-implementations">trait implementation</a> not a good fit for expressing a <a href="https://spec.graphql.org/October2021#sec-Interfaces">GraphQL interface</a> implementation, because <em>we don't really need to implement any <a href="https://spec.graphql.org/October2021#sec-Language.Fields">fields</a></em>, the <a href="https://graphql.org">GraphQL</a> type implementing a <a href="https://spec.graphql.org/October2021#sec-Interfaces">GraphQL interface</a> has those <a href="https://spec.graphql.org/October2021#sec-Language.Fields">fields</a> already. <em>We only need to check that <a href="https://spec.graphql.org/October2021#sec-Language.Fields">fields'</a> signatures match</em>.</p>
|
|
<p>That's why <a href="https://docs.rs/juniper">Juniper</a> takes the following approach to represent <a href="https://spec.graphql.org/October2021#sec-Interfaces">GraphQL interfaces</a>, which consists of two parts:</p>
|
|
<ol>
|
|
<li>Either a <a href="https://doc.rust-lang.org/reference/items/structs.html">struct</a>, or a <a href="https://doc.rust-lang.org/reference/items/traits.html#traits">trait</a> (in case <a href="https://spec.graphql.org/October2021#sec-Language.Fields">fields</a> have <a href="https://spec.graphql.org/October2021#sec-Language.Arguments">arguments</a>), which acts only as a blueprint describing the required list of <a href="https://spec.graphql.org/October2021#sec-Language.Fields">fields</a>, and is not used in runtime at all.</li>
|
|
<li>An auto-generated <a href="https://doc.rust-lang.org/reference/items/enumerations.html#enumerations">enum</a>, representing a dispatchable value-type for the <a href="https://spec.graphql.org/October2021#sec-Interfaces">GraphQL interfaces</a>, which may be referred and returned by other <a href="https://spec.graphql.org/October2021#sec-Language.Fields">fields</a>.</li>
|
|
</ol>
|
|
<p>This may be done by using either the <a href="https://docs.rs/juniper/0.16.0/juniper/attr.graphql_interface.html"><code>#[graphql_interface]</code> attribute</a> or the <a href="https://docs.rs/juniper/0.16.0/juniper/derive.GraphQLInterface.html"><code>#[derive(GraphQLInterface)]</code></a>:</p>
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">extern crate juniper;
|
|
</span><span class="boring">use juniper::{graphql_interface, GraphQLInterface, GraphQLObject};
|
|
</span><span class="boring">
|
|
</span>// By default a `CharacterValue` enum is generated by macro to represent
|
|
// values of this GraphQL interface.
|
|
#[derive(GraphQLInterface)]
|
|
#[graphql(for = Human)] // enumerating all implementers is mandatory
|
|
struct Character {
|
|
id: String,
|
|
}
|
|
|
|
// Using a trait to describe the required fields is fine too.
|
|
#[graphql_interface]
|
|
#[graphql(enum = HasHomeEnum, for = Human)]
|
|
// ^^^^ the generated value-type enum can be renamed, if required
|
|
trait HasHome {
|
|
fn home_planet(&self) -> &str;
|
|
}
|
|
|
|
#[derive(GraphQLObject)]
|
|
#[graphql(impl = [CharacterValue, HasHomeEnum])]
|
|
// ^^^^^^^^^^^^^^ ^^^^^^^^^^^
|
|
// Notice the enum type names, neither the trait name nor the struct name
|
|
// is used to refer the GraphQL interface.
|
|
struct Human {
|
|
id: String, // also resolves `Character.id` field
|
|
home_planet: String, // also resolves `HasHome.homePlanet` field
|
|
}
|
|
<span class="boring">
|
|
</span><span class="boring">fn main() {}</span></code></pre></pre>
|
|
<h3 id="interfaces-implementing-other-interfaces"><a class="header" href="#interfaces-implementing-other-interfaces">Interfaces implementing other interfaces</a></h3>
|
|
<p><a href="https://graphql.org">GraphQL</a> allows implementing <a href="https://spec.graphql.org/October2021#sec-Interfaces">interfaces</a> on other <a href="https://spec.graphql.org/October2021#sec-Interfaces">interfaces</a> in addition to <a href="https://spec.graphql.org/October2021#sec-Objects">objects</a>:</p>
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">extern crate juniper;
|
|
</span><span class="boring">use juniper::{graphql_object, GraphQLInterface, ID};
|
|
</span><span class="boring">
|
|
</span>#[derive(GraphQLInterface)]
|
|
#[graphql(for = [HumanValue, Luke])]
|
|
struct Node {
|
|
id: ID,
|
|
}
|
|
|
|
#[derive(GraphQLInterface)]
|
|
#[graphql(impl = NodeValue, for = Luke)]
|
|
struct Human {
|
|
id: ID,
|
|
home_planet: String,
|
|
}
|
|
|
|
struct Luke {
|
|
id: ID,
|
|
}
|
|
|
|
#[graphql_object]
|
|
#[graphql(impl = [HumanValue, NodeValue])]
|
|
impl Luke {
|
|
fn id(&self) -> &ID {
|
|
&self.id
|
|
}
|
|
|
|
// As `String` and `&str` aren't distinguished by GraphQL spec and
|
|
// represent the same `!String` GraphQL scalar, we can use them
|
|
// interchangeably. The same is applied for `Cow<'a, str>`.
|
|
// ⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄
|
|
fn home_planet() -> &'static str {
|
|
"Tatooine"
|
|
}
|
|
}
|
|
<span class="boring">
|
|
</span><span class="boring">fn main() {}</span></code></pre></pre>
|
|
<blockquote>
|
|
<p><strong>NOTE</strong>: Every <a href="https://spec.graphql.org/October2021#sec-Interfaces">interface</a> has to specify all other <a href="https://spec.graphql.org/October2021#sec-Interfaces">interfaces</a>/<a href="https://spec.graphql.org/October2021#sec-Interfaces">objects</a> it implements or implemented for. Missing one of <code>for = </code> or <code>impl = </code> attribute arguments is a <strong>compile-time error</strong>.</p>
|
|
<pre><pre class="playground"><code class="language-rust compile_fail edition2021"><span class="boring">extern crate juniper;
|
|
</span><span class="boring">use juniper::{GraphQLInterface, GraphQLObject};
|
|
</span><span class="boring">
|
|
</span>#[derive(GraphQLObject)]
|
|
pub struct ObjA {
|
|
id: String,
|
|
}
|
|
|
|
#[derive(GraphQLInterface)]
|
|
#[graphql(for = ObjA)]
|
|
// ^^^^^^^^^^ the evaluated program panicked at
|
|
// 'Failed to implement interface `Character` on `ObjA`: missing interface
|
|
// reference in implementer's `impl` attribute.'
|
|
struct Character {
|
|
id: String,
|
|
}
|
|
<span class="boring">
|
|
</span><span class="boring">fn main() {}</span></code></pre></pre>
|
|
</blockquote>
|
|
<h3 id="subtyping-and-additional-nullable-arguments"><a class="header" href="#subtyping-and-additional-nullable-arguments">Subtyping and additional <code>null</code>able arguments</a></h3>
|
|
<p><a href="https://graphql.org">GraphQL</a> allows implementers (both <a href="https://spec.graphql.org/October2021#sec-Objects">objects</a> and other <a href="https://spec.graphql.org/October2021#sec-Interfaces">interfaces</a>) to return "subtypes" instead of an original value. Basically, this allows to impose additional bounds on the implementation.</p>
|
|
<p>Valid "subtypes" are:</p>
|
|
<ul>
|
|
<li><a href="https://spec.graphql.org/October2021#sec-Interfaces">interface</a> implementer instead of an <a href="https://spec.graphql.org/October2021#sec-Interfaces">interface</a> itself:
|
|
<ul>
|
|
<li><code>I implements T</code> in place of a <code>T</code>;</li>
|
|
<li><code>Vec<I implements T></code> in place of a <code>Vec<T></code>.</li>
|
|
</ul>
|
|
</li>
|
|
<li><a href="https://spec.graphql.org/October2021#sec-Non-Null">non-<code>null</code></a> value in place of a <code>null</code>able:
|
|
<ul>
|
|
<li><code>T</code> in place of a <code>Option<T></code>;</li>
|
|
<li><code>Vec<T></code> in place of a <code>Vec<Option<T>></code>.</li>
|
|
</ul>
|
|
</li>
|
|
</ul>
|
|
<p>These rules are recursively applied, so <code>Vec<Vec<I implements T>></code> is a valid "subtype" of a <code>Option<Vec<Option<Vec<Option<T>>>>></code>.</p>
|
|
<p>Also, <a href="https://graphql.org">GraphQL</a> allows implementers to add <code>null</code>able <a href="https://spec.graphql.org/October2021#sec-Language.Arguments">field arguments</a>, which aren't present on an original interface.</p>
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">extern crate juniper;
|
|
</span><span class="boring">use juniper::{graphql_interface, graphql_object, GraphQLInterface, ID};
|
|
</span><span class="boring">
|
|
</span>#[derive(GraphQLInterface)]
|
|
#[graphql(for = [HumanValue, Luke])]
|
|
struct Node {
|
|
id: ID,
|
|
}
|
|
|
|
#[derive(GraphQLInterface)]
|
|
#[graphql(for = HumanConnectionValue)]
|
|
struct Connection {
|
|
nodes: Vec<NodeValue>,
|
|
}
|
|
|
|
#[derive(GraphQLInterface)]
|
|
#[graphql(impl = NodeValue, for = Luke)]
|
|
struct Human {
|
|
id: ID,
|
|
home_planet: String,
|
|
}
|
|
|
|
#[derive(GraphQLInterface)]
|
|
#[graphql(impl = ConnectionValue)]
|
|
struct HumanConnection {
|
|
nodes: Vec<HumanValue>,
|
|
// ^^^^^^^^^^ notice not `NodeValue`
|
|
// This can happen, because every `Human` is a `Node` too, so we just
|
|
// impose additional bounds, which still can be resolved with
|
|
// `... on Connection { nodes }` syntax.
|
|
}
|
|
|
|
struct Luke {
|
|
id: ID,
|
|
}
|
|
|
|
#[graphql_object]
|
|
#[graphql(impl = [HumanValue, NodeValue])]
|
|
impl Luke {
|
|
fn id(&self) -> &ID {
|
|
&self.id
|
|
}
|
|
|
|
fn home_planet(language: Option<String>) -> &'static str {
|
|
// ^^^^^^^^^^^^^^
|
|
// Notice additional `null`able field argument, which is missing on
|
|
// `Human`. Resolving `...on Human { homePlanet }` will provide `None`
|
|
// for this argument (default argument value).
|
|
match language.as_deref() {
|
|
None | Some("en") => "Tatooine",
|
|
Some("ko") => "타투인",
|
|
_ => unimplemented!(),
|
|
}
|
|
}
|
|
}
|
|
<span class="boring">
|
|
</span><span class="boring">fn main() {}</span></code></pre></pre>
|
|
<blockquote>
|
|
<p><strong>NOTE</strong>: Violating <a href="https://graphql.org">GraphQL</a> "subtyping" or additional <code>null</code>able <a href="https://spec.graphql.org/October2021#sec-Language.Arguments">argument</a> rules is a <strong>compile-time error</strong>.</p>
|
|
<pre><pre class="playground"><code class="language-rust compile_fail edition2021"><span class="boring">extern crate juniper;
|
|
</span><span class="boring">use juniper::{graphql_object, GraphQLInterface};
|
|
</span><span class="boring">
|
|
</span>pub struct ObjA {
|
|
id: String,
|
|
}
|
|
|
|
#[graphql_object]
|
|
#[graphql(impl = CharacterValue)]
|
|
impl ObjA {
|
|
fn id(&self, is_present: bool) -> &str {
|
|
// ^^ the evaluated program panicked at
|
|
// 'Failed to implement interface `Character` on `ObjA`: Field `id`: Argument
|
|
// `isPresent` of type `Boolean!` isn't present on the interface and so has
|
|
// to be nullable.'
|
|
is_present.then_some(&self.id).unwrap_or("missing")
|
|
}
|
|
}
|
|
|
|
#[derive(GraphQLInterface)]
|
|
#[graphql(for = ObjA)]
|
|
struct Character {
|
|
id: String,
|
|
}
|
|
<span class="boring">
|
|
</span><span class="boring">fn main() {}</span></code></pre></pre>
|
|
<pre><pre class="playground"><code class="language-rust compile_fail edition2021"><span class="boring">extern crate juniper;
|
|
</span><span class="boring">use juniper::{GraphQLInterface, GraphQLObject};
|
|
</span><span class="boring">
|
|
</span>#[derive(GraphQLObject)]
|
|
#[graphql(impl = CharacterValue)]
|
|
pub struct ObjA {
|
|
id: Vec<String>,
|
|
// ^^ the evaluated program panicked at
|
|
// 'Failed to implement interface `Character` on `ObjA`: Field `id`:
|
|
// implementer is expected to return a subtype of interface's return
|
|
// object: `[String!]!` is not a subtype of `String!`.'
|
|
}
|
|
|
|
#[derive(GraphQLInterface)]
|
|
#[graphql(for = ObjA)]
|
|
struct Character {
|
|
id: String,
|
|
}
|
|
<span class="boring">
|
|
</span><span class="boring">fn main() {}</span></code></pre></pre>
|
|
</blockquote>
|
|
<h3 id="default-arguments"><a class="header" href="#default-arguments">Default arguments</a></h3>
|
|
<p><a href="objects/complex_fields.html#default-arguments">Similarly to GraphQL object fields</a>, <a href="https://spec.graphql.org/October2021#sec-Language.Fields">GraphQL arguments</a> of <a href="https://spec.graphql.org/October2021#sec-Interfaces">interfaces</a> are able to have default values, though <a href="https://www.rust-lang.org">Rust</a> doesn't have such notion:</p>
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">extern crate juniper;
|
|
</span><span class="boring">use juniper::graphql_interface;
|
|
</span><span class="boring">
|
|
</span>#[graphql_interface]
|
|
trait Person {
|
|
fn field1(
|
|
// Default value can be any valid Rust expression, including a function
|
|
// call, etc.
|
|
#[graphql(default = true)]
|
|
arg1: bool,
|
|
// If default expression is not specified, then the `Default::default()`
|
|
// value is used.
|
|
#[graphql(default)]
|
|
arg2: i32,
|
|
) -> String;
|
|
}
|
|
<span class="boring">
|
|
</span><span class="boring">fn main() {}</span></code></pre></pre>
|
|
<h3 id="renaming"><a class="header" href="#renaming">Renaming</a></h3>
|
|
<p>Just as with <a href="objects/index.html#renaming">defining GraphQL objects</a>, by default, <a href="https://spec.graphql.org/October2021#sec-Language.Fields">fields</a> are converted from <a href="https://www.rust-lang.org">Rust</a>'s standard <code>snake_case</code> naming convention into <a href="https://graphql.org">GraphQL</a>'s <code>camelCase</code> convention:</p>
|
|
<p>We can override the name by using the <code>#[graphql(name = "...")]</code> attribute:</p>
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">extern crate juniper;
|
|
</span><span class="boring">use juniper::{graphql_interface, GraphQLInterface};
|
|
</span><span class="boring">
|
|
</span>#[derive(GraphQLInterface)]
|
|
#[graphql(name = "CharacterInterface")]
|
|
struct Character { // exposed as `CharacterInterface` in GraphQL schema
|
|
#[graphql(name = "myCustomFieldName")]
|
|
renamed_field: bool, // exposed as `myCustomFieldName` in GraphQL schema
|
|
}
|
|
|
|
#[graphql_interface]
|
|
#[graphql(name = "PersonInterface")]
|
|
trait Person { // exposed as `PersonInterface` in GraphQL schema
|
|
#[graphql(name = "myCustomFieldName")]
|
|
fn renamed_field( // exposed as `myCustomFieldName` in GraphQL schema
|
|
#[graphql(name = "myArgument")]
|
|
renamed_argument: bool, // exposed as `myArgument` in GraphQL schema
|
|
) -> bool;
|
|
}
|
|
<span class="boring">
|
|
</span><span class="boring">fn main() {}</span></code></pre></pre>
|
|
<p>Or provide a different renaming policy for all the defined <a href="https://spec.graphql.org/October2021#sec-Language.Fields">fields</a>:</p>
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">extern crate juniper;
|
|
</span><span class="boring">use juniper::graphql_interface;
|
|
</span><span class="boring">
|
|
</span>#[graphql_interface]
|
|
#[graphql(rename_all = "none")] // disables any renaming
|
|
trait Person {
|
|
fn renamed_field( // exposed as `renamed_field` in GraphQL schema
|
|
renamed_argument: bool, // exposed as `renamed_argument` in GraphQL schema
|
|
) -> bool;
|
|
}
|
|
<span class="boring">
|
|
</span><span class="boring">fn main() {}</span></code></pre></pre>
|
|
<blockquote>
|
|
<p><strong>TIP</strong>: Supported policies are: <code>SCREAMING_SNAKE_CASE</code>, <code>camelCase</code> and <code>none</code> (disables any renaming).</p>
|
|
</blockquote>
|
|
<h3 id="documentation-and-deprecation"><a class="header" href="#documentation-and-deprecation">Documentation and deprecation</a></h3>
|
|
<p>Similarly, <a href="https://spec.graphql.org/October2021#sec-Language.Fields">GraphQL fields</a> of <a href="https://spec.graphql.org/October2021#sec-Interfaces">interfaces</a> may also be <a href="https://spec.graphql.org/October2021#sec-Descriptions">documented</a> and <a href="https://spec.graphql.org/October2021#sec--deprecated">deprecated</a> via <code>#[graphql(description = "...")]</code> and <code>#[graphql(deprecated = "...")]</code>/<a href="https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-deprecated-attribute"><code>#[deprecated]</code></a> attributes:</p>
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">extern crate juniper;
|
|
</span><span class="boring">use juniper::graphql_interface;
|
|
</span><span class="boring">
|
|
</span>/// This doc comment is visible only in Rust API docs.
|
|
#[graphql_interface]
|
|
#[graphql(description = "This description overwrites the one from doc comment.")]
|
|
trait Person {
|
|
/// This doc comment is visible only in Rust API docs.
|
|
#[graphql(description = "This description is visible only in GraphQL schema.")]
|
|
fn empty() -> &'static str;
|
|
|
|
#[graphql(desc = "This description is visible only in GraphQL schema.")]
|
|
// ^^^^ shortcut for a `description` argument
|
|
fn field(
|
|
#[graphql(desc = "This description is visible only in GraphQL schema.")]
|
|
arg: bool,
|
|
) -> bool;
|
|
|
|
/// This doc comment is visible in both Rust API docs and GraphQL schema
|
|
/// descriptions.
|
|
#[graphql(deprecated = "Just because.")]
|
|
fn deprecated_graphql() -> bool;
|
|
|
|
// Standard Rust's `#[deprecated]` attribute works too!
|
|
#[deprecated(note = "Reason is optional, btw!")]
|
|
fn deprecated_standard() -> bool; // has no description in GraphQL schema
|
|
}
|
|
<span class="boring">
|
|
</span><span class="boring">fn main() {}</span></code></pre></pre>
|
|
<blockquote>
|
|
<p><strong>NOTE</strong>: Only <a href="https://spec.graphql.org/October2021#sec-Interfaces">GraphQL interface</a>/<a href="https://spec.graphql.org/October2021#sec-Objects">object</a> fields and <a href="https://spec.graphql.org/October2021#sec-Enums">GraphQL enum</a> values can be <a href="https://spec.graphql.org/October2021#sec--deprecated">deprecated</a>.</p>
|
|
</blockquote>
|
|
<h3 id="ignoring"><a class="header" href="#ignoring">Ignoring</a></h3>
|
|
<p>By default, all <a href="https://doc.rust-lang.org/reference/items/structs.html">struct</a> fields or <a href="https://doc.rust-lang.org/reference/items/traits.html#traits">trait</a> methods are considered as <a href="https://spec.graphql.org/October2021#sec-Language.Fields">GraphQL fields</a>. If a helper method is needed, or it should be ignored for some reason, then it should be marked with the <code>#[graphql(ignore)]</code> attribute:</p>
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(dead_code)]
|
|
</span><span class="boring">extern crate juniper;
|
|
</span><span class="boring">use std::marker::PhantomPinned;
|
|
</span><span class="boring">use juniper::{graphql_interface, GraphQLInterface};
|
|
</span><span class="boring">
|
|
</span>#[derive(GraphQLInterface)]
|
|
struct Character {
|
|
id: i32,
|
|
#[graphql(ignore)]
|
|
_pin: PhantomPinned,
|
|
}
|
|
|
|
#[graphql_interface]
|
|
trait Person {
|
|
fn name(&self) -> &str;
|
|
|
|
fn age(&self) -> i32;
|
|
|
|
#[graphql(ignore)]
|
|
fn hidden_from_graphql(&self) {
|
|
// Ignored methods are allowed to have a default implementation!
|
|
}
|
|
|
|
#[graphql(skip)]
|
|
// ^^^^ alternative naming, up to your preference
|
|
fn also_hidden_from_graphql(&self);
|
|
}
|
|
<span class="boring">
|
|
</span><span class="boring">fn main() {}</span></code></pre></pre>
|
|
<blockquote>
|
|
<p><strong>TIP</strong>: See more available features in the API docs of the <a href="https://docs.rs/juniper/0.16.0/juniper/attr.graphql_interface.html"><code>#[graphql_interface]</code></a> attribute.</p>
|
|
</blockquote>
|
|
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