deploy: 9ca2364bfe
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tyranron
parent
3db1a1ba9c
commit
8a883b62fe
4 changed files with 348 additions and 2 deletions
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@ -1411,6 +1411,179 @@ struct Human {
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<span class="boring">
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</span><span class="boring">fn main() {}
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</span></code></pre></pre>
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<h3 id="interfaces-implementing-other-interfaces"><a class="header" href="#interfaces-implementing-other-interfaces">Interfaces implementing other interfaces</a></h3>
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<p>GraphQL allows implementing interfaces on other interfaces in addition to objects.</p>
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<pre><pre class="playground"><code class="language-rust edition2018"><span class="boring">extern crate juniper;
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</span>use juniper::{graphql_interface, graphql_object, ID};
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#[graphql_interface(for = [HumanValue, Luke])]
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struct Node {
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id: ID,
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}
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#[graphql_interface(impl = NodeValue, for = Luke)]
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struct Human {
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id: ID,
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home_planet: String,
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}
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struct Luke {
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id: ID,
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}
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#[graphql_object(impl = [HumanValue, NodeValue])]
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impl Luke {
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fn id(&self) -> &ID {
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&self.id
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}
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// As `String` and `&str` aren't distinguished by
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// GraphQL spec, you can use them interchangeably.
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// Same is applied for `Cow<'a, str>`.
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// ⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄
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fn home_planet() -> &'static str {
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"Tatooine"
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}
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}
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<span class="boring">
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</span><span class="boring">fn main() {}
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</span></code></pre></pre>
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<blockquote>
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<p><strong>NOTE:</strong> Every interface has to specify all other interfaces/objects it implements or implemented for. Missing one of <code>for = </code> or <code>impl = </code> attributes is a compile-time error.</p>
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</blockquote>
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<pre><code class="language-compile_fail"># extern crate juniper;
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use juniper::{graphql_interface, GraphQLObject};
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#[derive(GraphQLObject)]
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pub struct ObjA {
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id: String,
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}
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#[graphql_interface(for = ObjA)]
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// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at
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// 'Failed to implement interface `Character` on `ObjA`: missing interface reference in implementer's `impl` attribute.'
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struct Character {
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id: String,
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}
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fn main() {}
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</code></pre>
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<h3 id="graphql-subtyping-and-additional-nullable-fields"><a class="header" href="#graphql-subtyping-and-additional-nullable-fields">GraphQL subtyping and additional <code>null</code>able fields</a></h3>
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<p>GraphQL allows implementers (both objects and other interfaces) to return "subtypes" instead of an original value. Basically, this allows you to impose additional bounds on the implementation.</p>
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<p>Valid "subtypes" are:</p>
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<ul>
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<li>interface implementer instead of an interface itself:
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<ul>
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<li><code>I implements T</code> in place of a <code>T</code>;</li>
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<li><code>Vec<I implements T></code> in place of a <code>Vec<T></code>.</li>
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</ul>
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</li>
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<li>non-null value in place of a nullable:
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<ul>
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<li><code>T</code> in place of a <code>Option<T></code>;</li>
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<li><code>Vec<T></code> in place of a <code>Vec<Option<T>></code>.</li>
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</ul>
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</li>
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</ul>
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<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>
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<p>Also, GraphQL allows implementers to add <code>null</code>able fields, which aren't present on an original interface.</p>
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<pre><pre class="playground"><code class="language-rust edition2018"><span class="boring">extern crate juniper;
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</span>use juniper::{graphql_interface, graphql_object, ID};
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#[graphql_interface(for = [HumanValue, Luke])]
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struct Node {
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id: ID,
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}
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#[graphql_interface(for = HumanConnectionValue)]
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struct Connection {
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nodes: Vec<NodeValue>,
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}
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#[graphql_interface(impl = NodeValue, for = Luke)]
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struct Human {
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id: ID,
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home_planet: String,
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}
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#[graphql_interface(impl = ConnectionValue)]
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struct HumanConnection {
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nodes: Vec<HumanValue>,
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// ^^^^^^^^^^ notice not `NodeValue`
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// This can happen, because every `Human` is a `Node` too, so we are just
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// imposing additional bounds, which still can be resolved with
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// `... on Connection { nodes }`.
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}
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struct Luke {
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id: ID,
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}
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#[graphql_object(impl = [HumanValue, NodeValue])]
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impl Luke {
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fn id(&self) -> &ID {
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&self.id
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}
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fn home_planet(language: Option<String>) -> &'static str {
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// ^^^^^^^^^^^^^^
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// Notice additional `null`able field, which is missing on `Human`.
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// Resolving `...on Human { homePlanet }` will provide `None` for this
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// argument.
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match language.as_deref() {
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None | Some("en") => "Tatooine",
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Some("ko") => "타투인",
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_ => todo!(),
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}
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}
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}
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<span class="boring">
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</span><span class="boring">fn main() {}
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</span></code></pre></pre>
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<p>Violating GraphQL "subtyping" or additional nullable field rules is a compile-time error.</p>
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<pre><code class="language-compile_fail"># extern crate juniper;
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use juniper::{graphql_interface, graphql_object};
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pub struct ObjA {
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id: String,
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}
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#[graphql_object(impl = CharacterValue)]
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impl ObjA {
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fn id(&self, is_present: bool) -> &str {
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// ^^ the evaluated program panicked at
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// 'Failed to implement interface `Character` on `ObjA`: Field `id`: Argument `isPresent` of type `Boolean!`
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// isn't present on the interface and so has to be nullable.'
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is_present.then(|| self.id.as_str()).unwrap_or("missing")
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}
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}
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#[graphql_interface(for = ObjA)]
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struct Character {
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id: String,
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}
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#
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# fn main() {}
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</code></pre>
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<pre><code class="language-compile_fail"># extern crate juniper;
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use juniper::{graphql_interface, GraphQLObject};
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#[derive(GraphQLObject)]
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#[graphql(impl = CharacterValue)]
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pub struct ObjA {
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id: Vec<String>,
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// ^^ the evaluated program panicked at
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// 'Failed to implement interface `Character` on `ObjA`: Field `id`: implementor is expected to return a subtype of
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// interface's return object: `[String!]!` is not a subtype of `String!`.'
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}
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#[graphql_interface(for = ObjA)]
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struct Character {
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id: String,
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}
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#
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# fn main() {}
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</code></pre>
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<h3 id="ignoring-trait-methods"><a class="header" href="#ignoring-trait-methods">Ignoring trait methods</a></h3>
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<p>We may want to omit some trait methods to be assumed as <a href="https://spec.graphql.org/June2018/#sec-Interfaces">GraphQL interface</a> fields and ignore them.</p>
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<pre><pre class="playground"><code class="language-rust edition2018"><span class="boring">extern crate juniper;
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File diff suppressed because one or more lines are too long
File diff suppressed because one or more lines are too long
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@ -192,6 +192,179 @@ struct Human {
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<span class="boring">
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</span><span class="boring">fn main() {}
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</span></code></pre></pre>
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<h3 id="interfaces-implementing-other-interfaces"><a class="header" href="#interfaces-implementing-other-interfaces">Interfaces implementing other interfaces</a></h3>
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<p>GraphQL allows implementing interfaces on other interfaces in addition to objects.</p>
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<pre><pre class="playground"><code class="language-rust edition2018"><span class="boring">extern crate juniper;
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</span>use juniper::{graphql_interface, graphql_object, ID};
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#[graphql_interface(for = [HumanValue, Luke])]
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struct Node {
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id: ID,
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}
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#[graphql_interface(impl = NodeValue, for = Luke)]
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struct Human {
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id: ID,
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home_planet: String,
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}
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struct Luke {
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id: ID,
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}
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#[graphql_object(impl = [HumanValue, NodeValue])]
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impl Luke {
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fn id(&self) -> &ID {
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&self.id
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}
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// As `String` and `&str` aren't distinguished by
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// GraphQL spec, you can use them interchangeably.
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// Same is applied for `Cow<'a, str>`.
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// ⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄
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fn home_planet() -> &'static str {
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"Tatooine"
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}
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}
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<span class="boring">
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</span><span class="boring">fn main() {}
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</span></code></pre></pre>
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<blockquote>
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<p><strong>NOTE:</strong> Every interface has to specify all other interfaces/objects it implements or implemented for. Missing one of <code>for = </code> or <code>impl = </code> attributes is a compile-time error.</p>
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</blockquote>
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<pre><code class="language-compile_fail"># extern crate juniper;
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use juniper::{graphql_interface, GraphQLObject};
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#[derive(GraphQLObject)]
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pub struct ObjA {
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id: String,
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}
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#[graphql_interface(for = ObjA)]
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// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at
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// 'Failed to implement interface `Character` on `ObjA`: missing interface reference in implementer's `impl` attribute.'
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struct Character {
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id: String,
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}
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fn main() {}
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</code></pre>
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<h3 id="graphql-subtyping-and-additional-nullable-fields"><a class="header" href="#graphql-subtyping-and-additional-nullable-fields">GraphQL subtyping and additional <code>null</code>able fields</a></h3>
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<p>GraphQL allows implementers (both objects and other interfaces) to return "subtypes" instead of an original value. Basically, this allows you to impose additional bounds on the implementation.</p>
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<p>Valid "subtypes" are:</p>
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<ul>
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<li>interface implementer instead of an interface itself:
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<ul>
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<li><code>I implements T</code> in place of a <code>T</code>;</li>
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<li><code>Vec<I implements T></code> in place of a <code>Vec<T></code>.</li>
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</ul>
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</li>
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<li>non-null value in place of a nullable:
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<ul>
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<li><code>T</code> in place of a <code>Option<T></code>;</li>
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<li><code>Vec<T></code> in place of a <code>Vec<Option<T>></code>.</li>
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</ul>
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</li>
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</ul>
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<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>
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<p>Also, GraphQL allows implementers to add <code>null</code>able fields, which aren't present on an original interface.</p>
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<pre><pre class="playground"><code class="language-rust edition2018"><span class="boring">extern crate juniper;
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</span>use juniper::{graphql_interface, graphql_object, ID};
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#[graphql_interface(for = [HumanValue, Luke])]
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struct Node {
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id: ID,
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}
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#[graphql_interface(for = HumanConnectionValue)]
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struct Connection {
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nodes: Vec<NodeValue>,
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}
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#[graphql_interface(impl = NodeValue, for = Luke)]
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struct Human {
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id: ID,
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home_planet: String,
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}
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#[graphql_interface(impl = ConnectionValue)]
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struct HumanConnection {
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nodes: Vec<HumanValue>,
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// ^^^^^^^^^^ notice not `NodeValue`
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// This can happen, because every `Human` is a `Node` too, so we are just
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// imposing additional bounds, which still can be resolved with
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// `... on Connection { nodes }`.
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}
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struct Luke {
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id: ID,
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}
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#[graphql_object(impl = [HumanValue, NodeValue])]
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impl Luke {
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fn id(&self) -> &ID {
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&self.id
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}
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fn home_planet(language: Option<String>) -> &'static str {
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// ^^^^^^^^^^^^^^
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// Notice additional `null`able field, which is missing on `Human`.
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// Resolving `...on Human { homePlanet }` will provide `None` for this
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// argument.
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match language.as_deref() {
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None | Some("en") => "Tatooine",
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Some("ko") => "타투인",
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_ => todo!(),
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}
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}
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}
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<span class="boring">
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</span><span class="boring">fn main() {}
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</span></code></pre></pre>
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<p>Violating GraphQL "subtyping" or additional nullable field rules is a compile-time error.</p>
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<pre><code class="language-compile_fail"># extern crate juniper;
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use juniper::{graphql_interface, graphql_object};
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pub struct ObjA {
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id: String,
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}
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#[graphql_object(impl = CharacterValue)]
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impl ObjA {
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fn id(&self, is_present: bool) -> &str {
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// ^^ the evaluated program panicked at
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// 'Failed to implement interface `Character` on `ObjA`: Field `id`: Argument `isPresent` of type `Boolean!`
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// isn't present on the interface and so has to be nullable.'
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is_present.then(|| self.id.as_str()).unwrap_or("missing")
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}
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}
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#[graphql_interface(for = ObjA)]
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struct Character {
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id: String,
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}
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#
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# fn main() {}
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</code></pre>
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<pre><code class="language-compile_fail"># extern crate juniper;
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use juniper::{graphql_interface, GraphQLObject};
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#[derive(GraphQLObject)]
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#[graphql(impl = CharacterValue)]
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pub struct ObjA {
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id: Vec<String>,
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// ^^ the evaluated program panicked at
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// 'Failed to implement interface `Character` on `ObjA`: Field `id`: implementor is expected to return a subtype of
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// interface's return object: `[String!]!` is not a subtype of `String!`.'
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}
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#[graphql_interface(for = ObjA)]
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struct Character {
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id: String,
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}
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#
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# fn main() {}
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</code></pre>
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<h3 id="ignoring-trait-methods"><a class="header" href="#ignoring-trait-methods">Ignoring trait methods</a></h3>
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<p>We may want to omit some trait methods to be assumed as <a href="https://spec.graphql.org/June2018/#sec-Interfaces">GraphQL interface</a> fields and ignore them.</p>
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<pre><pre class="playground"><code class="language-rust edition2018"><span class="boring">extern crate juniper;
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