297 lines
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297 lines
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<ol class="chapter"><li class="chapter-item expanded "><a href="../index.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/defining_objects.html"><strong aria-hidden="true">3.1.</strong> Defining 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/using_contexts.html"><strong aria-hidden="true">3.1.2.</strong> Using contexts</a></li><li class="chapter-item expanded "><a href="../types/objects/error_handling.html"><strong aria-hidden="true">3.1.3.</strong> Error handling</a></li></ol></li><li class="chapter-item expanded "><a href="../types/other-index.html"><strong aria-hidden="true">3.2.</strong> Other types</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../types/enums.html"><strong aria-hidden="true">3.2.1.</strong> Enums</a></li><li class="chapter-item expanded "><a href="../types/interfaces.html"><strong aria-hidden="true">3.2.2.</strong> Interfaces</a></li><li class="chapter-item expanded "><a href="../types/input_objects.html"><strong aria-hidden="true">3.2.3.</strong> Input objects</a></li><li class="chapter-item expanded "><a href="../types/scalars.html"><strong aria-hidden="true">3.2.4.</strong> Scalars</a></li><li class="chapter-item expanded "><a href="../types/unions.html"><strong aria-hidden="true">3.2.5.</strong> Unions</a></li></ol></li></ol></li><li class="chapter-item expanded "><a href="../schema/schemas_and_mutations.html"><strong aria-hidden="true">4.</strong> Schemas and mutations</a></li><li class="chapter-item expanded "><a href="../servers/index.html"><strong aria-hidden="true">5.</strong> Adding A Server</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../servers/official.html"><strong aria-hidden="true">5.1.</strong> Official Server Integrations</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../servers/warp.html"><strong aria-hidden="true">5.1.1.</strong> Warp</a></li><li class="chapter-item expanded "><a href="../servers/rocket.html"><strong aria-hidden="true">5.1.2.</strong> Rocket</a></li><li class="chapter-item expanded "><a href="../servers/hyper.html"><strong aria-hidden="true">5.1.3.</strong> Hyper</a></li></ol></li><li class="chapter-item expanded "><a href="../servers/third-party.html"><strong aria-hidden="true">5.2.</strong> Third Party Integrations</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/introspection.html" class="active"><strong aria-hidden="true">6.1.</strong> Introspection</a></li><li class="chapter-item expanded "><a href="../advanced/non_struct_objects.html"><strong aria-hidden="true">6.2.</strong> Non-struct objects</a></li><li class="chapter-item expanded "><a href="../advanced/implicit_and_explicit_null.html"><strong aria-hidden="true">6.3.</strong> Implicit and explicit null</a></li><li class="chapter-item expanded "><a href="../advanced/objects_and_generics.html"><strong aria-hidden="true">6.4.</strong> Objects and generics</a></li><li class="chapter-item expanded "><a href="../advanced/multiple_ops_per_request.html"><strong aria-hidden="true">6.5.</strong> Multiple operations per request</a></li><li class="chapter-item expanded "><a href="../advanced/dataloaders.html"><strong aria-hidden="true">6.6.</strong> Dataloaders</a></li><li class="chapter-item expanded "><a href="../advanced/subscriptions.html"><strong aria-hidden="true">6.7.</strong> Subscriptions</a></li></ol></li></ol>
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<h1 class="menu-title">Juniper Book (GraphQL server for Rust)</h1>
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<main>
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<h1 id="introspection"><a class="header" href="#introspection">Introspection</a></h1>
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<p>GraphQL defines a special built-in top-level field called <code>__schema</code>. Querying
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for this field allows one to <a href="https://graphql.org/learn/introspection/">introspect the schema</a>
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at runtime to see what queries and mutations the GraphQL server supports.</p>
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<p>Because introspection queries are just regular GraphQL queries, Juniper supports
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them natively. For example, to get all the names of the types supported one
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could execute the following query against Juniper:</p>
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<pre><code class="language-graphql">{
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__schema {
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types {
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name
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}
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}
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}
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</code></pre>
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<h2 id="schema-introspection-output-as-json"><a class="header" href="#schema-introspection-output-as-json">Schema introspection output as JSON</a></h2>
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<p>Many client libraries and tools in the GraphQL ecosystem require a complete
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representation of the server schema. Often this representation is in JSON and
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referred to as <code>schema.json</code>. A complete representation of the schema can be
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produced by issuing a specially crafted introspection query.</p>
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<p>Juniper provides a convenience function to introspect the entire schema. The
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result can then be converted to JSON for use with tools and libraries such as
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<a href="https://github.com/graphql-rust/graphql-client">graphql-client</a>:</p>
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<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused_variables)]
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</span><span class="boring">extern crate juniper;
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</span><span class="boring">extern crate serde_json;
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</span>use juniper::{
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graphql_object, EmptyMutation, EmptySubscription, FieldResult,
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GraphQLObject, IntrospectionFormat,
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};
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// Define our schema.
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#[derive(GraphQLObject)]
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struct Example {
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id: String,
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}
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struct Context;
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impl juniper::Context for Context {}
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struct Query;
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#[graphql_object(context = Context)]
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impl Query {
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fn example(id: String) -> FieldResult<Example> {
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unimplemented!()
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}
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}
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type Schema = juniper::RootNode<
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'static,
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Query,
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EmptyMutation<Context>,
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EmptySubscription<Context>
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>;
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fn main() {
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// Create a context object.
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let ctx = Context;
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// Run the built-in introspection query.
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let (res, _errors) = juniper::introspect(
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&Schema::new(Query, EmptyMutation::new(), EmptySubscription::new()),
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&ctx,
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IntrospectionFormat::default(),
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).unwrap();
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// Convert introspection result to json.
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let json_result = serde_json::to_string_pretty(&res);
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assert!(json_result.is_ok());
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}</code></pre></pre>
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