63 lines
2 KiB
Markdown
63 lines
2 KiB
Markdown
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# Schemas
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A schema consists of two types: a query object and a mutation object (Juniper
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does not support subscriptions yet). These two define the root query fields
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and mutations of the schema, respectively.
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Both query and mutation objects are regular GraphQL objects, defined like any
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other object in Juniper. The mutation object, however, is optional since schemas
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can be read-only.
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In Juniper, the `RootNode` type represents a schema. You usually don't have to
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create this object yourself: see the framework integrations for [Iron](iron.md)
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and [Rocket](rocket.md) how schemas are created together with the handlers
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themselves.
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When the schema is first created, Juniper will traverse the entire object graph
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and register all types it can find. This means that if you define a GraphQL
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object somewhere but never references it, it will not be exposed in a schema.
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## The query root
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The query root is just a GraphQL object. You define it like any other GraphQL
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object in Juniper, most commonly using the `graphql_object!` macro:
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```rust
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# #[macro_use] extern crate juniper;
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# #[macro_use] extern crate juniper_codegen;
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# use juniper::FieldResult;
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# #[derive(GraphQLObject)] struct User { name: String }
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struct Root;
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graphql_object!(Root: () |&self| {
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field userWithUsername(username: String) -> FieldResult<Option<User>> {
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// Look up user in database...
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# unimplemented!()
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}
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});
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# fn main() { }
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```
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## Mutations
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Mutations are _also_ just GraphQL objects. Each mutation is a single field that
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usually performs some mutating side-effect, such as updating a database.
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```rust
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# #[macro_use] extern crate juniper;
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# #[macro_use] extern crate juniper_codegen;
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# use juniper::FieldResult;
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# #[derive(GraphQLObject)] struct User { name: String }
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struct Mutations;
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graphql_object!(Mutations: () |&self| {
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field signUpUser(name: String, email: String) -> FieldResult<User> {
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// Validate inputs and save user in database...
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# unimplemented!()
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}
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});
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# fn main() { }
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```
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