Crate juniper

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GraphQL

GraphQL is a data query language developed by Facebook intended to serve mobile and web application frontends.

Juniper makes it possible to write GraphQL servers in Rust that are type-safe and blazingly fast. We also try to make declaring and resolving GraphQL schemas as convenient as possible as Rust will allow.

Juniper does not include a web server - instead it provides building blocks to make integration with existing servers straightforward. It optionally provides a pre-built integration for the Iron and Rocket frameworks, including embedded Graphiql for easy debugging.

Cargo crate
API Reference
Book: Guides and Examples

Getting Started

The best place to get started is the Juniper Book, which contains guides with plenty of examples, covering all features of Juniper.

To get started quickly and get a feel for Juniper, check out the Quickstart section.

For specific information about macros, types and the Juniper api, the API Reference is the best place to look.

You can also check out src/tests/schema.rs to see a complex schema including polymorphism with traits and interfaces. For an example of web framework integration, see the rocket and iron examples folders.

Features

Juniper supports the full GraphQL query language according to the specification, including interfaces, unions, schema introspection, and validations. It does not, however, support the schema language.

As an exception to other GraphQL libraries for other languages, Juniper builds non-null types by default. A field of type Vec<Episode> will be converted into [Episode!]!. The corresponding Rust type for e.g. [Episode] would be Option<Vec<Option<Episode>>>.

Integrations

Data types

Juniper has automatic integration with some very common Rust crates to make building schemas a breeze. The types from these crates will be usable in your Schemas automatically.

Web Frameworks

rocket
iron

API Stability

Juniper has not reached 1.0 yet, thus some API instability should be expected.

Re-exports

pub use crate::executor::Context;

pub use crate::executor::ExecutionError;

pub use crate::executor::ExecutionResult;

pub use crate::executor::Executor;

pub use crate::executor::FieldError;

pub use crate::executor::FieldResult;

pub use crate::executor::FromContext;

pub use crate::executor::IntoFieldError;

pub use crate::executor::IntoResolvable;

pub use crate::executor::Registry;

pub use crate::executor::ValuesStream;

pub use crate::executor::Variables;

Modules

executor

Resolve the document to values

http

Utilities for building HTTP endpoints in a library-agnostic manner

integrations

Provides GraphQLType implementations for some external types

marker

Marker traits for GraphQL types.

Macros

graphql_value

Construct JSON-like values by using JSON syntax

Structs

Arguments

Field argument container

EmptyMutation

Utility type to define read-only schemas

EmptySubscription

Utillity type to define read-only schemas

ExecutionOutput

Represents the result of executing a GraphQL operation (after parsing and validating has been done).

ID

An ID as defined by the GraphQL specification

LookAheadArgument

An argument passed into the query

LookAheadSelection

A selection performed by a query

Object

A Object value

Operation

OwnedExecutor

Executor owning all its variables. Can be used after Executor was destroyed.

RootNode

Root query node of a schema

RuleError

Query validation error

SchemaType

Metadata for a schema

Spanning

Data structure used to wrap items with start and end markers in the input source

Enums

Applies

An enum that describes if a field is available in all types of the interface or only in a certain subtype

DefaultScalarValue

The default scalar value representation in juniper

GraphQLError

An error that prevented query execution

InputValue

A JSON-like value that can be passed into the query execution, either out-of-band, or in-band as default variable values. These are not constant and might contain variables.

IntrospectionFormat

The desired GraphQL introspection format for the canonical query (https://github.com/graphql/graphql-js/blob/8c96dc8276f2de27b8af9ffbd71a4597d483523f/src/utilities/introspectionQuery.js#L21)

LookAheadValue

A JSON-like value that can is used as argument in the query execution

Nullable

Nullable can be used in situations where you need to distinguish between an implicitly and explicitly null input value.

OperationType

ParseError

Error while parsing a GraphQL query

Selection

Entry in a GraphQL selection set

Type

A type literal in the syntax tree

TypeKind

GraphQL type kind

Value

Serializable value returned from query and field execution.

Traits

AsDynGraphQLValue

Conversion of a GraphQLValue to its trait object.

ExtractTypeFromStream

This trait is used in juniper::graphql_subscription macro to get stream’s item type that implements GraphQLValue from type alias provided by user.

FromInputValue

Parse an unstructured input value into a Rust data type.

GraphQLInterface

Maker trait for GraphQL interfaces.

GraphQLSubscriptionType

Extension of GraphQLType trait with asynchronous subscription execution logic.

GraphQLSubscriptionValue

Extension of GraphQLValue trait with asynchronous subscription execution logic. It should be used with GraphQLValue in order to implement subscription resolvers on GraphQL objects.

GraphQLType

Primary trait used to expose Rust types in a GraphQL schema.

GraphQLTypeAsync

Extension of GraphQLType trait with asynchronous queries/mutations resolvers.

GraphQLUnion

Maker trait for GraphQL unions.

GraphQLValue

Primary trait used to resolve GraphQL values.

GraphQLValueAsync

Extension of GraphQLValue trait with asynchronous queries/mutations resolvers.

IntoFieldResult

Trait for wrapping [Stream] into Ok if it’s not Result.