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GraphQL

This quick reference cheat sheet provides a brief overview of GraphQL.

#Getting Started

#Overview

  • An alternative approach to RESTful APIs
  • GraphQL is a query language for APIs
  • Easily describe the shape of the GraphQL API using clear shared terms.
  • Clients issue queries/mutations to read and update data
  • GraphQL syntax can express complex entity relations
  • Libraries to implement GraphQL in different languages

GraphQL

#Schema
schema GraphQL schema definition
query Read and traverse data
mutation Modify data or trigger an action
subscription Run a query when an event occurs

#Built-in Scalar Types
Int Signed 32‐bit integer
Float Signed double-precision floating-point value
String UTF‐8 character sequence
Boolean true or false
ID A Unique identifier

#Type Definitions
scalar Scalar Type
type Object Type
interface Interface Type
union Union Type
enum Enum Type
input Input Object Type

#Type Modifiers
String Nullable String
String! Non-null String
[String] List of nullable Strings
[String]! Non-null list of nullable Strings
[String!]! Non-null list of non-null Strings

#Input Arguments

#Basic Input

type Query { users(limit: Int): [User] }

#Input with default value

type Query { users(limit: Int = 10): [User] }

#Input with multiple arguments

type Query { users(limit: Int, sort: String): [User] }

#Input with multiple arguments and default values

type Query { users(limit: Int = 10, sort: String): [User] } type Query { users(limit: Int, sort: String = "asc"): [User] } type Query { users(limit: Int = 10, sort: String = "asc"): [User] }

#Input Types

input ListUsersInput { limit: Int since_id: ID } 
type Mutation { users(params: ListUsersInput): [User]! }

#Custom Scalars

scalar Url type User { name: String homepage: Url }

#Interfaces

interface Foo { is_foo: Boolean } interface Goo { is_goo: Boolean } type Bar implements Foo { is_foo: Boolean is_bar: Boolean } type Baz implements Foo, Goo { is_foo: Boolean is_goo: Boolean is_baz: Boolean }

Object implementing one or more Interfaces

#Unions

type Foo { name: String } type Bar { is_bar: String } union SingleUnion = Foo union MultipleUnion = Foo | Bar type Root { single: SingleUnion multiple: MultipleUnion }

Union of one or more Objects

#Enums

enum USER_STATE { NOT_FOUND ACTIVE INACTIVE SUSPENDED } type Root { stateForUser(userID: ID!): USER_STATE! users(state: USER_STATE, limit: Int = 10): [User] }

#Also see