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title: GraphQL date: 2021-07-15 20:51:44 background: bg-[#cc44a2] tags: - query - API categories: - Programming intro: | This quick reference cheat sheet provides a brief overview of GraphQL. plugins: - copyCode

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 {.link-arrow}

Schema

Built-in Scalar Types

Type Definitions

Type Modifiers

Input Arguments {.row-span-2}

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

• GraphQL Schema Language Cheat Sheet (github.com)