Intro

Queries

Basic query

{ status }

↓

{ status: 'available' }

Nesting

{ hero { name height } }

↓

{ hero:
    { name: "Luke Skywalker",
      height: 1.74 } }

Lists

{ friends { name } }

↓

{ friends:
    [ { name: "Luke Skywalker" },
      { name: "Han Solo" },
      { name: "R2D2" } ] }

GraphQL queries look the same for both single items or lists of items.

Lookups

{
  hero(id: "1000") { id name }
}

↓

{ hero:
    { id: "1000",
    { name: "Luke Skywalker" } }

Aliases

{
  luke: hero(id: "1000") { name }
  han: hero(id: "1001") { name }
}

↓

{ luke:
    { name: "Luke Skywalker" },
    han:
    { name: "Han Solo" } }

Operation names and variables

Query

query FindHero($id: String!) {
  hero(id: $id) { name }
}

Just to make things less ambiguous. Also, to use variables, you need an operation name.

Variables

{ id: '1000' }

Mutations

Query

{ createReview($review) { id } }

Variables

{ review: { stars: 5 } }

↓

{ createReview: { id: 5291 } }

Mutations are just fields that do something when queried.

Multiple types

{
  search(q: "john") {
    id
    ... on User { name }
    ... on Comment { body author { name } }
  }
}

Great for searching.

Over HTTP

GET

fetch('http://myapi/graphql?query={ me { name } }')

POST

fetch('http://myapi/graphql', {
  body: JSON.stringify({
    query: '...',
    operationName: '...',
    variables: { ... }
  })
})

Schema

Basic schemas

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

type User {
  id: ID!
  name: String
}

See: sogko/graphql-shorthand-notation-cheat-sheet

Built in types

Scalar types

Int Integer
Float Float
String String
Boolean Boolean
ID ID

Type definitions

scalar Scalar type
type Object type
interface Interface type
union Union type
enum Enumerable type
input Input object type

Type modifiers

String Nullable string
String! Required string
[String] List of strings
[String]! Required list of strings
[String!]! Required list of required strings

Mutations

type Mutation {
  users(params: ListUsersInput) [User]!
}

Interfaces

interface Entity {
  id: ID!
}

type User implements Entity {
  id: ID!
  name: String
}

Enums

enum DIRECTION {
  LEFT
  RIGHT
}

type Root {
  direction: DIRECTION!
}

Unions

type Artist { ··· }
type Album { ··· }

union Result = Artist | Album

type Query {
  search(q: String) [Result]
}

References