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title layout updated category
GraphQL
2017/sheet
2017-09-23
Databases

Intro

Queries

{: .-three-column}

Basic query

{ status }

{ status: 'available' }

{: .-setup}

Nesting

{ hero { name height } }

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

{: .-setup}

Lists

{ friends { name } }

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

{: .-setup}

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" } }

{: .-setup}

Aliases

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

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

{: .-setup}

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

{: .-three-column}

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!
}

{: data-line="1,2,3,4"}

Unions

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

union Result = Artist | Album

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

{: data-line="4"}

References

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