GraphQL formatting: syntax and tools

GraphQL is a query language for APIs, developed by Facebook in 2015 and released as an open standard. Unlike REST, GraphQL provides a single access point and lets the client specify exactly which data it needs.

Basic GraphQL syntax

Query — retrieving data

query GetUser($id: ID!) {
  user(id: $id) {
    id
    name
    email
    posts {
      title
      createdAt
    }
  }
}

Mutation — modifying data

mutation CreatePost($input: PostInput!) {
  createPost(input: $input) {
    id
    title
    author {
      name
    }
  }
}

Fragments — reusable blocks

fragment UserFields on User {
  id
  name
  avatarUrl
}

query {
  me { ...UserFields }
  user(id: "1") { ...UserFields }
}

GraphQL vs. REST

Why format GraphQL queries

Readability: a minified query on a single line is difficult to debug. Indentation makes field nesting visible.

Minification: for production requests, extra spaces and line breaks are removed to reduce the request body size.

Minification example:

# Исходный запрос (65 символов с пробелами)
query { user(id: "1") { name email } }

# Минифицированный (36 символов)
query{user(id:"1"){name email}}

Type system and schema

GraphQL is a strongly typed language. The schema defines the data structure:

type User {
  id: ID!
  name: String!
  email: String
  age: Int
  posts: [Post!]!
}

type Query {
  user(id: ID!): User
  users: [User!]!
}

type Mutation {
  createUser(name: String!, email: String!): User!
}

! means a non-nullable field. [Post!]! is a non-nullable list of non-nullable elements.

To work with GraphQL JSON responses, use the JSON formatter and JSONPath to extract data.

Tool on reChecker

The GraphQL formatter on reChecker formats queries with proper indentation for readability or minifies them for sending. It highlights syntax errors before execution.

Open the tool on reChecker →