What

Queries

type Person {
  id: ID!
  name: String!
  age: Int!
  friends: [Person]!
}

type Query {
  allPersons(last: Int): [Person]!
}

query AllPersonsQuery {
  allPersons {
    name
  }
}

{
  "allPersons": [
    { "name": "Alice" },
    { "name": "Bob" },
    { "name": "Cathy" }
  ]
}

More on Queries

query AllPersonsQuery($first: Int!) {
  allPersons(first: $first) {
    name
    friends {
      name
    }
  }
}

{
  "allPersons": [
    {
      "name": "Alice",
      "friends": [
        { "name": "Bob" },
        { "name": "Cathy" }
      ]
    }
  ]
}

type Mutation {
  createPerson(input: PersonInput!): Person
}

mutation CreatePerson ($input: PersonInput!) {
  createPerson(input: $input) {
    name
    age
  }
}

{
  "allPersons": {
    "name": "Alice",
    "age": 36
  }
}

type Subscription {
  newPerson: Person!
}

subscription {
  newPerson {
    name
    age
  }
}

{
  "newPerson": {
    "name": "Jane",
    "age": 23
  }
}

Demo

https://graphql.org/swapi-graphql/​

Why

How

Server (Ruby)

#Gemfile
gem 'graphql'
gem 'graphiql-rails', group: :development

#Gemfile
gem 'graphql'
gem 'graphiql-rails', group: :development

# Install
bundle

# Setup with Rails:
rails generate graphql:install

# app/graphql/types/user_type.rb
Types::UserType = GraphQL::ObjectType.define do
  name "User"
  field :id, !types.ID
  field :name, !types.String
  field :avatar, Types::PhotoType
end

# app/controllers/graphql_controller.rb
result = MySchema.execute(
  params[:query],
  variables: params[:variables],
  context: { current_user: current_user },
)
render json: result

Show me the code!

Client (Javascript)