graphql_example.js

import {
  graphql,
  GraphQLSchema,
  GraphQLObjectType,
  GraphQLNonNull,
  GraphQLList,
  GraphQLString,
} from 'graphql';

// data
var toshihiro = {
  name: 'Toshihiro Suzuki',
  friends: ['2', '3'],
};

var ichiro = {
  name: 'Ichiro Fukuda',
  friends: ['1'],
};

var ryota = {
  name: 'Ryota Nishio',
  friends: ['1'],
};

var users = {
  1: toshihiro,
  2: ichiro,
  3: ryota,
};

var loginUser = toshihiro;

function getFriends(user) {
  return user.friends.map(id => users[id]);
}

// schema

// type User {
//   name: String
//   friends: [User]
// }
var userType = new GraphQLObjectType({
  name: 'User',
  fields: () => ({
    name: {
      type: GraphQLString,
    },
    friends: {
      type: new GraphQLList(userType),
      resolve: (user) => getFriends(user),
    },
  }),
});

// type Query {
//   me: User
//   user(id: Int): User
// }
var queryType = new GraphQLObjectType({
  name: 'Query',
  fields: () => ({
    me: {
      type: userType,
      resolve: () => loginUser,
    },
    user: {
      type: userType,
      args: {
        id: {
          name: 'id',
          type: new GraphQLNonNull(GraphQLString),
        }
      },
      resolve: (root, {id}) => users[id],
    },
  }),
});

var schema = new GraphQLSchema({
  query: queryType,
});

// query
var query = '{ me { name } }';

graphql(schema, query).then(result => {
  // handle the result
  // {
  //    "me": "Toshihiro Suzuki"
  // }
});

var query = '{ me { name friends { name } } }';

graphql(schema, query).then(result => {
  // handle the result
  // {
  //    "me": "Toshihiro Suzuki",
  //    "friends": [
  //      {
  //        "name": "Ichiro Fukuda"
  //      },
  //      {
  //        "name": "Ryota Nishio"
  //      }
  //    ]
  // }
});

var query = '{ user(id: "2") { name friends { name } } }'

graphql(schema, query).then(result => {
  // handle the result
  // {
  //    "user": "Ichiro Fukuda",
  //    "friends": [
  //      {
  //        "name": "Toshihiro Suzuki"
  //      }
  //    ]
  // }
});