working demo of sequelize and graphql

index.js

const express = require('express');
const graphqlHTTP = require('express-graphql')
const app = express();
const PORT = process.env.PORT || 3000;
const bodyParser = require('body-parser');
const db = require('./models');
const User = db.User;
const pool = db.sequelize.connectionManager.pool;
// function, the actual executor of the schema
const { graphql } = require('graphql');

// app.use(bodyParser.urlencoded({ extended : false }));

// I used this route to get users in the DB
// app.post('/users', function (req, res) {
//   User.create({ username: req.body.username })
//     .then(function (user) {
//       res.json(user);
//     });
// });

// the schema to execute
const mySchema = require('./schema');

app.use('/graphql', (req, res) => {
  return graphqlHTTP({
    schema: mySchema,
    graphiql: true,
    context: { pool }, // available to all graphql resolve as the third argument
  })(req, res);
});

app.listen(PORT, function() {
  db.sequelize.sync();
});

schema.js

const {
  GraphQLSchema,
  GraphQLObjectType,
  GraphQLString,
  GraphQLInt,
  GraphQLList,
  GraphQLID,
  GraphQLNonNull
} = require('graphql');

const {resolver} = require('graphql-sequelize');
const User = require('./models').User;

let userType = new GraphQLObjectType({
  name: 'User',
  description: 'A user',
  fields: {
    id: {
      type: new GraphQLNonNull(GraphQLInt),
      description: 'The id of the user.',
    },
    username: {
      type: GraphQLString,
      description: 'The name of the user.',
    }
  }
});

let mySchema = new GraphQLSchema({
  query: new GraphQLObjectType({
    name: 'RootQueryType',
    fields: {
      user: {
        type: userType,
        // args will automatically be mapped to `where`
        args: {
          id: {
            description: 'id of the user',
            type: new GraphQLNonNull(GraphQLInt)
          }
        },
        resolve: resolver(User, {
          include: false // disable auto including of associations based on AST - default: true
        })
      }
    }
  })
});

module.exports = mySchema;

User.js

module.exports = function(sequelize, DataTypes) {
  var User = sequelize.define("User", {
    username: DataTypes.STRING
  });

  return User;
};