Paste and go following URL, http://localhost:4000/play in your favorite web browser (Google Chrome recommended)

Type query like followings:

  query {
      getUserInfo(id: "neoroman") {
        id
        name
      }
  }

Meet first error like followings:

...
Error: Cannot return null for non-nullable field Query.getUserInfo.
...

Now you need models between GraphQL resolvers and MySQL.

Install sequelize-auto if you've not installed

$ brew sequelize-auto

Running sequelize-auto for generating GraphQL Schema with MySQL datebase root password = qwer1234.

Warning: using a password on the command line interface can be insecure.

$ sequelize-auto -c config/sequelize-auto.config.json -x qwer1234

Now you could find {TABLE_NAME}.js files in folder ./models !

Open graphql/resolvers.js

• Change codes commente No.1 and No.2 like followings:

  const resolvers = {
      Query: {
          getUserInfo: async (parent, args, context, info) => {
              try { 
                  // 1
                  let userId = { id: args.id }
                  const items = await AdminUser.findAll({ where: userId });
                  return items; 
              } 
              catch(err) {console.log(err);} 
          }
      },
      Mutation: {
          putUserInfo: async (parent, args, context, info) => {
              try {
                  // 2
                  const user = await AdminUser.findOne({ where: { id: args.id } });
                  if (user) {
                      if (args.password) {
                          user.set('password', args.password);
                          user.set('updateTime', (new Date()));
                      }
                      if (args.email) {
                          user.set('email', args.email);
                      }
                      return await user.save();
                  }
                  return new Error("putUserInfo: cannot find user:", args.id);
              }
              catch(err) {
                  console.log(err)
                  return new Error("putUserInfo", err);
              };
          }
      }
  }

  1. Query to AdminUser table where userId == args.id
  2. Update AdminUser table where userId == args.id

Click play button again, you could see the success result, Violla!