gistfile1.js

hall
  .create({
    foo: 'bar'
    bar: 'foo
  })
  .then(function(createdHall) {
    const hallId = createdHall.dataValues.id;
    return item.create({
      hallId: hallId,
      foo: 1
    });
  })
  .then(function(createdItem) {
     ...
  });
  .catch(function(error) {
     console.log('something went wrong with ONE of the promise callbacks (it could be any of them)');
  });