sequelize_multiple_associate.js

const sequelize = require('sequelize')

const db = new sequelize('test', 'test', '', {
  dialect: 'postgres',
  host: '127.0.0.1',
  port: 5432,
})

const Foo = db.define('foo')
const Bar = db.define('bar')

Foo.belongsTo(Bar, {as: 'foo'})

// as 'foo' multi times will throw exception in sequelize@4
// You have used the alias foo in two separate associations. Aliased associations must have unique aliases.
// sequelize@3 will work as normal
Foo.belongsTo(Bar, {as: 'foo'})

// use a new alias name will fix this issue
Foo.belongsTo(Bar, {as: 'another'})