How do I create a required "BelongsTo" association using Sequelize?

Question

Using Sequelize, I've created two models: User and Login.

Users can have more than one Login, but a login must have exactly one user.

How do I specify in the login model that a user must exist before a save can occur?

Current Code

var User = sequelize.define('User', {});
var Login = sequelize.define('Login', {});
Login.belongsTo(User, { foreignKey: 'userId' });

This setup would still allow a login to save before a user has been specified. For instance Login.build().save(); would execute without any validation error.

Answer 1

The answer lies in the foreignKey attribute, which actually takes in a full blown column object.

Specifically, instead if 'userId' it should be:

Login.belongsTo(User, {
  foreignKey: {
    field: 'userId',
    allowNull: false
  },
  onDelete: 'cascade'
});

Notice that onDelete has to be updated as well, because the default value for onDelete is SET NULL which may generate errors at the database level due to the rule conflict.

Thank you to the friendly folks in #sequelizejs on Freenode!