A proposal for API design of Hooks in Sequelize

sequelize_hooks_api_proposal.js

// The primary reason why hooks is not plug and play is the need for asynchronicity 
// This is my proposal on how we might implement this
// It's written as kind of pseudo code with knowledge of sequelize internals

// To keep the method signatures easier to understand, i propose that all hook callbacks are called with the current model as context (if available), parameters are arguments with the final arguments being a next callback
// The hooks would then be able to be chained via the next callbacks, ala middleware

var User = sequelize.define('User', {
  // fields
}, {
  // instanceMethods, etc
  hooks: {
    beforeCreate: [
      function(values, next) {
        // Do stuff before creating
      },
    ],
    afterCreate: function(values, next) {
      // Do stuff before creating
    }
  }
});

User.hook('beforeUpdate', function (values, next) {
  // Do stuff before updating
});
User.hook('beforeDestroy', function (next) {
  // Do stuff before destroying
});
User.hook('beforeDestroy', function (next) {
  // Do other stuff before destroying
});

// An indefinite amount of hooks for the same hook should be able to be defined.


// Internally:
DAOFactory.create = function(values) {
  var emitter = new CustomEventEmitter();

  DAOFactory.evaulateHooks('beforeCreate', values, function () {
    var model = this.build(values);

    model.save().proxy(emitter);
  });
  
  return emitter;
}