javascript - Inherit attributes and lifecycle functions of Sails.js models

Question

I want to create a custom set of attributes and lifecycle methods that are shared between all my Sails.js models.

Sails.js automatically creates and registers the model objects by calling the Waterline.Collection.extend() method and providing the model definition found inside the /api/models directory.

What would be the best way to extend my model definition from a parent? I already tried using _.extend(sails.config.model.parentModel, childModel) but sadly the sails object is not exposed globally (since this is done after loading the orm hook). I could also simply require() the base model in all my models and extend it.

What would be a clean approach that goes well with Sails?

Answer 1

Using config/models.js to provide global defaults for models is perfectly valid. Concerning overriding instance and class methods there is nothing fancy to watch out for according to my tests. Defining a property / method present in sails.config.models in a model definition will override it for this model, leaving it undefined won't.

Definitions:

// config/models.js
module.exports.models = {
  attributes: {
    // base model instanceMethod
    toJSON: function() {
      console.log('base.toJSON');
      return this.toObject();
    }
  },

  // base model classMethod
  test: function() {
    console.log('base.test');
  }
};


// api/models/first.js
module.exports = {
  attributes: {

  },

  // Overriding classMethods and lifecycle callbacks
  test: function() {
    console.log('first.test');
  }
};

// api/models/second.js
module.exports = {
  attributes: {
    // Overriding instance methods and attributes
    toJSON: function() {
      console.log('second.toJSON');
      return this.toObject();
    }
  },
}

Tests

> sails.models.first.test();
>'first.test' // sails.config.models.test overridden

> sails.models.first.findOne(1).exec(err,res){ res.toJSON();  });
> 'base.toJSON' // sails.config.models.attributes.toJSON not overridden

> sails.models.second.test();
> 'base.test'; // sails.config.models.test not overridden

> sails.models.second.findOne(1).exec(err,res) { res.toJSON(); });
> 'second.toJSON' // sails.config.models.attributes.toJSON overridden