Question

Is there a way to easily clone Backbone Collection? I wonder why there is no build in method like for models. My problem is that I have a model holding a collection of childs. When I clone the model. I’ve still the collection of childs but only with their default values.

Answer 1

What’s your use case that you want to clone the collection?

There isn’t a built in clone function for a collection because you do not want to clone the models within the collection. Cloning a model would cause there to be two separate instances of the same model, and if you update one model, the other one won’t be updated.

If you want to create a new collection based upon a certain criteria, then you can use the collection’s filter method.

var freshmenModels = studentsCollection.filter(function(student) {
  return student.get('Year') === 'Freshman';
}

var freshmenCollection = new Backbone.Collection(freshmenModels);

To go ahead and clone the models in the collection, you can write the following code

var clonedCollection = new Backbone.Collection();
studentsCollection.each(function(studentModel) {
  clonedCollection.add(new Backbone.Model(studentModel.toJSON()));
});