How does map work with a Backbone collection?

Question

Goal: I am trying to create a case insensitive search that goes through my collection and tries to match the user query against model's name attribute. Right now if I want to find a specific model, the search query must be exact.

It seems there is no easy way to do something so simple in Backbone, not out of the box. The function map came to mind. What if I could go through the entire collection and change model's name attribute to lower case, then change user query to lower case as well and voila!

But the problem is I have no idea how to use Backbone Collection and map function. There is no documentation on map in Backbone docs, other than a link that leads you to underscore documentation with a super primitive example code using an array of three numbers.

This does not work...why?

this.collection.map(function(model) {
  return model.get('name').toLowerCase();
});

Answer 1

Actually, all of underscore's collection methods are proxied on Backbone.Collection objects. when you do a collection.map(... it returns an array of objects returned by the mapped function. The solution presented by raina77ow does not work since a Backbone.Collection is not an array and assigning the result of the map to this.collection will destroy the collection itself.

If you want to filter a collection, I would recommend using the filter method. ( I assume you are working from a Backbone.View:

var filter = this.$('#search-field').val(),
    filteredModels = this.collection.filter( function( model ) {
  return model.get('name').toLowerCase() === filter;
};
this.collection.reset( filteredModels );

Note that any of underscore's proxied methods on collections will return an array of models. If you then want to use them, you can reset the collection with these models or, equivalently, set the collection's models attribute to the filtered results: this.collection.models = filteredModels. The first form has the advantage of triggering a reset event on the collection to which you can listen to and, for example re-render your view.