Sort by attributes Backbone.js

Question

I am trying to sort a collection and then update the view with the sorted collection. What I am trying is to sort a todo list by done or not done tasks. In my collection view I have this method:

    var AddTask = Backbone.View.extend({
    el: '#todos',

    initialize: function(){
        this.collection.fetch();
    },

    events: {
        'click #add': 'addTask',
        'click #filter_done': 'sort_done',
        'keypress #inputTask': 'updateOnEnter'
    },

    addTask: function(){

        var taskTitle = $('#inputTask'). val();
        $('#inputTask').val(""); //clear the input

        if($.trim(taskTitle) === ''){//check if the input has some text in it
            this.displayMessage("Todo's can not be empty");
        }else{
            var task = new Task( {title: taskTitle} ); // create the task model
            this.collection.create(task); //add the model to the collection         
        }
    },

    displayMessage: function(msg){
        $('#inputTask').focus().attr("placeholder", msg);
    },

    updateOnEnter: function(e){
        if(e.keyCode === 13){
            this.addTask();
        }
    },

    sort_done: function(){
        var done = this.collection.where({done: true});

    }

});

var addTask = new AddTask( {collection: tasks} ); 

My problem is that I don't know how to ask the view to render with the value returned by the sort_done method, and I also don't want to lose any information contained in the original collection.

Answer 1

One way would be to set a comparator on the collection, and then re-render your view on the collection's 'sort' event.

initialize: function() {
    // ...

    this.collection.on('sort', this.render, this);
},

sort_done: function() {
    this.collection.comparator = function(model) {
        return model.get('done') ? 1 : -1;
    };

    // This will trigger a 'sort' event on the collection
    this.collection.sort();
}

One disadvantage with this approach is that if the collection is shared between views, this will affect all views of the collection.