How to sort a collection in Backbone

0
votes

I want to sort my colection before I pass it to the template. I use in the render function of my view 

CollectionForTelplate : this.Collection

I do the fetch as

var self = this;
//fetch done here
if (Collection.length > 0) {
    _.each(Collection, function(Model) {
        JSON.stringify(Model);
    }, this);
};
self.Collection = Collection;
self.render;
  1. Is there any other way by means of which I can pass the collection to the template?
  2. How do you sort a collection based on a string field of the model, say Model.name ? I tried writing a comparator in the collection and a sort function the view but unfortunately; it doesnot work for me
2
backbone.js
I am sorry, but with the provided code snippets, not much help is possible. In your code, you are not passing any collection data to the template, your render function is not provided, what does your comparator look like, ........ Please provide the full code - schacki

2 Answers

1
votes

Implement your Collection's compatarator function, defined in the docs as

If you define a comparator, it will be used to maintain the collection in sorted order.

That way your collection will be automatically kept in a sorted order after adds, removals etc. You can implement it as sort

comparator: function(model1, model2) {
  if (model1 comes before model 2) {
    return -1;
  } else if (model1 is equal to model 2) {
    return 0;
  } else { // model1 comes after model 2
    return 1;
  }
}

or sortBy

comparator: function(model) {
  // Return some numeral or string attribute and it will be ordered by it
  // == smaller numbers come first / strings are sorted into alphabet order
  return model.get('someAttribute');
}

Hope this helps!

0
votes

Is there any other way by means of which I can pass the collection to the template?

Yes, collection's have a toJSON() method so you can simply do something like

render: function() {
  this._template({list: this.toJSON()}); //assuming your template is already compiled
  return this;
}

How do you sort a collection based on a string field of the model, say Model.name ? I tried writing a comparator in the collection and a sort function the view but unfortunately; it does not work for me

You can simply define the comparator function on the collection, and it should keep itself sorted, here's the example given in the docs

chapters.comparator = function(chapter) {
  return chapter.get("page");
};