Collections

In notebook:
FrontEndMasters BackboneJS
Created at:
2016-06-10
Updated:
2016-06-10
Tags:
libraries JavaScript
Collections are ordered set of models

Hello world:
  var Library = Backbone.Collection.extend({
    model: Song
});

var songCollection = new Library([
    {
        artist: "Death Cab for Cutie",
        title: "Codes & Keys"
    },
        {
        artist: "Noisettes",
        title: "Atticues"
    }
]);

songCollection.models.length; // 2
You can add your custom model, if you don't Backbone will just use a generic Backbone model.

In most cases you don't need to override the model on the collection. you can pass a single model or an array.

Add models to the collection:
  // A
songColleciotn.add({
    artist: "Noisettes",
    title: "Cheap Kicks"
});

// B
songCollection.create({
    artist: "The Damned",
    title: "Jet Boy Jet Girl"
});
​.create​ will also post to the restful service.

Polymorphic Models

The ​model​ property can be a function and follow multiple paths:
  Backbone.Collection.extend{({
    model: function() {
        if(condition){
            return BookModel;
        } else {
            return NovellaModel;
        }
    }
})
No typical use case.

The model will also have ​collection​ property that points to the instance of the collection. So you can access the parent collection. caveat: models can belong to multiple collections, but only the first one is lister in the ​collection​ property.

​remove()​

Many of the methods are the same as in underscore (all of them that exist in underscore on arrays).
​var lowBitrateSongs = songCollection.where({quality:poor})​
​songCollection.remove(lowBitrateSongs)​

​.where​ is an alias to ​filter​

Collection are ordered in the order they are added

But you can do ​library(song_two, {at: 0});​ which will add at the beginning

You can also do ​library.pluck("title")​ which will give back an array of song titles (​["song one", "song two", "song three"]​