Question

Hi i have a json file that looks like this:

{
"links_1": [
    {
        "navn": "somename",
        "link": "http://www.domane.com"
    },
    {
        "navn": "somename",
        "link": "http://www.domane.com"
    },
    {
        "navn": "somename",
        "link": "http://www.domane.com"
    }
],
"links_2": [
    {
        "navn": "someothername",
        "link": "http://www.domane.com"
    },
    {
        "navn": "someothername",
        "link": "http://www.domane.com"
    },
    {
        "navn": "someothername",
        "link": "http://www.domane.com"
    }
]   
}

Then i have my Collection class.
Now i want to create a new collection that only contains the links_1 array from the json file.
And another new collection that contains the links_2 array from the json file.

How do i accomplish that?

var col = new Collection( Collection.prototype.parse = function(response){
return response.links_1;
}

So to illustrate further, i want my fetch to get specific json data objects.

var col = new Collection();
col.fetch(links_1);  //  here i only want to get links_1 json data

var col2 = new Collection();
col2.fetch(links_2); //  here i only want to get links_2 json data

any help would be great.

Answer 1

You’re on the right track with trying to override parse, you’re just doing it incorrectly. Try:

//define a collection class
var Link1Collection = Backbone.Collection.extend({
  parse:function(response) {
    return response.links_1
  }
});

//initialize a new instance of your collection class and fetch
var collection = new Link1Collection();
collection.fetch();

Edit: To select the field you want to extract on instance-to-instance basis, you can pass a custom option in the fetch options. The options are passed to parse:

//define a collection class
var LinkCollection = Backbone.Collection.extend({
  parse:function(response, options) {
    return options.parseField ? response[options.parseField] : response;
  }
});

//initialize a new instance of your collection class and fetch
var collection = new LinkCollection();
collection.fetch({parseField:'links_1'});