Codeigniter RESTful API not returning JSON - php

Question

I have this application where I use Codeigniter as backend and Backbone as frontend. Now I use the RESTful API from https://github.com/philsturgeon/codeigniter-restserver. I want to fetch RSS feeds, so I created a RSS-model.php in application->models:
<?php
class Rss_model extends CI_Model
{
var $table_name = 'artist_news';
var $primary_key = 'news_id';
function get_all_rss_feeds()
{
$this->db->select($this->primary_key);
$this->db->from($this->table_name);
return $this->db->get();
}
}
?>
and then in application->controllers I created the folder api in which I created the file rss.php:
<?php
require(APPPATH.'libraries/REST_Controller.php');
class rss extends REST_Controller{
public function get_all_rss_feeds_get()
{
$this->load->database();
$this->load->model('rss_model');
$data = $this->rss_model->get_all_rss_feeds();
if($data) {
$this->response($data, 200);
} else {
$this->response(array('error' => 'Couldn\'t find any news!'), 404);
}
}
}
?>
So far so good, it returns an array of text with a lot of rss-feeds, but NOT in JSON format, which I need for my frontend.
Does anyone know what the issue is here?
Thanks in advance...
[EDIT]
My Backbone Code looks like this:
function (App, Backbone) {
var Rss = App.module();
Rss.View = Backbone.View.extend({
template: 'rss',
initialize: function() {
this.listenTo(this.collection, 'all', this.render)
},
serialize: function() {
return this.collection ? this.collection.toJSON() : [];
}
});
Rss.RssCollection = Backbone.Collection.extend({
url: function() {
return '/myproject/index.php/api/rss/get_all_rss_feeds/';
}
});
return Rss;
}

Answer 1

go to config/rest.php file and find this line :
$config['rest_default_format'] = 'xml';
change it to :
$config['rest_default_format'] = 'json';

Answer 2

I think you missed the result in return in the model please check below
function get_all_rss_feeds()
{
$this->db->select($this->primary_key);
$this->db->from($this->table_name);
return $this->db->get()->result();
}

Answer 3

If you are usign the Phil Sturgeon REST library you need to append the format type in the URL. Example:
http://example.com/books.json
http://example.com/books?format=json
If you want it in another format, let's say XML, you just need to pass the new format in the URI, doesn't need to change anything in your code. Example:
http://example.com/books.xml
http://example.com/books?format=xml
Further reading:
Content-Type Section - https://github.com/philsturgeon/codeigniter-restserver