Sometimes, you face problem you can't get post data using $this->input->post(), when you fire $http.post() using AngularJS or Jquery. I also face this issue, i can't receive post value when i fire $http.post in AngularJS, But i found how to receive post data or json data in Codeigniter controller. in following example through you can solve your problem:

public function store()
{
	$this->load->database();
	$_POST = json_decode(file_get_contents('php://input'), true);
	$posts = $this->input->post();
	$this->db->insert('posts', $posts);
}