function update_user_avatar()
 {
     $user_service = new User_service();
     $user_model = new User_model();
     $user_model->set_user_avatar($this->input->post('user_avatar', TRUE));
     $user_model->set_user_id($this->input->post('user_id', TRUE));
     $result = $user_service->update_user_avatar($user_model);
     //update session profile pic into new pic
     $this->session->set_userdata('USER_PROPIC', $this->input->post('user_avatar', TRUE));
     echo $result;
 }