error creating in my controller

Code:

controller
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$this->load->model('user_model');          
       $data['appdetails_show'] = $this->user_model->getapp();

Model

Code:

public  function getapp(){
 $response = array();  

 $regno = $this->session->userdata('username');

 $this->db->select('*');
 $this->db->from('appdetpayment');
 $this->db->where('appdetpayment.regno',$regno);  
 $this->db->order_by('appdetpayment.appno');
 $query = $this->db->get();
 return $query->result_array();
 }