php - Codeigniter: How do I display the value returned by a model function on a view textbox during data entry -

this question based on following tables.

procedures - id | procedure_name |cost  visits - id | visit_date | patient_id | notes | staff_id  visits_procedures - id | visit_id | procedure_id | quantity  payments - id | visit_id | payment_date | amount | payment_method_id | transanction_id | payment_status_id 

the payments table records total amount paid during visit based on number of procedures performed. visits_procedures table tracks number of procedures performed during visit. trying populate amount textbox value returned get_visit_amount() function in model when creating new payment. getting error 'undefined variable: amount'. appreciate ideas on how make work. below code snippets.

payment model

public function get_visit_amount(){         $this->db->select_max('id');         $result= $this->db->get('visits')->row_array();         $answer = $result['id'];           $this->db->select('sum(procedures.cost * visits_procedures.quantity) amount, visits_procedures.visit_id');         $this->db->from('procedures');         $this->db->join('visits_procedures', 'visits_procedures.procedure_id = procedures.id', 'left');          $this->db->where('visits_procedures.visit_id', $answer);                $query = $this->db->get()->row_array();         return $query['amount'];     } 

payments controller

    public function create() {             if ($this->input->post('payment_method_id')) {                 $data['visit_id'] = $this->visit->get_latest_id();                 $data['payment_date'] = date('y-m-d h:i:s');                 $data['amount'] = $this->payment->get_visit_amount();                 $data['payment_method_id'] = $this->input->post('payment_method_id');                 $data['transaction_id'] = $this->input->post('transaction_id');                 $data['payment_status_id'] = $this->input->post('payment_status_id'); //set flash data             $this->session->set_flashdata('display_amount', $amount);             redirect('/admin/payments/create');                              $this->payment->insert($data);                             redirect('/admin/payments', 'refresh');             }      .     .// code load page     .      } 

payments_create view

<form class="form-horizontal" role="form" method="post" action="<?=base_url()?>admin/payments/create">         .         .//code         .      <div class="form-group">               <label class="col-md-3 col-xs-12 control-label">amount</label>               <div class="col-md-6 col-xs-12">                                                             <div class="input-group">                     <span class="input-group-addon"><span class="fa fa-pencil"></span></span>                     <input type="text" class="form-control" id="amount" name="amount" value="<?php echo $this->session->flashdata('display_amount'); ?>"/>                 </div>                                                           </div>         </div>         .         .//code         . </form> 

use flashdata store information.

$this->session->set_flashdata('item', 'value'); 

and retrieve in new page with

$this->session->flashdata('item'); 

wiki