OpenCart从控制器传递到视图

Question

New to OpenCart and am having issues. I'm Trying to get the sum of a column from a table and display it on a page. I've tried a few iterations of the following but always get an undefined variable error. I've been stuck on this for a while and am not sure what Im doing wrong.

my model:

 public function getSum() {
        $amount_total = $this->db->query("SELECT FROM oct_donate SUM(amount) as amount_sum");
        $sums = $amount_total->row["amount_sum"];
        return $sums; 
        }

my controller:

public function sum() {

        $data['total_sum']=$this->load->model('revenue/order')->getSum();      

    }

view: <?php echo $total_sum; ?> <?php echo $total_sum; ?>

Answer 1

The problem is in your controller code. You have to load the model first and then call its method. Update the code.

public function sum() {
  $this->load->model('revenue/order')
  $data['total_sum']=$this->model_revenue_order->getSum();
}

Also your query is not correct. I think you missed to select columns. It should be

$this->db->query("SELECT SUM(amount) as amount_sum FROM oct_donate");