Blank page after successful form submit - Codeigniter - php

Question

I am using below function to add an item to cart (which right now is an array, that will be stored in session later). Every thing is working fine only problem is that when i click "Add+" button, it stores all the values in the array but gives a blank page after.
My Controller
if($action == 'Add+') {
if($this->session->userdata('cart')== ''){
$image=$this->input->post('hidden_image');
$name= $this->input->post('hidden_name');
$price= $this->input->post('hidden_price');
$cat= $this->input->post('hidden_cat');
$id= $this->input->post('hidden_id');
$product = array("name"=>$name, "price"=>$price, "id"=>$id, "image" => $image,"cat"=>$cat);
$item= array("0"=>$product);
$this->session->set_userdata('cart',$item);
}
else{
$count= count($this->session->userdata('cart'));
$name= $this->input->post('hidden_name');
$price= $this->input->post('hidden_price');
$id= $this->input->post('hidden_id');
$image=$this->input->post('hidden_image');
$cat= $this->input->post('hidden_cat');
$product = array("name"=>$name, "price"=>$price, "id"=>$id, "image" => $image,"cat"=>$cat);
$item= array($count=>$product);
$data = $this->session->userdata('cart');
$_SESSION["cart"][$count] = $product;
}
}
if($action == 'View') {
$image=$this->input->post('hidden_image');
$name= $this->input->post('hidden_name');
$price= $this->input->post('hidden_price');
$id= $this->input->post('hidden_id');
$cat= $this->input->post('hidden_cat');
$product = array("name"=>$name, "price"=>$price, "id"=>$id, "image" => $image,"cat"=>$cat);
$this->load->view('product_head');
$this->load->view('header',$product);
$this->load->view('product',$product);
}
My View
<?php $data= array ('id'=>'productform');
echo form_open_multipart('loader/product',$data);
$data = array(
'type' => 'hidden',
'name' => 'hidden_cat',
'value' => $row->category);
$val = set_value('hidden_cat');
echo form_input($data, $val);
$data = array(
'type' => 'hidden',
'name' => 'hidden_name',
'value' => $row->name
);
$val = set_value('hidden_name');
echo form_input($data, $val);
$data = array(
'type' => 'hidden',
'name' => 'hidden_image',
'value' => $row->image
);
$val = set_value('hidden_image');
echo form_input($data, $val);
$data = array(
'type' => 'hidden',
'name' => 'hidden_id',
'value' => $row->id
);
$val = set_value('hidden_id');
echo form_input($data, $val);
$data = array(
'type' => 'hidden',
'name' => 'hidden_price',
'value' => $row->price
);
$val = set_value('hidden_price');
echo form_input($data, $val);
$data = array(
'name' => 'action',
'style' => ' background-color: #4CAF50; border: none;',
'value' => 'View'
);
echo form_submit($data);
$data = array(
'name' => 'action',
'style' => ' background-color: #4CAF50; border: none;',
'id' => 'addbtn'
);
echo form_submit($data);
echo form_close();
?>
what I want is that after successful form submit it stay on same page at same place because there are many pages that have these hidden forms for every product.