Opencart price calculating, custom price calculation - php

Question

Im currently working on an opencart site. I have wrote custom price calculation php, depending which options are selected in order. This work fine, when options are select, radio ot checkboxes. But..
I have an option, where customer can input a number with text field. I use this number in price calculation, so depending on this value, opencart calculate the price. I send this number using SESSION to system/library/cart.php, where i use it for calculation. This works fine when customer order just once.
When customer already have a product in his cart, and want make another order, opencart will overwrite the session value, and this will recalculate price for the item already in cart.
is there any good method to store separately this session values?
Here is my modified system/library/cart.php:
if ($product_id == '65') {
$pqty = $_SESSION['pqty'];
$contents = file_get_contents("http://somepage.com/system/library/calculate.php?&qty=".$quantity."&pqty=".$pqty."&pnh=".$pnh."&czp=".$czp."&czt=".$czt."&bnd=".$bnd."&covcho=".$covcho."&covczp=".$covczp."&covczt=".$covczt."&lam=".$lam);
$contents = utf8_encode($contents);
$calcprice = json_decode($contents);
$this->data[$key] = array(
'key' => $key,
'product_id' => $product_query->row['product_id'],
'name' => $product_query->row['name'],
'model' => $product_query->row['model'],
'shipping' => $product_query->row['shipping'],
'image' => $product_query->row['image'],
'option' => $option_data,
'download' => $download_data,
'quantity' => $quantity,
'minimum' => $product_query->row['minimum'],
'subtract' => $product_query->row['subtract'],
'stock' => $stock,
'price' => $calcprice / quantity,
'total' => $calcprice,
'reward' => $reward * $quantity,
'points' => ($product_query->row['points'] ? ($product_query->row['points'] + $option_points) * $quantity : 0),
'tax_class_id' => $product_query->row['tax_class_id'],
'weight' => ($product_query->row['weight'] + $option_weight) * $quantity,
'weight_class_id' => $product_query->row['weight_class_id'],
'length' => $product_query->row['length'],
'width' => $product_query->row['width'],
'height' => $product_query->row['height'],
'length_class_id' => $product_query->row['length_class_id'],
'recurring' => $recurring
);

Answer 1

You created if ($product_id == '65') { in your system file. Which means you have to make code for every product id which is not feasible solution.
My suggestion is that you should create a session array like $this->session->data['custom_price']['your_product_id'] = value entered by customer. And using this you should calculate price for each item.

Answer 2

Is the issue for you that opencart is NOT creating a separate item in your cart and instead doubling it up on the same product? I was unclear if this was your exact problem, but if it is - you can enable duplicate products to be in your cart by modifying the following in your system/library/cart.php file:
Around line 290, you can change:
public function add($product_id, $quantity = 1, $option = array(), $recurring_id = 0) {
$query = $this->db->query("SELECT COUNT(*) AS total FROM " . DB_PREFIX . "cart WHERE api_id = '" . (isset($this->session->data['api_id']) ? (int)$this->session->data['api_id'] : 0) . "' AND customer_id = '" . (int)$this->customer->getId() . "' AND session_id = '" . $this->db->escape($this->session->getId()) . "' AND product_id = '" . (int)$product_id . "' AND recurring_id = '" . (int)$recurring_id . "' AND `option` = '" . $this->db->escape(json_encode($option)) . "'");
if (!$query->row['total']) {
$this->db->query("INSERT " . DB_PREFIX . "cart SET api_id = '" . (isset($this->session->data['api_id']) ? (int)$this->session->data['api_id'] : 0) . "', customer_id = '" . (int)$this->customer->getId() . "', session_id = '" . $this->db->escape($this->session->getId()) . "', product_id = '" . (int)$product_id . "', recurring_id = '" . (int)$recurring_id . "', `option` = '" . $this->db->escape(json_encode($option)) . "', quantity = '" . (int)$quantity . "', date_added = NOW()");
} else {
$this->db->query("UPDATE " . DB_PREFIX . "cart SET quantity = (quantity + " . (int)$quantity . ") WHERE api_id = '" . (isset($this->session->data['api_id']) ? (int)$this->session->data['api_id'] : 0) . "' AND customer_id = '" . (int)$this->customer->getId() . "' AND session_id = '" . $this->db->escape($this->session->getId()) . "' AND product_id = '" . (int)$product_id . "' AND recurring_id = '" . (int)$recurring_id . "' AND `option` = '" . $this->db->escape(json_encode($option)) . "'");
}
$this->data = array();
}
Change to:
// Modified to ENABLE duplicate product
public function add($product_id, $quantity = 1, $option = array(), $recurring_id = 0) {
$query = $this->db->query("INSERT " . DB_PREFIX . "cart SET api_id = '" . (isset($this->session->data['api_id']) ? (int)$this->session->data['api_id'] : 0) . "', customer_id = '" . (int)$this->customer->getId() . "', session_id = '" . $this->db->escape($this->session->getId()) . "', product_id = '" . (int)$product_id . "', recurring_id = '" . (int)$recurring_id . "', `option` = '" . $this->db->escape(json_encode($option)) . "', quantity = '" . (int)$quantity . "', date_added = NOW()");
$this->data = array();
}
// End
I use this modification because I have my own custom pricing, too, and it interfers with OpenCart's original code when it was trying to multiply the product in cart. As you can tell from the code, you're removing OC's query of product total and preventing it from over-riding / increasing the QTY of the same product when you add another instance of it into your cart. Instead, a separate instance/item will be added instead. It won't tamper with the functionality of a customer adding more than 1 QTY from the product page or increasing it in their view cart page, so that all stays the same still in case that's still needed. This just affects how products of the same product id are added into the cart.