Cart in the opencart

Cart:
Functions that are in the cart library of opencart are:
$this->cart->getProducts():
This is the line which is used for getting the products that are in the cart.
public function getProducts() {
$product_data = array();

foreach ($this->session->data['cart'] as $key => $value) {
$array = explode(':', $key);
$product_id = $array[0];
$quantity = $value;
$stock = TRUE;

if (isset($array[1])) {
$options = explode('.', $array[1]);
} else {
$options = array();
}

$product_query = $this->db->query("SELECT *, wcd.unit AS weight_class, mcd.unit AS length_class FROM " . DB_PREFIX . "product p LEFT JOIN " . DB_PREFIX . "product_description pd ON (p.product_id = pd.product_id) LEFT JOIN " . DB_PREFIX . "weight_class wc ON (p.weight_class_id = wc.weight_class_id) LEFT JOIN " . DB_PREFIX . "weight_class_description wcd ON (wc.weight_class_id = wcd.weight_class_id) LEFT JOIN " . DB_PREFIX . "length_class mc ON (p.length_class_id = mc.length_class_id) LEFT JOIN " . DB_PREFIX . "length_class_description mcd ON (mc.length_class_id = mcd.length_class_id) WHERE p.product_id = '" . (int)$product_id . "' AND pd.language_id = '" . (int)$this->config->get('config_language_id') . "' AND wcd.language_id = '" . (int)$this->config->get('config_language_id') . "' AND p.date_available <= NOW() AND p.status = '1'"); if ($product_query->num_rows) {
$option_price = 0;

$option_data = array();

foreach ($options as $product_option_value_id) {
$option_value_query = $this->db->query("SELECT * FROM " . DB_PREFIX . "product_option_value pov LEFT JOIN " . DB_PREFIX . "product_option_value_description povd ON (pov.product_option_value_id = povd.product_option_value_id) WHERE pov.product_option_value_id = '" . (int)$product_option_value_id . "' AND pov.product_id = '" . (int)$product_id . "' AND povd.language_id = '" . (int)$this->config->get('config_language_id') . "' ORDER BY pov.sort_order");

if ($option_value_query->num_rows) {
$option_query = $this->db->query("SELECT pod.name FROM " . DB_PREFIX . "product_option po LEFT JOIN " . DB_PREFIX . "product_option_description pod ON (po.product_option_id = pod.product_option_id) WHERE po.product_option_id = '" . (int)$option_value_query->row['product_option_id'] . "' AND po.product_id = '" . (int)$product_id . "' AND pod.language_id = '" . (int)$this->config->get('config_language_id') . "' ORDER BY po.sort_order");

if ($option_value_query->row['prefix'] == '+') {
$option_price = $option_price + $option_value_query->row['price'];
} elseif ($option_value_query->row['prefix'] == '-') {
$option_price = $option_price - $option_value_query->row['price'];
}

$option_data[] = array(
'product_option_value_id' => $product_option_value_id,
'name' => $option_query->row['name'],
'value' => $option_value_query->row['name'],
'prefix' => $option_value_query->row['prefix'],
'price' => $option_value_query->row['price']
);

if ($option_value_query->row['subtract'] && (!$option_value_query->row['quantity'] || ($option_value_query->row['quantity'] < $quantity))) { $stock = FALSE; } } } if ($this->customer->isLogged()) {
$customer_group_id = $this->customer->getCustomerGroupId();
} else {
$customer_group_id = $this->config->get('config_customer_group_id');
}

$discount_quantity = 0;
foreach ($this->session->data['cart'] as $k => $v) {
$array2 = explode(':', $k);
if ($array2[0] == $product_id) {
$discount_quantity += $v;
}
}

$product_discount_query = $this->db->query("SELECT price FROM " . DB_PREFIX . "product_discount WHERE product_id = '" . (int)$product_id . "' AND customer_group_id = '" . (int)$customer_group_id . "' AND quantity <= '" . (int)$discount_quantity . "' AND ((date_start = '0000-00-00' OR date_start < NOW()) AND (date_end = '0000-00-00' OR date_end > NOW())) ORDER BY quantity DESC, priority ASC, price ASC LIMIT 1");

if ($product_discount_query->num_rows) {
$price = $product_discount_query->row['price'];
} else {
$product_special_query = $this->db->query("SELECT price FROM " . DB_PREFIX . "product_special WHERE product_id = '" . (int)$product_id . "' AND customer_group_id = '" . (int)$customer_group_id . "' AND ((date_start = '0000-00-00' OR date_start < NOW()) AND (date_end = '0000-00-00' OR date_end > NOW())) ORDER BY priority ASC, price ASC LIMIT 1");

if ($product_special_query->num_rows) {
$price = $product_special_query->row['price'];
} else {
$price = $product_query->row['price'];
}
}

$download_data = array();

$download_query = $this->db->query("SELECT * FROM " . DB_PREFIX . "product_to_download p2d LEFT JOIN " . DB_PREFIX . "download d ON (p2d.download_id = d.download_id) LEFT JOIN " . DB_PREFIX . "download_description dd ON (d.download_id = dd.download_id) WHERE p2d.product_id = '" . (int)$product_id . "' AND dd.language_id = '" . (int)$this->config->get('config_language_id') . "'");

foreach ($download_query->rows as $download) {
$download_data[] = array(
'download_id' => $download['download_id'],
'name' => $download['name'],
'filename' => $download['filename'],
'mask' => $download['mask'],
'remaining' => $download['remaining']
);
}

if (!$product_query->row['quantity'] || ($product_query->row['quantity'] < $quantity)) { $stock = FALSE; } $product_data[$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' => $stock,
'price' => ($price + $option_price),
'total' => ($price + $option_price) * $quantity,
'tax_class_id' => $product_query->row['tax_class_id'],
'weight' => $product_query->row['weight'],
'weight_class' => $product_query->row['weight_class'],
'length' => $product_query->row['length'],
'width' => $product_query->row['width'],
'height' => $product_query->row['height'],
'length_class' => $product_query->row['length_class']
);
} else {
$this->remove($key);
}
}

return $product_data;
}
$this->cart->add($product_id, $qty = 1, $options = array()):
By this we are able to add product in the cart. Actually in the cart the products’ Id and the requested quantity and the options of the product is stored in the array.
public function add($product_id, $qty = 1, $options = array()) {
if (!$options) {
$key = $product_id;
} else {
$key = $product_id . ':' . implode('.', $options);
}

if ((int)$qty && ((int)$qty > 0)) {
if (!isset($this->session->data['cart'][$key])) {
$this->session->data['cart'][$key] = (int)$qty;
} else {
$this->session->data['cart'][$key] += (int)$qty;
}
}
$this->setMinQty();
}
$this->cart->update($key, $qty):
By this we update the product quantity in the cart. So the parameters that we need are the product id and the quantity amount.
public function update($key, $qty) {
if ((int)$qty && ((int)$qty > 0)) {
$this->session->data['cart'][$key] = (int)$qty;
} else {
$this->remove($key);
}
$this->setMinQty();
}
$this->cart->remove($key):
Remove the product from the cart and the parameter that it take is the product id and the product with the product is deleted from the cart.
public function remove($key) {
if (isset($this->session->data['cart'][$key])) {
unset($this->session->data['cart'][$key]);
}
}
$this->cart->clear():
Clear all the product from the cart or cart is empty
public function clear() {
$this->session->data['cart'] = array();
}
$this->cart->getWeight():
This function returns the weight of the cart means the total weight of the products in the cart.
public function getWeight() {
$weight = 0;

foreach ($this->getProducts() as $product) {
if ($product['shipping']) {
$weight += $this->weight->convert($product['weight'] * $product['quantity'], $product['weight_class'], $this->config->get('config_weight_class'));
}
}
return $weight;
}
$this->cart->setMinQty():
public function setMinQty() {
foreach ($this->getProducts() as $product) {
if ($product['quantity'] < $product['minimum']) { $this->session->data['cart'][$product['key']] = $product['minimum'];
}
}
}
$this->cart->getSubTotal():
Returns the sub total of the cart.
public function getSubTotal() {
$total = 0;
foreach ($this->getProducts() as $product) {
$total += $product['total'];
}
return $total;
}
$this->cart->getTaxes():
Returns the total taxes that is applicable to the cart’s products
public function getTaxes() {
$taxes = array();

foreach ($this->getProducts() as $product) {
if ($product['tax_class_id']) {
if (!isset($taxes[$product['tax_class_id']])) {
$taxes[$product['tax_class_id']] = $product['total'] / 100 * $this->tax->getRate($product['tax_class_id']);
} else {
$taxes[$product['tax_class_id']] += $product['total'] / 100 * $this->tax->getRate($product['tax_class_id']);
}
}
}

return $taxes;
}
$this->cart->getTotal():
Returns the total cost of the cart.
public function getTotal() {
$total = 0;
foreach ($this->getProducts() as $product) {
$total += $this->tax->calculate($product['total'], $product['tax_class_id'], $this->config->get('config_tax'));
}
return $total;
}
$this->cart->countProducts():
Returns the total number of the product in the cart
public function countProducts() {
return array_sum($this->session->data['cart']);
}
$this->cart->hasProducts():
Checks whether there is product in the cart or not.
public function hasProducts() {
return count($this->session->data['cart']);
}
$this->cart->hasStock():
Checks whether there is stock for the product in the cart or not.
public function hasStock() {
$stock = TRUE;

foreach ($this->getProducts() as $product) {
if (!$product['stock']) {
$stock = FALSE;
}
}

return $stock;
}
$this->cart->hasShipping():
Checks whether the cart contains the shipping address or not.
public function hasShipping() {
$shipping = FALSE;

foreach ($this->getProducts() as $product) {
if ($product['shipping']) {
$shipping = TRUE;

break;
}
}
return $shipping;
}
$this->cart->hasDownload():
This is useful for the downloadable products and checks whether it is downloadable or custom product
public function hasDownload() {
$download = FALSE;
foreach ($this->getProducts() as $product) {
if ($product['download']) {
$download = TRUE;
break;
}
}
return $download;
}

description of the function in opencart,uses of the cart function, ways to make the cart functions work properly in the opencart, cart functions desciption