Magento – How to exclude products being added to cart based on products attributes

addtocartcartevent-observermagento-1.9overrides

How can i set a condition, if pre-ordered products are purchased, no other products can be added to cart?

How can I set a condition like, if some of the "non-pre-order" products
is in the cart, not to be able to add a "pre-order" product. Visa verse if
my cart consists "pre-order" products, not allow "non-pre-order"
products to be added?

How can I do that?

Best Answer

You can use checkout_cart_product_add_after event to allow or disallow products being added ...

app/code/local/My/Module/etc/config.xml

<?xml version="1.0" encoding="UTF-8"?>
<config>
    <modules>
        <My_Module>
            <version>0.0.1</version>
        </My_Module>
    </modules>
    <global>
        <models>
            <my_module>
                <class>My_Module_Model</class>
            </my_module>
        </models>
        <events>
            <checkout_cart_product_add_after>
                <observers>
                    <test>
                        <class>my_module/observer</class>
                        <method>disallowProductAddToCart</method>
                    </test>
                </observers>
            </checkout_cart_product_add_after>
        </events>
        <!-- make custom attrribute available in quote item product -->
        <sales>
            <quote>
                <item>
                    <product_attributes>
                        <preorder />
                    </product_attributes>
                </item>
            </quote>
        </sales>
    </global>
</config>

app/code/local/My/Module/Model/Observer.php

class My_Module_Model_Observer extends Mage_Core_Model_Observer
{
    public function disallowProductAddToCart(Varien_Event_Observer $observer)
    {
        $quote = $observer->getQuoteItem();
        $cartItems = $quote->getQuote()->getAllItems();

        if (count($cartItems) > 1) {
            $product = $observer->getProduct();
            $isPreorder = $product->getPreorder();

            if ($isPreorder) {
                $quote->getQuote()->removeItem($quote->getId());
                Mage::throwException(
                    Mage::helper('sales')->__('Can not add pre-order product to existing cart.')
                );
            }

            foreach ($cartItems as $item) {
                if (!$isPreorder && $item->getProduct()->getPreorder()) {
                    $quote->getQuote()->removeItem($quote->getId());
                    Mage::throwException(
                        Mage::helper('sales')->__('Cart already contains an pre-ordered product.')
                    );
                    break;
                }
            }
        }
    }
}

Edit: allow multiple "pre-order" products in cart

public function disallowProductAddToCart(Varien_Event_Observer $observer)
{
    $quote = $observer->getQuoteItem();
    $cartItems = $quote->getQuote()->getAllItems();

    if (count($cartItems) > 1) {
        $product = $observer->getProduct();
        $isPreorder = $product->getPreorder();

        foreach ($cartItems as $item) {
            if ($isPreorder != $item->getProduct()->getPreorder()) {
                $quote->getQuote()->removeItem($quote->getId());
                $message = $isPreorder ? 'Can not add pre-order product to existing cart.' : 'Cart already contains pre-ordered products.';
                Mage::throwException(
                    Mage::helper('sales')->__($message)
                );
                break;
            }
        }
    }
}

^{If your are curious why using checkout_cart_product_add_after and remove item from cart later $quote->getQuote()->removeItem($quote->getId()) ... it is just because there is no checkout_cart_product_add_before event dispatched in Mage_Checkout_Model_Cart::addProduct() :(}

Related Solutions

Cart – Hide ‘Add to Cart’ Button if Specific Products Already in Cart

If you are unable to save the products into a "special" category as @Julien suggested, you could set a different attribute set specifically for the products, or, if you can do neither of those, I would suggest setting a product attribute. Any way you do it, you'll still have to query the DB for these products, then grab your Cart and see if any items are in it.

So, let's create a product attribute, and call it "featured". Make a new attribute, as a Yes/No and assign it to the appropriate attribute set. Flag those 4 products as such.

Next, you need something along the lines of:

$collection = Mage::getModel('catalog/product')->getCollection();
$collection->addFieldToFilter(array(array('attribute'=>'featured','eq'=>'1'));

$exemptProducts = array();
$exemptProductFound = false;

foreach ($collection as $product) {
    $exemptProducts[] = $product->getId();
}

// now let's check if any are in the basket
$cart = new Mage_Checkout_Model_Cart();
$cart->init();

foreach ($cart->getItems() as $item) {
    if(in_array($item->getProductId(), $exemptProducts)) {
        // to make it simple, just set a flag
        $exemptProductFound = true;
    }
}

This could be in-line in your template, or in a function that you make available to your template (cleaner).

Magento – Check Some Condition Before Product added to cart

The closest events I could find that would work that are lower than the dispatch event are

catalog_product_type_prepare_full_options
catalog_product_type_prepare_lite_options

You can have an event listener on one of those events that does your logic check and throws an exception if it fails.

That being said, Magento itself actually uses the following event

checkout_cart_product_add_after

Then, in the listener is uses code like this

$quoteItem = $observer->getEvent()->getQuoteItem();
$product = $observer->getEvent()->getProduct();
// Your checks here, return if you want to leave things alone
$quoteItem->getQuote()->removeItem($quoteItem->getId());
Mage::throwException('This is the message to the customer');

Best Answer

Related Solutions

Cart – Hide ‘Add to Cart’ Button if Specific Products Already in Cart

Magento – Check Some Condition Before Product added to cart

Related Topic