Delete row from table once user click on Add to cart

Question

When user remove the Previously added item from cart, than it will be removed from Database table : sales_flat_quote_item_option, i need similar feature.

Question : once Registered user click on custom button "save design" in product view page , we are creating new row in my_designs table and creating new product and saving product information in database.

once customer click on "add to cart" for that product, we want to remove that product information from "my_designs" table. we want to delete that row.

we are using below code to add the product to cart

<?php echo $this->getMessagesBlock()->getGroupedHtml() ?>

<?php $collections = $this->getCollection(); ?>

<?php $_product = $this->getProduct(); ?>

<div id="messages_product_view">
<?php $buttonTitle = Mage::helper('core')->quoteEscape($this->__('Add to Cart')); ?>
</div>

<?php foreach ($collections as $key => $product) {

    echo $product->getName().' <br>';
?>
<form action="<?php echo  Mage::helper('checkout/cart')->getAddUrl($product);?>" method="post">  
<div class="add-to-cart-buttons">

<button type="submit" title="<?php echo $buttonTitle ?>" class="button btn-cart" >
    <span><span>
    <?php echo $buttonTitle ?>
    </span></span>
</button>

<?php echo $this->getChildHtml('', true, true) ?>

</div>
</form>
<hr style='display:inline-block; width:100%;'>
<?php

}
?>

Answer 1

First create an observer in your code config.xml

<frontend>
    ........
    <events>
        <checkout_cart_product_add_after>
            <observers>
                <delete_save_design_row>
                    <class>Amasty_Example_Model_Observer</class>
                    <method>_deletedesign</method>
                </delete_save_design_row>
            </observers>
        </checkout_cart_product_add_after>
    </events>
    .........
</frontend>

Now create a new file Amasty/Example/Model/Observer.php with below code

<?php

class Amasty_Example_Model_Observer
{
    public function _deletedesign($observer)
    { 
        $productId = $observer->getProduct()->getId();
        $customerId = Mage::getSingleton('customer/session')->getCustomer()->getId();
        $collection = Mage::getModel('example/mydesign')->getCollection()
                ->addFieldToFilter('product_id', $productId)
                ->addFieldToFilter('customer_id', $customerId);
        $collection->walk("delete");
    }
}
?>

Answer 2

use controller_action_postdispatch_checkout_cart_add event refer link

get product id from param and customer id from session

use above both id to delete entry from your table

UPDATE Query to delete entry

$collection = Mage::getResourceModel('amasty/mydesign_collection')
        ->addFieldToFilter('product_id', <YOUR_PRODUCT_ID)
        ->addFieldToFilter('customer_id', <CUSTOMER_ID);
$collection->walk("delete");

Answer 3

You can use a trigger for that :

CREATE TRIGGER deleteDesign
    ON sales_flat_quote_item
    FOR DELETE
AS
    DELETE FROM my_designs
    WHERE product_id = (SELECT deleted.id FROM deleted) AND customer_id = (SELECT deleted.customer_id FROM deleted)
GO

When an item is removed from sales_flat_quote_item table, it will delete it from my_designs.