Altering add_to_cart_form_submit() and random PDOException while adding to cart

Question

I have created a customized product with lots of attributes to set for it. I also altered hook_add_to_cart_form_submit() where I collect all selected attributes and calculate a new price based on the selected and configured attributes. So in my

function MYMODULE_add_to_cart_form_submit($form, &$form_state) {}

I create a big array and:

if (empty($form_state['line_item']->line_item_id)) {
    if ($attributes)
        $form_state['line_item']->data['context']['attributes'] = $attributes;
    $line_item = commerce_product_line_item_new($product, $form_state['values']['quantity'], 0, $form_state['line_item']->data, $form_state['line_item']->type);
    //   ...
}

I'm not sure if I am doing it right, I just want to store that array in the line-item table. While adding product to cart randomly I get:

"PDOException: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry 'commerce_line_item-177-0-0-und' for key 'PRIMARY': INSERT INTO {field_data_commerce_unit_price} ..."

error. Should I use some special format for this $attribute array? Everything is stored as BLOB in commerce_line_item.data field.

Answer 1

When you call commerce_product_line_item_new, drupal is trying to insert an already existant record to the table field_data_commerce_unit_price which has it's primary key defined as :

PRIMARY KEY (entity_type,entity_id,deleted,delta,language),

Since the product already exists, it fails with a constraint violation error :

Integrity constraint violation: 1062 Duplicate entry

What you are trying to do could be accomplished by adding a new cost item to the current order based on the attributes you mention, not by modifying the current item price which I guess is what you are trying to do.

So IMHO, you may try to have a base price for your item (or even a 0 price) and once the customer adds it to cart, add another cost item with the charges calculated based on the attributes he sets.