Force Variants when adding to cart

-- url of the page with the problem -- : girlygeekclothing.com/women/womens-shirt...trash-womens-t-shirt
-- HikaShop version -- : 2.2.1
-- Joomla version -- : 3.2
-- PHP version -- : 5.3.8
-- Browser(s) name and version -- : FIREFOX 27.0.1
-- Error-message(debug-mod must be tuned on) -- : Error_message

Hello-

I currently have our "Add to Cart" button hidden until the user chooses one of each of the products available characteristics.

We would like to change it so that the button is there on page load but if pressed and no variants chosen then fire two events -
1. Add a class to the variants/characteristics that need to be selected.
2. set "display block" to a hidden div next to the variants with an error message.

End result would look like the error when adding a product here -
www.victoriassecret.com/clothing/all-top...54&CatalogueType=OLS


I have been trying to stop the buttons add to cart functionality using a template override with a custom hikashop_button_render function, and also tried modifying cart.php, but not able to figure it out. I know I should be able to do it with a combination of php and Jquery but no luck.

Any direction or suggestions would be great, thank you!

-Billy

Thank you so much for the direction Nicolas. I put the following code in the quantity view at line 20 and its working great. I am now just adding the error message warning the user to "choose a variant", and highlight the radio's and I am good to go.

$this->ajax = '
	var chosenVariant = document.getElementById(hikashop_product_quantity_field_1);
	if (chosenVariant = \'hikashop_product_quantity_field_1\') {
		return false;
	}
	else {
		return hikashopModifyQuantity(\''.$this->row->product_id.'\',field,1,0,\'cart\','.$module_id.')
	}';

-

Nice collection! Thanks for the post.