Hi,

You can hook into catalog events.

http://world.episerver.com/documentation/Items/Developers-Guide/EPiServer-Commerce/8/Content/catalog-events/

http://world.episerver.com/blogs/K-Khan-/Dates/2015/5/hook-into-catalog-events/

In theory this should work

var contenEventHandler = EPiServer.ServiceLocation.ServiceLocator.Current.GetInstance<EPiServer.Core.IContentEvents>();
                contenEventHandler.SavingContent += contenEventHandler_SavingContent;

void contenEventHandler_SavingContent(object sender, ContentEventArgs e)
        {
//your conditions and actions
            e.CancelAction = true;
        }

Regards
/K

Thanks Khan,

The idea is to prevent saving a product and show the client a error msg if the assets list is empty, or some other condition in assets.

I will try the eventHandler...

Juan