Update a field on drupal commerce

Question

I have a product field that takes a number as an input(quantity) and w sometimes this quantity becomes empty so I want with the module Commerce Feeds to update this field from sth to empty .But it keeps not updating the field with nothing(empty).

I might say that I need to do it automatically and not manually

Answer 1

1. You may want to look into the commerce stock module. That's what you sound like your using this quantity field for. http://drupal.org/project/commerce_stock

2. Did you create this product via feeds? Feeds can only update items that are created with feeds.