Empty numeric input elements in a form send some data to my collection, while I'd like numeric fields to remain empty is nothing was entered

Here it is the code behind my input elements.

Even if #priceInput is hiden and the user doesn’t enter any data, you’ll find something in the price field in my collection. This happen only to numeric fields. If the field were text type as the valuta field then it would be empty as you can see. And I need numeric fileds to remain empty when nothing is entered.

So, the final result is the following: