The OpenCart 3. Create a form to search for goods by attributes

There was a site on Opencart 3, and a line of form was created. It was necessary to make that when entering the data form, a search for the attributes of the goods was carried out.

To do this, it was necessary to create their functions in the model and controller, which carried out a search for the selected attributes of the product (responsive the fields in the form), and returned the list of suitable products to the search page.