if you want this filtering to be done in model, you should have first your filtered data, then override it in context when passing to view.  or pass altered values together in order to keep things in stable condition.

values['filtered_stuff'] = filtered_stuff
return request.module.render("module.view" values)

Hi Bouabaker,

Thanks for your answer, unfortunately it wasn't what I was looking for.

Anyway, we found the solution,

Thanks!

Hi 

IfI understand, you will want something similar to showing customers, for example in the invoice without the suppliers

domain="[('customer', '=', True)]"

This requires two things to increase a true or false probability, for example

<field string="Customer" name="partner_id"   domain="[('customer', '=', True)]"/>

If you have the code to understand the problem more