I have a 3 char fields and 1 many2many field. Below is code

brand = fields.char ('Brand')

lang = fields.char ('Language')

ref = fields.char ('Reference')

product_ids = fields.Many2many ('product.product', Products')

How can i hide fields based on many2many multiple selection? Example if product A selected selected then BRAND should be visible and when product B selected LANG should be visible, when Product C selected then REF should be visible vice versa.

There can be multiple selection like product A and B selected together then BRAND & LANG both visible.

Please note I dont want to use boolean fields for hiding char fields