Hi,

Please try to use the domain by passing the xml files, in order to apply the domain in action. domain would be the key of action and the value would list of tuples.

try this method,

@api.onchange('bien')
def bien_product(self):
	​context = dict(self._context)
	​write your codes
	​return {'domain': {'bien': [['&',('nom_projet_ids', '=', nom_projet_ids), ('etat_depend_etat', '=', 'dispo')]}}

bien = fields.Many2one('product.template', string="Bien")

Regards