We need to domain filter options in a many2one field, based on selected value in another field.

Our setup example:

In Model A we have following many2one fields:

Product type (x_studio_field_C8Ncm)

Product (x_studio_field_y8xyP)

We need product to be domain filtered based on value set in product type.

Ie. if we choose product type: phone it has to filter options in products like iPhone, Galaxy etc. Not Macbook or whatever.

After extensively searching the forums and reading various linked documentations on api.onchange functions, I tried many compute field variations like this:

from odoo import api

@api.onchange('x_studio_field_C8Ncm')

def onchange_partner_id(self):

    for rec in self:

        return {'domain': {'x_studio_field_y8xyP': [('x_studio_field_C8Ncm_id', '=', self.x_studio_field_C8Ncm.id)]}}

With dependency:  x_studio_field_C8Ncm

However it returns error: 

raise ValueError("forbidden opcode(s) in %r: %s" % (expr, ', '.join(opname[x] for x in codes)))
ValueError: forbidden opcode(s) in "from odoo import api\r\n@api.onchange('x_studio_field_C8Ncm')\r\ndef onchange_partner_id(self):\r\n    for rec in self:\r\n        return {'domain': {'x_studio_field_y8xyP': [('x_studio_field_C8Ncm_id', '=', self.x_studio_field_C8Ncm.id)]}}": IMPORT_NAME, IMPORT_FROM

We are running Odoo 13.0 and odoo studio.

Ps. we also have a many2many field where we want similar domain filtering based on other field value. But may put that in different question if the same function cant be applied?

Please help.