1 Answer
If the category_id is many2many field on partner master, then you can try the following code.
partner_ids = self.env['res.partner'].search([('id','=',partner_id)])
if partner_ids:
category_ids = [contact_tag_id]+partner_ids.category_id.ids
partner_ids.sudo().write({'category_id': [(6, 0, category_ids)]})
So something like this?
partner_ids = self.env['res.partner'].search([('id','=',partner_id)])
if contact_tag_id not in partner_ids.category_id.ids
#Add the tag to contact
if contact_tag_id != None:
project_id = contact_tag_id
env['res.partner'].search([('id','=',partner_id)]).sudo().write({'category_id': [(4, contact_tag_id)]})
i haven't known your model and type of variable, so i can't fix your code