from odoo import models, fields
from odoo.exceptions import UserError, ValidationError

class GroupPartner(models.Model):
    _name = 'group.partner'

    name = fields.Char(string='Name')

class ResPartner(models.Model):
    _inherit = 'res.partner'

    reference_number = fields.Char(string="Reference Number")
    company_type_id = fields.Many2one('res.partner.company_type', string='Company Type')
    custom_pricelist_id = fields.Many2one('product.pricelist', string='Price Matrix')
    group_partner_id = fields.Many2one('group.partner', string='Group Partner')

    def unlink(self):
        if self._name == 'res.partner':
            raise UserError('Maaf anda tidak bisa delete contact')