social/mass_mailing_partner/models/mail_mass_mailing.py

# Copyright 2015 Pedro M. Baeza <pedro.baeza@tecnativa.com>
# Copyright 2015 Antonio Espinosa <antonio.espinosa@tecnativa.com>
# Copyright 2015 Javier Iniesta <javieria@antiun.com>
# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).

from odoo import api, fields, models, _
from odoo.exceptions import ValidationError


class MailMassMailingList(models.Model):
    _inherit = 'mail.mass_mailing.list'

    partner_mandatory = fields.Boolean(string="Mandatory Partner",
                                       default=False)
    partner_category = fields.Many2one(comodel_name='res.partner.category',
                                       string="Partner Tag")

    @api.constrains('contact_ids')
    def _check_contact_ids_partner_id(self):
        contact_obj = self.env['mail.mass_mailing.contact']
        for mailing_list in self:
            data = contact_obj.read_group(
                [
                    ('id', 'in', mailing_list.contact_ids.ids),
                    ('partner_id', '!=', False),
                ],
                ['partner_id'], ['partner_id']
            )
            if len(list(filter(lambda r: r['partner_id_count'] > 1, data))):
                raise ValidationError(_("A partner cannot be multiple times "
                                        "in the same list"))