[FIX] website : fix partner visitors field definition

visitor.partner is a many2one to partner. But partner.visitor_ids is a
many2many.

The result is when you set the partner_id on visitor, the (what should be)
inverse field is not set accordingly.

This inverse field should be a one2many fields. This commit fixes the field
definition.

Task ID: 2127691
PR #40577

Related: odoo/upgrade#905
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/website/models/res_partner.py

@@ -9,7 +9,7 @@ class Partner(models.Model):
     _name = 'res.partner'
     _inherit = ['res.partner', 'website.published.multi.mixin']
 
-    visitor_ids = fields.Many2many('website.visitor', 'website_visitor_partner_rel', 'partner_id', 'visitor_id', string='Visitors')
+    visitor_ids = fields.One2many('website.visitor', 'partner_id', string='Visitors')
 
     def google_map_img(self, zoom=8, width=298, height=298):
         google_maps_api_key = self.env['website'].get_current_website().google_maps_api_key

addons/website/tests/test_website_visitor.py

@@ -67,7 +67,6 @@ class WebsiteVisitorTests(tests.HttpCase):
         })
         partner_demo = self.env.ref('base.partner_demo')
         old_visitor.partner_id = partner_demo.id
-        partner_demo.visitor_ids = [(6, 0, [old_visitor.id])]  # TODO DBE : Remove this line in Master (13.1) after visitor_ids field declaration master fix
         self.assertEqual(partner_demo.visitor_ids.id, old_visitor.id, "The partner visitor should be set correctly.")
 
         # archive old visitor