[FIX] mass_mailing_partner: compute fields performance (#271)

- In DB which use large amounts of records and intesive use of
mass_mailings, not optimized compute records lead to a drastical
decrease of performance

mass_mailing_partner/__manifest__.py

@@ -1,13 +1,12 @@
 # -*- coding: utf-8 -*-
 # Copyright 2015 Pedro M. Baeza <pedro.baeza@tecnativa.com>
-# Copyright 2015 Antonio Espinosa <antonio.espinosa@tecnativa.com>
+# Copyright 2015-2016 Antonio Espinosa <antonio.espinosa@tecnativa.com>
 # Copyright 2015 Javier Iniesta <javieria@antiun.com>
-# Copyright 2016 Antonio Espinosa - <antonio.espinosa@tecnativa.com>
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
 
 {
     "name": "Link partners with mass-mailing",
-    "version": "10.0.1.0.2",
+    "version": "10.0.1.0.3",
     "author": "Tecnativa, "
               "Odoo Community Association (OCA)",
     "website": "https://www.tecnativa.com",

mass_mailing_partner/models/res_partner.py

@@ -36,17 +36,29 @@ class ResPartner(models.Model):
                     _("This partner '%s' is subscribed to one or more "
                       "mailing lists. Email must be assigned.") % partner.name)
 
+    @api.multi
     @api.depends('mass_mailing_contact_ids',
                  'mass_mailing_contact_ids.opt_out')
     def _compute_mass_mailing_contacts_count(self):
-        for reg in self:
-            reg.mass_mailing_contacts_count = len(
-                reg.mass_mailing_contact_ids)
+        contact_data = self.env['mail.mass_mailing.contact'].read_group(
+            [('partner_id', 'in', self.ids)], ['partner_id'], ['partner_id'])
+        mapped_data = dict(
+            [(contact['partner_id'][0], contact['partner_id_count'])
+             for contact in contact_data])
+        for partner in self:
+            partner.mass_mailing_contacts_count = mapped_data.get(partner.id,
+                                                                  0)
 
+    @api.multi
     @api.depends('mass_mailing_stats')
     def _compute_mass_mailing_stats_count(self):
-        for reg in self:
-            reg.mass_mailing_stats_count = len(reg.mass_mailing_stats)
+        contact_data = self.env['mail.mail.statistics'].read_group(
+            [('partner_id', 'in', self.ids)], ['partner_id'], ['partner_id'])
+        mapped_data = dict(
+            [(contact['partner_id'][0], contact['partner_id_count'])
+             for contact in contact_data])
+        for partner in self:
+            partner.mass_mailing_stats_count = mapped_data.get(partner.id, 0)
 
     def write(self, vals):
         res = super(ResPartner, self).write(vals)