[ADD] mass_mailing_event: add mass mailing UX on event for attendees

If the event has some attendees a button is displayed to launch a mass
mailing on those attendees. This button requires a new bridge module
between mass mailing and event.

addons/mass_mailing_event/__init__.py

@@ -0,0 +1,4 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+import models

addons/mass_mailing_event/__manifest__.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+{
+    'name': 'Mass mailing on attendees',
+    'category': 'Hidden',
+    'version': '1.0',
+    'description':
+        """
+Mass mail event attendees
+=========================
+
+Bridge module adding UX requirements to ease mass mailing of event attendees.
+        """,
+    'depends': ['event', 'mass_mailing'],
+    'data': [
+        'views/event_views.xml'
+    ],
+    'auto_install': True,
+}

addons/mass_mailing_event/models/__init__.py

@@ -0,0 +1,4 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+import event

addons/mass_mailing_event/models/event.py

@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo import models
+
+
+class Event(models.Model):
+    _inherit = "event.event"
+
+    def action_mass_mailing_attendees(self):
+        mass_mailing_action = dict(
+            name='Mass Mail Attendees',
+            type='ir.actions.act_window',
+            res_model='mail.mass_mailing',
+            view_type='form',
+            view_mode='form',
+            target='current',
+            context=dict(
+                default_mailing_model='event.registration',
+                default_mailing_domain="[('event_id', 'in', %s)]" % self.ids,  # , ('state', 'in', ['draft', 'open', 'done'])
+            ),
+        )
+        return mass_mailing_action

addons/mass_mailing_event/views/event_views.xml

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+<?xml version="1.0"?>
+<odoo>
+    <record id="event_event_view_form_inherit_mass_mailing" model="ir.ui.view">
+        <field name="name">event.event.view.form.inherit.mass.mailing</field>
+        <field name="model">event.event</field>
+        <field name="inherit_id" ref="event.view_event_form"/>
+        <field name="arch" type="xml">
+            <button name="%(event.act_event_registration_from_event)d" position="after">
+                <button class="oe_stat_button" type="object"
+                        name="action_mass_mailing_attendees"
+                        icon="fa-envelope-o"
+                        attrs="{'invisible': [('seats_expected', '=', 0)]}">
+                    Mail Attendees
+                </button>
+            </button>
+        </field>
+    </record>
+</odoo>