[FIX] fleet: prevent deletion of vehicle contract

When we create a contract information on a vehicle, there is an activation cost
automatically created. Before this fix, if we delete the activation cost line, it
deletes automatically the associated contract. We should prevent this and add a
warning message instead.

To make it easier for the user, we should also show the contract information on
the list and form views of the vehicule cost.

When deleting the vehicle contract, we should also automatically delete the
activation cost line associated.

closes odoo/odoo#72269

Signed-off-by: Alex Tuyls <alt-odoo@users.noreply.github.com>

addons/fleet/i18n/fleet.pot

@@ -2312,6 +2312,12 @@ msgstr ""
 msgid "You can define several models (e.g. A3, A4) for each make (Audi)."
 msgstr ""
 
+#. module: fleet
+#: code:addons/fleet/models/fleet_vehicle_cost.py:76
+#, python-format
+msgid "You cannot delete an activation cost linked to a contract. You should delete the contract instead."
+msgstr ""
+
 #. module: fleet
 #: model_terms:ir.ui.view,arch_db:fleet.fleet_vehicle_log_contract_view_form
 msgid "amount"

addons/fleet/models/fleet_vehicle_cost.py

@@ -70,6 +70,11 @@ class FleetVehicleCost(models.Model):
                 del data['odometer']
         return super(FleetVehicleCost, self).create(vals_list)
 
+    @api.multi
+    def unlink(self):
+        if self.contract_id:
+            raise UserError(_('You cannot delete an activation cost linked to a contract. You should delete the contract instead.'))
+        return super(FleetVehicleCost, self).unlink()
 
 class FleetVehicleLogContract(models.Model):
     _inherit = ['mail.thread', 'mail.activity.mixin']
@@ -187,6 +192,14 @@ class FleetVehicleLogContract(models.Model):
             self.activity_reschedule(['fleet.mail_act_fleet_contract_to_renew'], date_deadline=vals.get('expiration_date'), new_user_id=vals.get('user_id'))
         return res
 
+    @api.multi
+    def unlink(self):
+        cost_to_unlink = self.cost_id
+        res = super(FleetVehicleLogContract, self).unlink()
+        if cost_to_unlink:
+            cost_to_unlink.unlink()
+        return res
+
     @api.multi
     def contract_close(self):
         for record in self:

addons/fleet/views/fleet_vehicle_cost_views.xml

@@ -10,6 +10,7 @@
                     <field name="description"/>
                     <field name="cost_subtype_id"/>
                     <field name="date"/>
+                    <field name="contract_id"/>
                 </tree>
             </field>
         </record>
@@ -126,6 +127,7 @@
                             </group>
                             <group>
                                 <field name="date"/>
+                                <field name="contract_id"/>
                                 <field name="parent_id" groups="base.group_no_one"/>
                             </group>
                         </group>