Accept changing ticket category without changing sub category

website_support/models/website_support_ticket.py

@@ -109,6 +109,14 @@ def _default_approval_id(self):
     sla_alert_ids = fields.Many2many('website.support.sla.alert', string="SLA Alerts",
                                      help="Keep record of SLA alerts sent so we do not resend them")
 
+    #add constrains on sub_category_id
+    @api.constrains('sub_category_id')
+    def _check_subcategory(self):
+        # if the sub_category_id not a child of the selected category then raise an error.
+        if any(ticket.sub_category_id and ticket.sub_category_id.parent_category_id != ticket.category for ticket in self):
+            raise ValidationError(_('Error: Your selected sub category not a child of the parent category.'))
+        return True
+
     @api.multi
     @api.depends('subject', 'ticket_number')
     def name_get(self):
@@ -799,4 +807,4 @@ def send_reply(self):
         else:
             #Change the ticket state to staff replied
             staff_replied = self.env['ir.model.data'].get_object('website_support','website_ticket_state_staff_replied')
-            self.ticket_id.state = staff_replied.id
+            self.ticket_id.state = staff_replied.id