Remove required on sequence

review348001

dashboard.py

@@ -1,6 +1,8 @@
 #This file is part of Tryton.  The COPYRIGHT file at the top level of
 #this repository contains the full copyright notices and license terms.
 from trytond.model import ModelView, ModelSQL, fields
+from trytond.transaction import Transaction
+from trytond.backend import TableHandler
 
 
 class DashboardAction(ModelSQL, ModelView):
@@ -9,7 +11,9 @@ class DashboardAction(ModelSQL, ModelView):
 
     user = fields.Many2One('res.user', 'User', required=True,
             select=True)
-    sequence = fields.Integer('Sequence', required=True)
+    sequence = fields.Integer('Sequence',
+        order_field='(%(table)s.sequence IS NULL) %(order)s, '
+        '%(table)s.sequence %(order)s')
     act_window = fields.Many2One('ir.action.act_window', 'Action',
             required=True, ondelete='CASCADE', domain=[
                 ('res_model', '!=', None),
@@ -20,4 +24,13 @@ class DashboardAction(ModelSQL, ModelView):
         super(DashboardAction, self).__init__()
         self._order.insert(0, ('sequence', 'ASC'))
 
+    def init(self, module_name):
+        cursor = Transaction().cursor
+        table = TableHandler(cursor, self, module_name)
+
+        super(DashboardAction, self).init(module_name)
+
+        # Migration from 2.4: drop required on sequence
+        table.not_null_action('sequence', action='remove')
+
 DashboardAction()