Hello , I am trying to sort my records in my tree view , I have a selection field called as _STATES when I try to sort my view according to that , it sorts in correctly, my code and details:

py code

_STATES = [
    ('1_draft', 'To - Do'),
    ('10_in_progress', 'In Progress'),
    ('20_approval', 'Approval'),
    ('30_closed', 'Closed'),
    ('40_cancelled', 'Cancelled')
]

state = fields.Selection(_STATES, 'State', required=True, default="1_draft"
                         )

XML Code

<tree string="Action">
    <field name="name"/>
    <field name="state"/>
</tree>

When I click states field on my tree view to sort my records , it sorts them incorrectly.

The sorting my model makes:

1)10_in_progress

2)1_draft

3)20_approval

4)30_closed

5)40_cancelled

The sorting I want to have:

1)1_draft

2)10_in_progress

3)20_approval

4)30_closed

5)40_cancelled