OpenERP - implementing something similar to stock.picking.in - openerp-7

Question

The way stock.picking.in is implemented in openERP is interesting. I am trying to do something similar with purchase orders.
Stock.picking.in inherits from stock.picking, customizes a few columns and defaults and declares the table as stock_picking. On the UI side, a form view is inherited from view_picking_form and the model used is stock.picking.in.
I am trying to do something similar by creating a special purchase order. The problem is that the form for the special PO never gets picked up. It always shows a dynamic view with all fields of the PO dumped in some default manner. The developer mode also does not show the right form view.
When I check Settings -> User Interface -> Views, it does show the view properly but doesn't display it when I create new special PO.
Here is the code:
class my_purchase_order(osv.osv):
_name = "purchase.order"
_inherit = "purchase.order"
_columns={
...
}
my_purchase_order()
class my_purchase_order_special(osv.osv):
_name = 'purchase.order.my_special'
_inherit = "purchase.order"
_table = "purchase_order"
_columns = {...
}
my_purchase_order_special()
<record id="po_my_special_form" model="ir.ui.view">
<field name="name">po_my_special_form</field>
<field name="model">purchase.order.my_special</field>
<field name="type">form</field>
<field name="inherit_id" ref="purchase.purchase_order_form" />
<field name="arch" type="xml">
...
</field>
</record>
<record id="po_my_special_tree" model="ir.ui.view">
<field name="name">po_my_special_tree</field>
<field name="model">purchase.order.my_special</field>
<field name="arch" type="xml">
<tree fonts="bold:message_unread==True" colors="grey:state=='cancel';blue:state in ('wait','confirmed');red:state in ('except_invoice','except_picking')" string="Purchase Order">
<field name="message_unread" invisible="1"/>
<field name="name" string="Reference"/>
<field name="date_order" />
<field name="partner_id"/>
<field name="company_id" groups="base.group_multi_company" widget="selection"/>
<field name="minimum_planned_date" invisible="context.get('quotation_only', False)"/>
<field name="origin"/>
<field name="amount_untaxed" sum="Total Untaxed amount" string="Untaxed"/>
<field name="amount_total" sum="Total amount"/>
<field name="state"/>
</tree>
</field>
</record>
<record id="action_po_my_special_tree" model="ir.actions.act_window">
<field name="name">Special Purchase Orders</field>
<field name="type">ir.actions.act_window</field>
<field name="res_model">purchase.order.my_special</field>
<field name="view_mode">tree,form,graph,calendar</field>
<field name="context">{}</field>
<field name="domain">[('state','=','draft')]</field>
<field name="search_view_id" ref="purchase.view_purchase_order_filter"/>
</record>
<record id="action_po_my_special_form" model="ir.actions.act_window.view">
<field eval="2" name="sequence"/>
<field name="view_mode">form</field>
<field name="view_id" ref="po_my_special_form"/>
<field name="act_window_id" ref="action_po_my_special_tree"/>
</record>
Please advise. Thanks in advance.

Answer 1

Turns out I was missing view records:
<record id="action_po_my_special_tree2" model="ir.actions.act_window.view">
<field eval="1" name="sequence"/>
<field name="view_mode">tree</field>
<field name="view_id" ref="po_my_special_tree"/>
<field name="act_window_id" ref="action_po_my_special_tree"/>
</record>
<record id="action_po_my_special_form2" model="ir.actions.act_window.view">
<field eval="2" name="sequence"/>
<field name="view_mode">form</field>
<field name="view_id" ref="po_my_special_form"/>
<field name="act_window_id" ref="action_po_my_special_tree"/>
</record>