openerp domain filters on property of a linked object

Question

Q1. I would like to list only those Incoming Shipments that belong to POs with a certain value in one of the fields of PO. E.g. I have a field called po_type with options, say, 'A', 'B', 'C' etc.

I would like to list only those incoming shipments that belong to POs of po_type = 'A'.

What would the domain filter look like in this case?

EDIT: found the method. It's ('purchase_id.po_type','=','A').

Q2. I have inherited purchase_order_line and added a couple of columns to it. I have added these columns to the order_line grid inside purchase_order form using an xpath.

I now want to set its invisible attribute to true based on the po_type value in its parent. When I use the standard way,

 attrs="{'invisible':[('po_type','=','A')]}" 

it is unable to find po_type, as it obviously is not a line item property but instead belongs to its parent.

How do I make the columns invisible based on a parent's column value?

EDIT: some code:

    <record id="purchase_order_A_form" model="ir.ui.view">
        <field name="name">purchase_order_A_form</field>
        <field name="model">purchase.order</field>
        <field name="type">form</field>
        <field name="inherit_id" ref="purchase.purchase_order_form" />
        <field name="arch" type="xml">
                <xpath expr="//field[@name='order_line']/tree//field[@name='name']" position="after">
                    <field name="my_brand" attrs="{'invisible':[('parent.po_type','!=','A')]}"/>
               </xpath>
               <field name="pricelist_id" select="2" position="after">
                    <field name="po_type"/>
                </field>                   
        </field>
    </record>   

Thanks

Answer 1

I do not thinks its working in openerp now.

attrs="{'invisible':[('parent.po_type','=','A')]}" 

Regards

Answer 2

You can provide a related field of po_type of purchase order in the purchase order line.then add this field as invisible and give the attributes as

attrs="{'invisible':[('po_type',=,'A')]}"

But you need to use the onchange of product_id to change the value of po_type in the lines or you have to use the default get for automatically loading the value of po_type in lines because the data in the related field will be loaded only when you save the record.