Try below code

       if view_type =='form':
            doc = etree.XML(result['fields']['order_line']['views']['tree']['arch'])
            node = doc.xpath("//field[@name='product_id']")[0]
            node.set('invisible','1')
            result['fields']['order_line']['views']['tree']['arch'] = etree.tostring(doc)
        return result

Hope it will help you.

I can't do it in the xml file, because i have to show/hide the column, depending of attributes like company_id.

Since now i can't find 'order_line <tree> columns in the doc.xpath, so i cannot replace or hide the fields.

Kind regards.

try this.

from openerp.osv.orm import setup_modifiers

if doc.xpath("//field[@name='order_line']/tree//field[@name='product_id']"):

    node = doc.xpath("//field[@name='order_line']/tree//field[@name='product_id']")[0]

    node.set('invisible', '1')

    setup_modifiers(node, res['fields']['product_id'])

res['arch'] = etree.tostring(doc)

return res

OR

<xpath expr="//field[@name='order_line']//tree//field[@name='product_id']" position="attributes">

           attribute name="invisible">1</attribute>

</xpath>

I hope it's useful for you.