Can I inherit from a standard report in OpenERP?

Question

I want to make changes to the purchase order report in OpenERP 6.1. Do I have to go in and make changes to the purchase module, or can I create a new module that will inherit the standard report and override some details.

Answer 1

You can't exactly inherit another report and just override some details, but you can replace a standard report and make all existing links to it launch your new report instead.

Our zaber_purchase module contains some changes to the purchase order report that our users wanted. Here's the purchase_report.xml file that replaces the standard report with ours.

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
        <report 
            auto="False" 
            id="purchase.report_purchase_order" 
            model="purchase.order" 
            name="purchase.order.zaber"
            rml="zaber_purchase/report/order.rml" 
            string="Purchase Order"
            usage="default"/>
    </data>
</openerp>

Since it's not inheriting but replacing the report, you have to duplicate the whole report in your version. Your report's id has to match the original report's id, including the module name. In the example above, the original report has an id of report_purchase_order, and it's part of the purchase module, so your report id must be purchase.report_purchase_order to replace it. The name has to match the name in your version's parser file, and the rml attribute has to point to your version's RML file.

Thanks to mihai for explaining most of this in the OpenERP forum.