I am currently running Odoo v13 Community Edition and I am finding a few problems I need help with.

So I am trying to use the env('purchase.order').search() method to find a specific purchase order. I am using this function in the purchase.order.line model.

The specific purchase order record I need is the record that the order line is in. I do not know how do I get that record. I specifically want a field inside the purchase order model called "currency_rate". There is only 1 currency_rate value per purchase order but the values can differ from one purchase order to another. The currency_rate field has the label "Currency Rate".

Can anyone help me please?

Thank you in advance