Hi friends, 

I added a custom field to customers and in reporting, i must do invoice analysis according to that custom field. This custom field must be in 'group by'. For that purpose , i tried to add this line "filter string="Sales District" context="{'group_by':'partner_id.x_sales_district'}"/>" in serach view of invoice analysis. But i got an error that says 'undefined type'. Where am i wrong about ?

Thanks in advance.