Hello

I am using the free-tier of odoo online.

I need to create a report that is organised by product variant (types of service sold).  to report on all sales of that product variant by customer reference number and filtered by when the invoice associated was paid.   i.e. product variant->customer reference number->total receipts in calendar year xx.

I cannot see a report that can be exported to provide this data offline (for querying via excel) so I assume I will have to write this report myself.  However the next hurdle is that I cannot see where to find an exhaustive list of all fields and their relationships so that the query can be written. 

can anyone assist here please?