scheme to retrieve the customer associated with a transaction

[Macho Philipovich]

     I'm not particularly interested in whether specific entries in a
     Bill were marked as "Billable"—but only in determining which job and
     customer were set as the default chargebacks for the overall Bill.
     Glancing at the Gnucash source code, it looks to me as though
     something as simple as (gncInvoiceGetBillTo invoice) should do what
     I need, and return a GncOwner object representing either the job or
     customer, when these are set, or () when neither are. But I'm
     getting back () even for bills for which I believe a chargeback job
     has been set.

   Ok, I finally figured it all out!
   It turns out that on Wednesday when I asked for "a couple of lines of
   code" to find the customer name and job objects associated with a
   particular split (chargebacks when it's a bill), what I in fact needed
   was something like this:
   (define find-lot
     (lambda (lots)
       (if (null? lots)
         '()
         (if (null? (car lots)) (find-lot (cdr lots)) (car lots)))))
   …
     (let* (parent (xaccSplitGetParent split))
       (split-list (xaccTransGetSplitList parent))
       (lots       (map (lambda (x) (xaccSplitGetLot x)) split-list))
       (invoice    (gncInvoiceGetInvoiceFromLot (find-lot lots)))
       (billTo     (gncInvoiceGetBillTo invoice))
       (isBill?    (string=? (gncInvoiceGetTypeString invoice) "Bill"))
       (owner      (if isBill? billTo (gncInvoiceGetOwner invoice)))
       (job        (gncOwnerGetJob owner))
       (ownername  (gncOwnerGetName (gncJobGetOwner job)))
       (jobname    (gncJobGetName job))
   …
   Now that I've got this done I can painlessly create multiple accounting
   reports that I'm required by law to produce every month. Thanks so much
   to the wonderful Gnucash developers!
   —m