[GNC] Scheduled Transaction Calculations

[Fross, Michael]

Hi John,

I got it to work, but one challenge remains.  The load-from-path seems to
crash Gnucash.  But copying the app-utils.scm to the fin.scm folder solves
the problem, but it's sloppy.

I'll need to play around with it.

Secondly, I it didn't like the name "days-in-prev-mon"  But I shortened it
and took out the dashes and that seems ok.  Here is what I inserted in
fin.scm:

;; Return number of days in the previous month
(load-from-path "C:\Program Files
(x86)\gnucash\share\gnucash\scm\gnucash\app-utils")
(define (gnc:numdayslastmon)
   (/
      (+ 1
         (- (gnc:get-end-prev-month) (gnc:get-start-prev-month))) 86400)
)


Thanks again for your help!

Michael

On Fri, Nov 1, 2019 at 3:25 PM Fross, Michael <michael at fross.org> wrote:

> Thanks John.  I'll give is a shot and report back.
>
> Michael
>
> On Fri, Nov 1, 2019 at 2:34 PM John Ralls <jralls at ceridwen.us> wrote:
>
>>
>>
>> > On Nov 1, 2019, at 9:36 AM, Fross, Michael <michael at fross.org> wrote:
>> >
>> > Hello all,
>> >
>> > I have a scheduled transaction that I pay monthly which is a fixed
>> amount
>> > per day.  I'd love to be able to have is automatically entrer based on
>> the
>> > number of days per month.  I pay on the 1st (or the first business day
>> > after that) so basically I'd like to use the following formula:
>> >
>> > Amount = NumDaysInPreviousMonth * AmountPerDay
>> >
>> > I looked through the guide
>> > <https://wiki.gnucash.org/wiki/Scheduled_Transactions> and didn't see
>> > anything.  It references fin.scm (link throws a 404 by the way) but I
>> > didn't see anything here that calculated the number of days in the
>> previous
>> > month (but perhaps I missed it in the SCM code.)
>> >
>> > This seems like a simple use case, am I missing something? Perhaps I'll
>> > need to write a function in fin.scm that can return the number of days
>> in a
>> > provided month.  No idea how to use scheme, but I'm sure I can figure it
>> > out.
>> >
>> > Thoughts?
>>
>> I fixed the link.
>>
>> The closest functions in GnuCash would be gnc:get-start-prev-month and
>> gnc:get-end-prev-month. They return time64 so you'd divide the difference
>> by 86400 (the number of seconds in a day) after adding in 1 second to
>> compensate for gnc:get-start-prev-month's returning the first second of the
>> month rather than the last second of the month before.
>>
>> You could try adding this to fin.scm:
>>
>> (load-from-path "gnucash/app-utils")
>> (define (gnc:days-in-prev-month) (/ ( + 1 (- (gnc:get-end-prev-month)
>> (gnc:get-start-prev-month)))) 86400))
>>
>> Then use
>>   days-in-prev-month() * AmountPerDay
>> in your scheduled transaction. Replace "AmountPerDay" with the actual
>> numeric amount or the Since Last Run dialog will ask for the amount every
>> month.
>>
>> I've never actually tried doing anything like that, but it might work.
>>
>> Regards,
>> John Ralls
>>
>>
>>
>>