[GNC] Scripted price editing and adding

[Raymond Smith]

Hi, Gnucash list.

I'm interested in using a script to add and edit prices in my Gnucash file.
For example, I'd like to
(a) loop over a file containing historical price data and add prices for
dates where the price is missing because I didn't do a quote retrieval in
Gnucash that day
(b) loop over the prices I have of one security and add prices for call
options using max(0, security price - strike price).
I would prefer working in Python if possible, and I'm looking for guidance
on the right approach.

I've seen there are some Python bindings and also the piecash library, but
it's not clear to me how well maintained or supported either is right now.
I found relatively little documentation on the Python bindings (
https://wiki.gnucash.org/wiki/Python_Bindings). Piecash looks very nice,
and I was able to set up a simple example where I added a price using it.
But, it currently has a very minor issue (
https://github.com/sdementen/piecash/issues/126) that prevented it from
running on my recent gnucash save files without a simple fix. Not a big
deal to do that, but I'd like to avoid tying myself to a library that
stalls while Gnucash and my save files continue to evolve.

Another option I've thought about is to parse xml files using something
like Python's xml library. That seems reasonably straightforward at first
glance, but perhaps there are some things I should be aware of that I'm
missing that would make this a bad idea? One question that has already come
up is how to manage guid's of the prices. Can they be any string of the
appropriate length as long as each is unique within the file? I tried a
super simple test file where I copied one <price></price> block and changed
the date, price, and guid, then re-opened the file, and it seemed to work,
but I'm not sure if that's dangerous.

Many thanks for any guidance or insights you may have.
Ray