[QGIS-Developer] Accessing GRASS GIS addons from within QGIS

Nyall Dawson nyall.dawson at gmail.com
Wed Feb 6 23:05:14 PST 2019

On Thu, 7 Feb 2019 at 01:41, Nikos Alexandris <nik at nikosalexandris.net> wrote:

> 2) For the Processing Toolbox, my understanding is that it requires
> significant effort to reflect the logic of a GRASS GIS module using
> QGIS' Processing interface to GRASS GIS.  Am I wrong?
> If I go for the Processing option, however, is it possible to inegrate a
> GRASS GIS add-on under the QGIS' Processing GRASS provider, at run-time?
> Essentially, is it possible to write (new) "description" files under
> `python/plugins/processing/algs/grass7/description/` which are likely
> placed under directories owned by the root/admin user?

> If none of the above can ensure access to a GRASS GIS add-on through
> QGIS, one that is to be installed using `g.extension` after having
> installed QGIS and GRASS GIS, what would you then recommend?

My recommendation:

I would implement expose your GRASS add-on as its own processing
provider. You would base this almost entirely off the existing
processing grass provider, but with its own set of description files
exposing only your add on modules. You should be able to do this by
importing the existing grass provider classes, and overwriting the
provider code to have a new ID/name/icon/etc.

This would also make it easy to redistribute - you'd wrap your
provider into a plugin, and then could distribute via the normal
plugin channels. And if you do it right (and only import existing
processing grass code, minimising the copy/paste of this code), then
you're provider will automatically inherit any future fixes and
features added to the main grass provider.


> Do only core GRASS GIS modules work for any of the above mentioned
> options?
> Thank you,
> Nikos Alexandris
> --
> Earlier posts:
> https://lists.osgeo.org/pipermail/qgis-developer/2018-October/054828.html
> [*] https://lists.osgeo.org/pipermail/qgis-developer/2018-October/054829.html
> Related fora:
> - https://gis.stackexchange.com/a/173536/5256
> - https://gis.stackexchange.com/a/223770/5256
> - https://gis.stackexchange.com/a/176723/5256
> - https://gis.stackexchange.com/a/294157/5256
> --
> Nikos Alexandris | Remote Sensing & Geomatics
> GPG Key Fingerprint 6F9D4506F3CA28380974D31A9053534B693C4FB3
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