[QGIS-Developer] How to specify GDAL driver to use for Processing INPUT?

[Johannes Kröger (WhereGroup)]

Howdy!

Trying to debug some issues with the QGIS GML Application Schema Toolbox 
plugin 
(https://github.com/BRGM/gml_application_schema_toolbox/issues/263) I 
realised that I have no idea how to specify a specific driver to be used 
by GDAL/OGR when running a tool via Processing? Or if it is even 
possible at all. GDAL/OGR calls them prefixes to the connection string, 
e.g. https://gdal.org/drivers/vector/gmlas.html#opening-syntax

E. g. this would use whatever driver GDAL/OGR decides to use for the GML 
file and works:

     processing.run("gdal:convertformat", 
{'INPUT':'/tmp/tmpssu67zi9.gml','OUTPUT':'/tmp/test.shp'})

But I need to make it use its GMLAS driver. Trying to add the prefix 
results in a crash because of the file not being found:

     processing.run("gdal:convertformat", 
{'INPUT':'GMLAS:/tmp/tmpssu67zi9.gml','OUTPUT':'/tmp/test2.shp'})

     Traceback (most recent call last):
       File "/usr/lib/python3.10/code.py", line 90, in runcode
         exec(code, self.locals)
       File "<input>", line 1, in <module>
       File 
"/usr/share/qgis/python/plugins/processing/tools/general.py", line 108, 
in run
         return Processing.runAlgorithm(algOrName, parameters, onFinish, 
feedback, context)
       File 
"/usr/share/qgis/python/plugins/processing/core/Processing.py", line 
181, in runAlgorithm
         raise QgsProcessingException(msg)
     _core.QgsProcessingException: Unable to execute algorithm
     Could not load source layer for INPUT: GMLAS:/tmp/tmpssu67zi9.gml 
not found

For this specific tool, the docs say that INPUT shall be "[vector: any]" 
but passing simple paths works fine in pretty much all processing tools. 
https://docs.qgis.org/3.28/en/docs/user_manual/processing_algs/gdal/vectorconversion.html?highlight=convertformat

Is there any way to do this?

PS: Crossposted to 
https://gis.stackexchange.com/questions/451645/how-to-specify-gdal-driver-to-use-for-processing-input

Cheers, Hannes

-- 
Johannes Kröger / GIS-Entwickler/-Berater

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