Named algorithm outputs in modeler fail when used as inputs #27200
Labels
Bug
Either a bug report, or a bug fix. Let's hope for the latter!
High Priority
Processing
Relating to QGIS Processing framework or individual Processing algorithms
Regression
Something which used to work, but doesn't anymore
Author Name: Rudi von Staden (@rudivs)
Original Redmine Issue: 19372
Affected QGIS version: 3.2
Redmine category:processing/modeller
Using the modeler in QGIS 3.2, if you give a name to the output of an algorithm, you can't use that output as input for a subsequent algorithm. Trying to do so results in a processing error (
Could not load source layer for INPUT: invalid value
). I have attached a test project with some data and a model to demonstrate the issue. Included is a folder with an equivalent project in QGIS 2.18 showing that the same model worked in previous versions.The model runs two parallel processes which are identical (polygonize raster then extract by attribute) except the second names the output of the polygonize step before using it in the extract step. I am fairly sure that this is not an issue with the test algorithms used here, but more broadly with the mapping of input and output parameters in models. You can see in the model log below that the first 'extract by attribute' algorithm was able to find the input file (standard named
OUTPUT.shp
) but the second time the algorithm is executed it has an empty INPUT parameter. This is probably because the output of the previous step results in a file namedgdal_polygonize_2_DEM_vector.shp
, notOUTPUT.shp
as usual.I am not sure where the mapping of output and input names happens in the processing code (and whether it's executed in c++ or Python). If it's in Python I'd be happy to look into it if someone can tell me which class or file to start the investigation.
The text was updated successfully, but these errors were encountered: