QGIS » QGIS Application

Hi,

QgsProcessingParameterNumber doesn't seem to evaluate fields in processing models.

Steps to reproduce

1. Create a new model with an input vector layer
2. Add the "Set M Value" algorithm
3. Use an expression referring an attribute of the input layer.
4. Run

All points will have M Value to 0, as the expression doesn't evaluate correctly.

Notes

- expressions are evaluated, as if you use "3+4" as expression, the M value is set to 7.
- it works as expected outside of the processing modeler both by choosing the field or by setting an expression.

Logs (in a processing model)

Running Set M value [1/1]
Input Parameters:
{ INPUT: 'PointM?crs=EPSG:3460&field=fid:long&field=date%2Ftime:string(255)&field=lat:double&field=long:double&field=hPa:integer&field=cat:integer&field=kts:integer&uid={92a59f27-e18c-482a-a549-f934d0b735b0}', M_VALUE: [cat], OUTPUT: 'memory:' }

Logs (by running the algorithm directly)

Algorithm 'Set M value' starting…
Input parameters:
{ 'INPUT' : 'C:/Users/Olivier/temp/tracks.gpkg|layername=test-EPSG3460', 'M_VALUE' : QgsProperty.fromExpression('"cat"'), 'OUTPUT' : 'memory:' }

Note the difference in the M_VALUE parameter, not sure why I get [cat] there, while my expression is "cat".

I also tried some workarounds, like using attribute( $currentfeature, 'cat' ) instead of cat, but then, the MVALUE is None in the log.