SAGA Tool clip raster by mask layer for QGIS standalone script

Question

In my PyQGIS standalone script I want to use the SAGA Tool "Clip raster by mask layer". I have tried to following.

def clipRaster(self):
    raster = self.getRasterLayer()
    vector = self.getVectorLayer()
    outDir = os.path.join(QgsProject().instance().homePath(), "clip.tiff")
    param = {"input": raster,
             "polygons": vector,
             "output": outDir,
             }
    clip = processing.run('saga:cliprasterwithpolygon', param)
    rlayer = QgsRasterLayer(clip['output'], 'clip')
    QgsProject().instance().addMapLayer(rlayer)

Unfortunately, I get the following error message:

_core.QgsProcessingException: Unable to execute algorithm Could not load source layer for INPUT: no value specified for parameter Traceback (most recent call last): File "C:/Users/Jan/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\gebeude_betroffenheit\Gebeude_Betroffenheit.py", line 292, in run self.clipRaster() File "C:/Users/Jan/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\gebeude_betroffenheit\Gebeude_Betroffenheit.py", line 237, in clipRaster clip = processing.run('saga:cliprasterwithpolygon', param) File "C:/PROGRA~1/QGIS3~1.4/apps/qgis-ltr/./python/plugins\processing\tools\general.py", line 105, in run return Processing.runAlgorithm(algOrName, parameters, onFinish, feedback, context) File "C:/PROGRA~1/QGIS3~1.4/apps/qgis-ltr/./python/plugins\processing\core\Processing.py", line 139, in runAlgorithm raise QgsProcessingException(msg) _core.QgsProcessingException: Unable to execute algorithm Could not load source layer for INPUT: no value specified for Parameter

Hmm it indicates that there is something wrong with the raster layer but the same layer works perfectly fine for another function. Thus, I believe there is something wrong with the "param" variable...

Does anyone see the problem in my code?

I'm using QGIS 3.4

Answer 1

Ok I found the problem. In my outDir, I ordered to save the new raster as .tiff. However SAGA tools save all rasters in .sdat format.

After I changed the name from "clip.tiff" to "clip.sdat" the error message disappeared.