Getting the 'memory:' layers after grass7:v.clean processing using PyQGIS?

Question

To repair geometries errors, I'm now trying processing (grass7) using PyQGIS. For one polygon layer (QgsVectorLayer: 'hn_pg'), I wrote the below script and run the grass7:v.clean algorithm. The processing completed without any problems, but the cleaned layer could not appear to the current active layers.

output = processing.runAndLoadResults(
            "grass7:v.clean",
           {'input': hn_pg,
            'type':[0,1,2,3,4,5,6], 
            'tool':[1],   # snap 
            'threshold':0.5,
            '-b':False,
            '-c':False,
            'GRASS_SNAP_TOLERANCE_PARAMETER':1,
            'GRASS_REGION_PARAMETER': "%f, %f, %f, %f"%hn_pg.extent().xMinimum(),hn_pg.extent().xMaximum(), hn_pg.extent().yMinimum(), hn_pg.extent().yMaximum()),
            'GRASS_MIN_AREA_PARAMETER':0.0001,
            'GRASS_OUTPUT_TYPE_PARAMETER':0,
            'output':'memory:',
            'GRASS_VECTOR_DSCO' : '',
            'GRASS_VECTOR_EXPORT_NOCAT' : False,
            'GRASS_VECTOR_LCO' : '',
            'error' : 'memory:'})

QgsProcessingUtils.tempFolder() function provided the path of the completed file(.gpkg) and I also found the outputted file in that file. So, I tried QgsProject.instance().addMapLayer(output['output']) but resulted in no reaction.

How Can I get the cleaned object in Qgis active layers?

Answer 1

Try replacing memory: with TEMPORARY_OUTPUT. The following code works for me which was executed on a polygon .gpkg file:

hn_pg = iface.activeLayer()
output = processing.runAndLoadResults(
            "grass7:v.clean",
            {'input': hn_pg,
            'type':[0,1,2,3,4,5,6], 
            'tool':[1],   # snap 
            'threshold':0.5,
            '-b':False,
            '-c':False,
            'GRASS_SNAP_TOLERANCE_PARAMETER':1,
            'GRASS_REGION_PARAMETER': "%f, %f, %f, %f"%(hn_pg.extent().xMinimum(),hn_pg.extent().xMaximum(), hn_pg.extent().yMinimum(), hn_pg.extent().yMaximum()),
            'GRASS_MIN_AREA_PARAMETER':0.0001,
            'GRASS_OUTPUT_TYPE_PARAMETER':0,
            'output':'TEMPORARY_OUTPUT',
            'GRASS_VECTOR_DSCO' : '',
            'GRASS_VECTOR_EXPORT_NOCAT' : False,
            'GRASS_VECTOR_LCO' : '',
            'error':'TEMPORARY_OUTPUT'})

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Tested on QGIS 3.8.1 on Win 7 64-bit.