0

I'm trying to reassign crs when writing snippets to do as described, combining with pre-existing Python code. I couldn't find the way to append to gpkg without saving the file onto local storage and then reading again.

What I'm describing here is something like:

import glob
import os

group = QgsProject.instance().layerTreeRoot().findGroup('nameOfTheGroup')
DIR = 'Users/name/Desktop/tmp/'


for child in group.children():
    lyr = child.layer()
    # I can only export the layer onto local
    QgsVectorFileWriter.writeAsVectorFormat(
        lyr, DIR+lyr.name(), "utf-8", 
        QgsCoordinateReferenceSystem(4326),  # Reassigning CRS here
        "ESRI Shapefile"
        )


os.chdir(DIR)


reload from local


lyr_dir = glob.glob('*.shp')
lyrs = QgsVectorlayer(lyr, os.path.basename(), 'ogr')


and save it to gpkg


params = {'LAYERS': lyrs,
          'OUTPUT': 'output.gpkg',
          'OVERWRITE': False,  # Important!
          'SAVE_STYLES': False,
          'SAVE_METADATA': False,
          'SELECTED_FEATURES_ONLY': False}


processing.run("native:package", params)

Well technically it does work, but it has so much redundant part! I know it could go around with ogr2ogr with only 2 lines of code:

>>> ogr2ogr -f GPKG assignedCRS.gpkg -t_srs "EPSG:4326" input.gpkg
>>> ogrmerge.py -f GPKG -o output.gpkg assignedCRS.gpkg

BUT this has to be done in terminal.

How do I do this with PyQGIS only?

I might need to add extra functions other than assigning crs and to fully done without Python console has more readability and in one place.

PolyGeo
  • 65,136
  • 29
  • 109
  • 338
Cookie
  • 355
  • 1
  • 7
  • I don't understand why you do this on the command line ogrmerge.py -f GPKG -o output.gpkg assignedCRS.gpkg. Is something missing from the command? As it stands now it only creates a new copy from assignedCRS.gpkg. – user30184 Oct 22 '22 at 10:57
  • Yeah thats my mistake. I was doing this with *.shp. sorry bout that – Cookie Oct 23 '22 at 14:28

1 Answers1

1

Wouldn't something like this work, if all you need is a list of layers:

group = QgsProject.instance().layerTreeRoot().findGroup('nameOfTheGroup')
lyrs = []
for child in group.children():
    lyrs.append(child.layer())

and save it to gpkg


params = {'LAYERS': lyrs,
          'OUTPUT': 'output.gpkg',
          'OVERWRITE': False,  # Important!
          'SAVE_STYLES': False,
          'SAVE_METADATA': False,
          'SELECTED_FEATURES_ONLY': False}


processing.run("native:package", params)
Ian Turton
  • 81,417
  • 6
  • 84
  • 185