'Opening of data source in update mode failed (OGR error: )' error when adding layer to GeoPackage using PyQGIS

Question

While running the following code:

from qgis.utils import iface
from qgis.core import QgsVectorFileWriter

canvas = iface.mapCanvas()
layer = canvas.currentLayer()
print(layer.name())

options = QgsVectorFileWriter.SaveVectorOptions()
options.actionOnExistingFile = QgsVectorFileWriter.CreateOrOverwriteLayer

#options.layerName = "_".join(layer.name().split(' '))
writer = QgsVectorFileWriter.writeAsVectorFormat(layer, "C:/Users/ilyasse2.0/Documents/SQRLAND/hh.gpkg", options)
print(writer)

I got this error:

(2, 'Opening of data source in update mode failed (OGR error: )')

The layer is created by with:

from qgis.core import QgsVectorLayer

layer = QgsVectorLayer("Point", 'layerName', "memory")

I tried to use this solution: Adding layers to GeoPackage using PyQGIS but it is not working for me.

Answer 1

If you want to create a GeoPackage or if you already have a GeoPackage with layers in it and want to add another layer to it you can use this example where I create a memory layer with a process (extent of a layer) and then add it to the GeoPackage:

import processing
from os.path import abspath, isfile, join
from qgis.utils import iface
from qgis.core import QgsProject, QgsVectorFileWriter

path = abspath("path/to/layer")
gpgk_name = 'test.gpkg'
gpkg_path = join(path, gpgk_name) # your geopackage

polygon_layer = iface.activeLayer()

extent = processing.run("qgis:polygonfromlayerextent",{
                                 'INPUT': polygon_layer,
                                 'ROUND_TO': 0,
                                 'OUTPUT': 'TEMPORARY_OUTPUT'
                                 })
layer = extent['OUTPUT'] # your memory layer

context = QgsProject.instance().transformContext()
options = QgsVectorFileWriter.SaveVectorOptions()

if isfile(gpkg_path):
    options.actionOnExistingFile = QgsVectorFileWriter.CreateOrOverwriteLayer
options.layerName = layer.name()
options.fileEncoding = layer.dataProvider().encoding()
options.driverName = "GPKG"

QgsVectorFileWriter.writeAsVectorFormatV3(layer, gpkg_path, context, options)

At the begining I had this, a GeoPackage with three layers:

After creating the extent as a memory layer and add it to the GeoPackage I have this:

If you want to overwrite an existing GeoPackage you need to delete this condition:

from os.path import isfile

if isfile(gpkg_path):
    options.actionOnExistingFile = QgsVectorFileWriter.CreateOrOverwriteLayer

Answer 2

These PyQGIS solutions seem very convoluted. You can just use GeoPandas to write a new layer to an existing GeoPackage like this:

import geopandas as gpd

gdf = gpd.read_file(#whatever your source is#)
gpkg_file = 'name.gpkg'
new_layer = 'newlayer'
gdf.to_file(gpkg_file, layer=new_layer, driver="GPKG")