[Qgis-user] Pyqgis how to append existing gpkg layer

[Anne B. Nilsen]

I'm not a pyQGIS-expert, but with help from gis.stackechange.com I have managed to create an empty geopackage file and then adding several layers to it with this code:
...
gpkg_reg = "karplanteregistrering.gpkg"                   # the NEW gpkg to be created
if os.path.exists(gpkg_reg):                              # If gpkg-file already exists, delete it
    os.remove(gpkg_reg)
...
# https://gis.stackexchange.com/questions/417916/creating-empty-layers-in-a-geopackage-using-pyqgis?noredirect=1&lq=1
def create_blank_gpkg_layer(gpkg_path: str, layer_name: str, geometry: int,
                            crs: str, fields: QgsFields, append: bool = False
                            ) -> bool:
    # To add a layer to an existing GPKG file, pass 'append' as True
    options = QgsVectorFileWriter.SaveVectorOptions()
    options.driverName = "GPKG"
    options.layerName = layer_name
    if append:
        options.actionOnExistingFile = QgsVectorFileWriter.CreateOrOverwriteLayer
        writer = QgsVectorFileWriter.create(
        gpkg_path,
        fields,
        geometry,
        QgsCoordinateReferenceSystem(crs),
        QgsCoordinateTransformContext(),
        options)
    del writer
    return True
...
# Layer 1 oversikt - creating an empty layer with attributes read from a csv-file
f = open("./egenskaper/egenskaper_oversikt.csv",'r') # open file
f.readline()  # read the first line of the file (the "metadata"/heading)
layer_name = "oversikt"              # set layer name
print('creates layer', layer_name)   # print layer name
geom = QgsWkbTypes.PointZ            # geometrytype
crs = 'epsg:25832'                   # coordinate system
fields = QgsFields()
for line in f:                       # Read attrubutes from csv-file
     r = {}
     r = line.split(';')  # 0 navn, 1 QVariant-type, 2 lengde og 3 presisjon
     fname = r[0]
     l = int(r[2])
     p = int(r[3])
     try:
          fields.append(QgsField(fname,set_variant(r[1]),'',l,p))  # add field to layer
     except:
          print("Noe gikk galt - får ikke laget egenskaper fra " +str(f))
f.close()  # close file
create_blank_gpkg_layer(gpkg_reg, layer_name, geom, crs, fields)  # Do NOT include True when the FIRST layer is created

# Layer 2 arter (to be added to the same new gpkg-file just created above)
f = open("./egenskaper/egenskaper_arter.csv",'r') # open file
f.readline()
layer_name = "arter"
print('creates layer', layer_name)   # print layer name
geom = QgsWkbTypes.PointZ            # geometrytype
crs = 'epsg:25832'                   # coordinate system
fields = QgsFields()
for line in f:                       # Read attrubutes from csv-file
     r = {}
     r = line.split(';')  # 0 navn, 1 QVariant-type, 2 lengde og 3 presisjon
     fname = r[0]
     l = int(r[2])
     p = int(r[3])
     try:
          fields.append(QgsField(fname,set_variant(r[1]),'',l,p))  # add field to layer
     except:
          print("Noe gikk galt - får ikke laget egenskaper fra " +str(f))
f.close()  # close file
create_blank_gpkg_layer(gpkg_reg, layer_name, geom, crs, fields, True)  # Include True to add a new layer to the SAME gpkg-file
...

Note the difference in the use of True and not when calling create_blank_gpk_layer().
Perhaps something similar may be the solution to your problem.

Kind regards
Anne


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