[OGR provider] Make createEmptyLayer() work properly on GeoPackage wh…

…en creating/overwrite a new database (fixes #20040)

src/providers/ogr/qgsogrprovider.cpp

@@ -299,11 +299,13 @@ QgsVectorLayerExporter::ExportError QgsOgrProvider::createEmptyLayer( const QStr
     }
   }
 
+  QString newLayerName( layerName );
   std::unique_ptr< QgsVectorFileWriter > writer = qgis::make_unique< QgsVectorFileWriter >(
         uri, encoding, fields, wkbType,
         srs, driverName, dsOptions, layerOptions, nullptr,
         QgsVectorFileWriter::NoSymbology, nullptr,
-        layerName, action );
+        layerName, action, &newLayerName );
+  layerName = newLayerName;
 
   QgsVectorFileWriter::WriterError error = writer->hasError();
   if ( error )

tests/src/python/test_provider_ogr_gpkg.py

@@ -466,27 +466,24 @@ def testSimulatedDBManagerImport(self):
         uri = 'point?field=f1:int'
         uri += '&field=f2:double(6,4)'
         uri += '&field=f3:string(20)'
-        lyr = QgsVectorLayer(uri, "x", "memory")
-        self.assertTrue(lyr.isValid())
-        f = QgsFeature(lyr.fields())
+        mem_lyr = QgsVectorLayer(uri, "x", "memory")
+        self.assertTrue(mem_lyr.isValid())
+        f = QgsFeature(mem_lyr.fields())
         f['f1'] = 1
         f['f2'] = 123.456
         f['f3'] = '12345678.90123456789'
-        f2 = QgsFeature(lyr.fields())
+        f2 = QgsFeature(mem_lyr.fields())
         f2['f1'] = 2
-        lyr.dataProvider().addFeatures([f, f2])
+        mem_lyr.dataProvider().addFeatures([f, f2])
 
+        # Test creating new DB
         tmpfile = os.path.join(self.basetestpath, 'testSimulatedDBManagerImport.gpkg')
-        ds = ogr.GetDriverByName('GPKG').CreateDataSource(tmpfile)
-        ds = None
         options = {}
-        options['update'] = True
         options['driverName'] = 'GPKG'
-        options['layerName'] = 'my_out_table'
-        err = QgsVectorLayerExporter.exportLayer(lyr, tmpfile, "ogr", lyr.crs(), False, options)
+        err = QgsVectorLayerExporter.exportLayer(mem_lyr, tmpfile, "ogr", mem_lyr.crs(), False, options)
         self.assertEqual(err[0], QgsVectorLayerExporter.NoError,
                          'unexpected import error {0}'.format(err))
-        lyr = QgsVectorLayer(tmpfile + "|layername=my_out_table", "y", "ogr")
+        lyr = QgsVectorLayer(tmpfile, "y", "ogr")
         self.assertTrue(lyr.isValid())
         features = lyr.getFeatures()
         f = next(features)
@@ -496,26 +493,56 @@ def testSimulatedDBManagerImport(self):
         f = next(features)
         self.assertEqual(f['f1'], 2)
         features = None
+        del lyr
+
+        # Test updating existing DB, by adding a new layer
+        mem_lyr = QgsVectorLayer(uri, "x", "memory")
+        self.assertTrue(mem_lyr.isValid())
+        f = QgsFeature(mem_lyr.fields())
+        f['f1'] = 1
+        f['f2'] = 2
+        mem_lyr.dataProvider().addFeatures([f])
+
+        options = {}
+        options['update'] = True
+        options['driverName'] = 'GPKG'
+        options['layerName'] = 'my_out_table'
+        err = QgsVectorLayerExporter.exportLayer(mem_lyr, tmpfile, "ogr", mem_lyr.crs(), False, options)
+        self.assertEqual(err[0], QgsVectorLayerExporter.NoError,
+                         'unexpected import error {0}'.format(err))
+        lyr = QgsVectorLayer(tmpfile + "|layername=my_out_table", "y", "ogr")
+        self.assertTrue(lyr.isValid())
+        features = lyr.getFeatures()
+        f = next(features)
+        self.assertEqual(f['f1'], 1)
+        self.assertEqual(f['f2'], 2)
+        features = None
+        del lyr
 
         # Test overwriting without overwrite option
-        err = QgsVectorLayerExporter.exportLayer(lyr, tmpfile, "ogr", lyr.crs(), False, options)
+        err = QgsVectorLayerExporter.exportLayer(mem_lyr, tmpfile, "ogr", mem_lyr.crs(), False, options)
         self.assertEqual(err[0], QgsVectorLayerExporter.ErrCreateDataSource)
 
-        # Test overwriting
-        lyr = QgsVectorLayer(uri, "x", "memory")
-        self.assertTrue(lyr.isValid())
-        f = QgsFeature(lyr.fields())
+        # Test overwriting, without specifying a layer name
+        mem_lyr = QgsVectorLayer(uri, "x", "memory")
+        self.assertTrue(mem_lyr.isValid())
+        f = QgsFeature(mem_lyr.fields())
         f['f1'] = 3
-        lyr.dataProvider().addFeatures([f])
+        f['f2'] = 4
+        mem_lyr.dataProvider().addFeatures([f])
+
+        options = {}
+        options['driverName'] = 'GPKG'
         options['overwrite'] = True
-        err = QgsVectorLayerExporter.exportLayer(lyr, tmpfile, "ogr", lyr.crs(), False, options)
+        err = QgsVectorLayerExporter.exportLayer(mem_lyr, tmpfile, "ogr", mem_lyr.crs(), False, options)
         self.assertEqual(err[0], QgsVectorLayerExporter.NoError,
                          'unexpected import error {0}'.format(err))
-        lyr = QgsVectorLayer(tmpfile + "|layername=my_out_table", "y", "ogr")
+        lyr = QgsVectorLayer(tmpfile, "y", "ogr")
         self.assertTrue(lyr.isValid())
         features = lyr.getFeatures()
         f = next(features)
         self.assertEqual(f['f1'], 3)
+        self.assertEqual(f['f2'], 4)
         features = None
 
     def testExportLayerToExistingDatabase(self):