[bugfix] Vector file writer: also check for layername before giving up

while (over)writing gpkg &C from vector file writer

With tests

Fixes #19611 - Cannot save selected features back to the same GeoPackage

Author: elpaso

src/core/qgsvectorfilewriter.cpp

@@ -2550,16 +2550,35 @@ QgsVectorFileWriter::WriterError QgsVectorFileWriter::writeAsVectorFormat( Prepa
   int lastProgressReport = 0;
   long total = details.featureCount;
 
+  // Special rules for OGR layers
   if ( details.providerType == QLatin1String( "ogr" ) && !details.dataSourceUri.isEmpty() )
   {
     QStringList theURIParts = details.dataSourceUri.split( '|' );
     QString srcFileName = theURIParts[0];
+    QgsStringMap srcUriParams;
+    if ( theURIParts.length() > 0 )
+    {
+      for ( int i = 1; i < theURIParts.length(); ++i )
+      {
+        QStringList parts( theURIParts[i].split( '=' ) );
+        if ( parts.length() == 2 )
+          srcUriParams[parts[0]] = parts[1];
+      }
+    }
 
     if ( QFile::exists( srcFileName ) && QFileInfo( fileName ).canonicalFilePath() == QFileInfo( srcFileName ).canonicalFilePath() )
     {
-      if ( errorMessage )
-        *errorMessage = QObject::tr( "Cannot overwrite a OGR layer in place" );
-      return ErrCreateDataSource;
+      // Check the layer name too if it's a GPKG/SpatiaLite/SQLite OGR driver
+      QgsDataSourceUri uri( details.dataSourceUri );
+      if ( !( ( options.driverName == QLatin1String( "GPKG" ) ||
+                options.driverName == QLatin1String( "SpatiaLite" ) ||
+                options.driverName == QLatin1String( "SQLite" ) ) &&
+              options.layerName != srcUriParams["layername"] ) )
+      {
+        if ( errorMessage )
+          *errorMessage = QObject::tr( "Cannot overwrite a OGR layer in place" );
+        return ErrCreateDataSource;
+      }
     }
 
     // Shapefiles might contain multi types although wkbType() only reports singles

tests/src/python/test_qgsvectorfilewriter.py

@@ -32,6 +32,7 @@
                        )
 from qgis.PyQt.QtCore import QDate, QTime, QDateTime, QVariant, QDir
 import os
+import tempfile
 import osgeo.gdal  # NOQA
 from osgeo import gdal, ogr
 from qgis.testing import start_app, unittest
@@ -898,6 +899,46 @@ def testSupportsFeatureStyles(self):
         self.assertTrue(QgsVectorFileWriter.supportsFeatureStyles('MapInfo File'))
         self.assertTrue(QgsVectorFileWriter.supportsFeatureStyles('MapInfo MIF'))
 
+    def testOverwriteGPKG(self):
+        """Test that overwriting the same origin GPKG file works only if the layername is different"""
+
+        # Prepare test data
+        ml = QgsVectorLayer('Point?field=firstfield:int&field=secondfield:int', 'test', 'memory')
+        provider = ml.dataProvider()
+        ft = QgsFeature()
+        ft.setAttributes([4, -10])
+        provider.addFeatures([ft])
+        filehandle, filename = tempfile.mkstemp('.gpkg')
+
+        options = QgsVectorFileWriter.SaveVectorOptions()
+        options.driverName = 'GPKG'
+        options.layerName = 'test'
+        write_result, error_message = QgsVectorFileWriter.writeAsVectorFormat(
+            ml,
+            filename,
+            options)
+        self.assertEqual(write_result, QgsVectorFileWriter.NoError, error_message)
+
+        # Real test
+        vl = QgsVectorLayer("%s|layername=test" % filename, 'src_test', 'ogr')
+        self.assertTrue(vl.isValid())
+        self.assertEqual(vl.featureCount(), 1)
+
+        # This must fail
+        write_result, error_message = QgsVectorFileWriter.writeAsVectorFormat(
+            vl,
+            filename,
+            options)
+        self.assertEqual(write_result, QgsVectorFileWriter.ErrCreateDataSource)
+        self.assertEqual(error_message, 'Cannot overwrite a OGR layer in place')
+
+        options.layerName = 'test2'
+        write_result, error_message = QgsVectorFileWriter.writeAsVectorFormat(
+            vl,
+            filename,
+            options)
+        self.assertEqual(write_result, QgsVectorFileWriter.NoError, error_message)
+
 
 if __name__ == '__main__':
     unittest.main()