Fix offline editing with gpkg

Up to now, all features were written twice, once with QgsVectorFileWriter, once via addFeature in a subsequent loop. Now it is only done once in a loop, because the loop needs to be done anyway to create the lookup table

Author: m-kuhn

src/core/qgsofflineediting.cpp

@@ -45,6 +45,8 @@
 #include <QFile>
 #include <QMessageBox>
 
+#include <ogr_srs_api.h>
+
 extern "C"
 {
 #include <sqlite3.h>
@@ -630,18 +632,80 @@ QgsVectorLayer *QgsOfflineEditing::copyVectorLayer( QgsVectorLayer *layer, sqlit
     }
     case GPKG:
     {
-      QgsVectorFileWriter::SaveVectorOptions options;
-      options.driverName = QStringLiteral( "GPKG" );
-      options.layerName = tableName;
-      options.actionOnExistingFile = QgsVectorFileWriter::CreateOrOverwriteLayer;
-      options.onlySelectedFeatures = onlySelected;
-
-      QString error;
-      if ( QgsVectorFileWriter::writeAsVectorFormat( layer, offlineDbPath, options, &error ) != QgsVectorFileWriter::NoError )
+      // Set options
+      char **options = nullptr;
+
+      options = CSLSetNameValue( options, "OVERWRITE", "YES" );
+      options = CSLSetNameValue( options, "IDENTIFIER", layer->name().toUtf8().constData() );
+      options = CSLSetNameValue( options, "DESCRIPTION", layer->dataComment().toUtf8().constData() );
+#if 0
+      options = CSLSetNameValue( options, "FID", featureId.toUtf8().constData() );
+#endif
+
+      if ( layer->isSpatial() )
+      {
+        options = CSLSetNameValue( options, "GEOMETRY_COLUMN", "geom" );
+        options = CSLSetNameValue( options, "SPATIAL_INDEX", "YES" );
+      }
+
+      OGRSFDriverH hDriver = nullptr;
+      OGRSpatialReferenceH hSRS = OSRNewSpatialReference( layer->crs().toWkt().toLocal8Bit().data() );
+      gdal::ogr_datasource_unique_ptr hDS( OGROpen( offlineDbPath.toUtf8().constData(), true, &hDriver ) );
+      OGRLayerH hLayer = OGR_DS_CreateLayer( hDS.get(), tableName.toUtf8().constData(), hSRS, static_cast<OGRwkbGeometryType>( layer->wkbType() ), options );
+      CSLDestroy( options );
+      if ( hSRS )
+        OSRRelease( hSRS );
+      if ( !hLayer )
+      {
+        showWarning( tr( "Creation of layer failed (OGR error: %1)" ).arg( QString::fromUtf8( CPLGetLastErrorMsg() ) ) );
+        return nullptr;
+      }
+
+      const QgsFields providerFields = layer->dataProvider()->fields();
+      for ( const auto &field : providerFields )
+      {
+        const QString fieldName( field.name() );
+        const QVariant::Type type = field.type();
+        OGRFieldType ogrType( OFTString );
+        if ( type == QVariant::Int )
+          ogrType = OFTInteger;
+        else if ( type == QVariant::LongLong )
+          ogrType = OFTInteger64;
+        else if ( type == QVariant::Double )
+          ogrType = OFTReal;
+        else if ( type == QVariant::Time )
+          ogrType = OFTTime;
+        else if ( type == QVariant::Date )
+          ogrType = OFTDate;
+        else if ( type == QVariant::DateTime )
+          ogrType = OFTDateTime;
+        else
+          ogrType = OFTString;
+
+        int ogrWidth = field.length();
+
+        gdal::ogr_field_def_unique_ptr fld( OGR_Fld_Create( fieldName.toUtf8().constData(), ogrType ) );
+        OGR_Fld_SetWidth( fld.get(), ogrWidth );
+
+        if ( OGR_L_CreateField( hLayer, fld.get(), true ) != OGRERR_NONE )
+        {
+          showWarning( tr( "Creation of field %1 failed (OGR error: %2)" )
+                       .arg( fieldName, QString::fromUtf8( CPLGetLastErrorMsg() ) ) );
+          return nullptr;
+        }
+      }
+
+      // In GDAL >= 2.0, the driver implements a deferred creation strategy, so
+      // issue a command that will force table creation
+      CPLErrorReset();
+      OGR_L_ResetReading( hLayer );
+      if ( CPLGetLastErrorType() != CE_None )
       {
-        showWarning( tr( "Packaging layer %1 failed: %2" ).arg( layer->name(), error ) );
+        QString msg( tr( "Creation of layer failed (OGR error: %1)" ).arg( QString::fromUtf8( CPLGetLastErrorMsg() ) ) );
+        showWarning( msg );
         return nullptr;
       }
+      hDS.reset();
 
       QString uri = QStringLiteral( "%1|layername=%2" ).arg( offlineDbPath,  tableName );
       newLayer = new QgsVectorLayer( uri, layer->name() + " (offline)", QStringLiteral( "ogr" ) );