[OGR] Add workaround for OGRSQL not recognizing the column name returned by OGR_L_GetFIDColumn

Author: manisandro

src/providers/ogr/qgsogrprovider.cpp

@@ -3537,26 +3537,51 @@ OGRLayerH QgsOgrProviderUtils::setSubsetString( OGRLayerH layer, GDALDatasetH ds
       layerName = encoding->fromUnicode( modifiedLayerName );
     }
   }
-  QByteArray sql;
+  OGRLayerH subsetLayer = 0;
   if ( subsetString.startsWith( QLatin1String( "SELECT " ), Qt::CaseInsensitive ) )
-    sql = encoding->fromUnicode( subsetString );
+  {
+    QByteArray sql = encoding->fromUnicode( subsetString );
+
+    QgsDebugMsg( QString( "SQL: %1" ).arg( encoding->toUnicode( sql ) ) );
+    subsetLayer = GDALDatasetExecuteSQL( ds, sql.constData(), nullptr, nullptr );
+  }
   else
   {
+    QByteArray sqlPart1 = "SELECT ";
+    QByteArray sqlPart3 = "* FROM " + quotedIdentifier( layerName, mGDALDriverName )
+                          + " WHERE " + encoding->fromUnicode( subsetString );
+
+    origFidAddAttempted = true;
+
     QByteArray fidColumn = OGR_L_GetFIDColumn( layer );
+    // Fallback to FID if OGR_L_GetFIDColumn returns nothing
+    if ( fidColumn.isEmpty() )
+    {
+      fidColumn = "FID";
+    }
+
+    QByteArray sql = sqlPart1 + fidColumn + " as orig_ogc_fid, " + sqlPart3;
+    QgsDebugMsg( QString( "SQL: %1" ).arg( encoding->toUnicode( sql ) ) );
+    subsetLayer = GDALDatasetExecuteSQL( ds, sql.constData(), nullptr, nullptr );
 
-    sql = QByteArray( "SELECT " );
-    if ( !fidColumn.isEmpty() )
+    // See https://lists.osgeo.org/pipermail/qgis-developer/2017-September/049802.html
+    // If execute SQL fails because it did not find the fidColumn, retry with hardcoded FID
+    if ( !subsetLayer )
     {
-      sql += fidColumn + " as orig_ogc_fid, ";
-      origFidAddAttempted = true;
+      QByteArray sql = sqlPart1 + "FID as orig_ogc_fid, " + sqlPart3;
+      QgsDebugMsg( QString( "SQL: %1" ).arg( encoding->toUnicode( sql ) ) );
+      subsetLayer = GDALDatasetExecuteSQL( ds, sql.constData(), nullptr, nullptr );
+    }
+    // If that also fails, just continue without the orig_ogc_fid
+    if ( !subsetLayer )
+    {
+      QByteArray sql = sqlPart1 + sqlPart3;
+      QgsDebugMsg( QString( "SQL: %1" ).arg( encoding->toUnicode( sql ) ) );
+      subsetLayer = GDALDatasetExecuteSQL( ds, sql.constData(), nullptr, nullptr );
+      origFidAddAttempted = false;
     }
-    sql += "* FROM " + quotedIdentifier( layerName, mGDALDriverName );
-    sql += " WHERE " + encoding->fromUnicode( subsetString );
   }
 
-  QgsDebugMsg( QString( "SQL: %1" ).arg( encoding->toUnicode( sql ) ) );
-  OGRLayerH subsetLayer = GDALDatasetExecuteSQL( ds, sql.constData(), nullptr, nullptr );
-
   // Check if first column is orig_ogc_fid
   if ( origFidAddAttempted && subsetLayer )
   {

tests/src/python/test_provider_ogr.py

@@ -17,7 +17,7 @@
 import sys
 import tempfile
 
-from qgis.core import QgsVectorLayer, QgsVectorDataProvider, QgsWkbTypes
+from qgis.core import QgsVectorLayer, QgsVectorDataProvider, QgsWkbTypes, QgsFeature
 from qgis.testing import (
     start_app,
     unittest
@@ -238,6 +238,23 @@ def testGeometryCollection(self):
         os.unlink(datasource)
         self.assertFalse(os.path.exists(datasource))
 
+    def testGdb(self):
+        """ Test opening a GDB database layer"""
+        gdb_path = os.path.join(unitTestDataPath(), 'test_gdb.gdb')
+        for i in range(3):
+            l = QgsVectorLayer(gdb_path + '|layerid=' + str(i), 'test', 'ogr')
+            self.assertTrue(l.isValid())
+
+    def testGdbFilter(self):
+        """ Test opening a GDB database layer with filter"""
+        gdb_path = os.path.join(unitTestDataPath(), 'test_gdb.gdb')
+        l = QgsVectorLayer(gdb_path + '|layerid=1|subset="text" = \'shape 2\'', 'test', 'ogr')
+        self.assertTrue(l.isValid())
+        it = l.getFeatures()
+        f = QgsFeature()
+        while it.nextFeature(f):
+            self.assertTrue(f.attribute("text") == "shape 2")
+
 
 if __name__ == '__main__':
     unittest.main()