PG: accept duplicated fields for query layers

Fixes #38976
qgis · Sep 23, 2020 · dd64c6d · dd64c6d
1 parent 9880a75
commit dd64c6d
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Showing 2 changed files with 31 additions and 1 deletion.
diff --git a/src/providers/postgres/qgspostgresprovider.cpp b/src/providers/postgres/qgspostgresprovider.cpp
@@ -1175,11 +1175,24 @@ bool QgsPostgresProvider::loadFields()
     if ( fields.contains( fieldName ) )
     {
       QgsMessageLog::logMessage( tr( "Duplicate field %1 found\n" ).arg( fieldName ), tr( "PostGIS" ) );
-      // In case of read-only query layers we can safely ignore the issue
+      // In case of read-only query layers we can safely ignore the issue and rename the duplicated field
       if ( ! mIsQuery )
       {
         return false;
       }
+      else
+      {
+        unsigned short int i = 1;
+        while ( i < std::numeric_limits<unsigned short int>::max() )
+        {
+          const QString newName { QStringLiteral( "%1 (%2)" ).arg( fieldName ).arg( ++i ) };
+          if ( ! fields.contains( newName ) )
+          {
+            fieldName = newName;
+            break;
+          }
+        }
+      }
     }
 
     fields << fieldName;

diff --git a/tests/src/python/test_provider_postgres.py b/tests/src/python/test_provider_postgres.py
@@ -3021,6 +3021,23 @@ def testTrustFlag(self):
         vl = p.mapLayersByName('testTrustFlag')[0]
         self.assertTrue(vl.isValid())
 
+    def testQueryLayerDuplicatedFields(self):
+        """Test that duplicated fields from a query layer are returned"""
+
+        def _get_layer(sql):
+            return QgsVectorLayer(
+                self.dbconn +
+                ' sslmode=disable key=\'__rid__\' table=\'(SELECT row_number() OVER () AS __rid__, * FROM (' + sql + ') as foo)\'  sql=',
+                'test', 'postgres')
+
+        l = _get_layer('SELECT 1, 2')
+        self.assertEqual(l.fields().count(), 3)
+        self.assertEqual([f.name() for f in l.fields()], ['__rid__', '?column?', '?column? (2)'])
+
+        l = _get_layer('SELECT 1 as id, 2 as id')
+        self.assertEqual(l.fields().count(), 3)
+        self.assertEqual([f.name() for f in l.fields()], ['__rid__', 'id', 'id (2)'])
+
 
 if __name__ == '__main__':
     unittest.main()