[OGR provider] Improve detection of layer geometry type

When a OGR layer is of geometry type "unknown", we use the geometry of the first feature to guess the geometry type. But if this feature has no geometry, then we assume that we have no geometry for the whole layer. This is a bit extreme. Let us allow to probe a few features before giving up. Fixes #15065
qgis · Jun 18, 2016 · 3b65568 · nyalldawson · Jun 27, 2016 · rouault
1 parent 7b7c377
commit 3b65568
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Showing 2 changed files with 26 additions and 12 deletions.
diff --git a/src/providers/ogr/qgsogrprovider.cpp b/src/providers/ogr/qgsogrprovider.cpp
@@ -706,23 +706,26 @@ OGRwkbGeometryType QgsOgrProvider::getOgrGeomType( OGRLayerH ogrLayer )
 
     // Some ogr drivers (e.g. GML) are not able to determine the geometry type of a layer like this.
     // In such cases, we use virtual sublayers for each geometry if the layer contains
-    // multiple geometries (see subLayers) otherwise we guess geometry type from first feature
+    // multiple geometries (see subLayers) otherwise we guess geometry type from the first
+    // feature that has a geometry (limit us to a few features, not the whole layer)
     if ( geomType == wkbUnknown )
     {
+      geomType = wkbNone;
       OGR_L_ResetReading( ogrLayer );
-      OGRFeatureH firstFeature = OGR_L_GetNextFeature( ogrLayer );
-      if ( firstFeature )
+      for ( int i = 0; i < 10; i++ )
       {
-        OGRGeometryH firstGeometry = OGR_F_GetGeometryRef( firstFeature );
-        if ( firstGeometry )
-        {
-          geomType = OGR_G_GetGeometryType( firstGeometry );
-        }
-        else
+        OGRFeatureH nextFeature = OGR_L_GetNextFeature( ogrLayer );
+        if ( !nextFeature )
+          break;
+
+        OGRGeometryH geometry = OGR_F_GetGeometryRef( nextFeature );
+        if ( geometry )
         {
-          geomType = wkbNone;
+          geomType = OGR_G_GetGeometryType( geometry );
         }
-        OGR_F_Destroy( firstFeature );
+        OGR_F_Destroy( nextFeature );
+        if ( geomType != wkbNone )
+          break;
       }
       OGR_L_ResetReading( ogrLayer );
     }

diff --git a/tests/src/python/test_provider_ogr.py b/tests/src/python/test_provider_ogr.py
@@ -16,7 +16,7 @@
 import shutil
 import tempfile
 
-from qgis.core import QgsVectorLayer, QgsVectorDataProvider
+from qgis.core import QgsVectorLayer, QgsVectorDataProvider, QgsWKBTypes
 from qgis.testing import (
     start_app,
     unittest
@@ -66,6 +66,17 @@ def testUpdateMode(self):
         self.assertTrue(vl.dataProvider().leaveUpdateMode())
         self.assertEqual(vl.dataProvider().property("_debug_open_mode"), "read-write")
 
+    def testGeometryTypeKnownAtSecondFeature(self):
+
+        datasource = os.path.join(self.basetestpath, 'testGeometryTypeKnownAtSecondFeature.csv')
+        with open(datasource, 'wt') as f:
+            f.write('id,WKT\n')
+            f.write('1,\n')
+            f.write('2,POINT(2 49)\n')
+
+        vl = QgsVectorLayer(u'{}|layerid=0'.format(datasource), u'test', u'ogr')
+        self.assertTrue(vl.isValid())
+        self.assertEqual(vl.wkbType(), QgsWKBTypes.Point)
 
 if __name__ == '__main__':
     unittest.main()