Merge pull request #4604 from boundlessgeo/postgis_merge_features_port3_fix#15741

Fix Postgis Merge selected features regression (fix #15741)

Author: alexbruy

src/core/qgsvectordataprovider.h

@@ -56,6 +56,7 @@ class CORE_EXPORT QgsVectorDataProvider : public QgsDataProvider, public QgsFeat
     Q_OBJECT
 
     friend class QgsTransaction;
+    friend class QgsVectorLayerEditBuffer;
 
   public:
 

src/core/qgsvectorlayereditbuffer.cpp

@@ -310,6 +310,35 @@ bool QgsVectorLayerEditBuffer::commitChanges( QStringList &commitErrors )
   // no                 yes                   => changeAttributeValues
   // yes                yes                   => changeFeatures
 
+  // to fix https://issues.qgis.org/issues/15741
+  // first of all check if feature to add is compatible with provider type
+  // this check have to be done before all checks to avoid to clear internal
+  // buffer if some of next steps success.
+  if ( success && !mAddedFeatures.isEmpty() )
+  {
+    if ( cap & QgsVectorDataProvider::AddFeatures )
+    {
+      for ( QgsFeature f : mAddedFeatures )
+      {
+        if ( ( ! f.hasGeometry() ) ||
+             ( f.geometry().wkbType() == provider->wkbType() ) )
+          continue;
+
+        if ( provider->convertToProviderType( f.geometry() ).isNull() )
+        {
+          commitErrors << tr( "ERROR: %n feature(s) not added - geometry type is not compatible with the current layer.", "not added features count", mAddedFeatures.size() );
+          success = false;
+          break;
+        }
+      }
+    }
+    else
+    {
+      commitErrors << tr( "ERROR: %n feature(s) not added - provider doesn't support adding features.", "not added features count", mAddedFeatures.size() );
+      success = false;
+    }
+  }
+
   //
   // update geometries
   //

tests/src/python/test_qgsvectorlayereditbuffer.py

@@ -44,6 +44,13 @@ def createLayerWithOnePoint():
     return layer
 
 
+def createEmptyLinestringLayer():
+    layer = QgsVectorLayer("Linestring?field=fldtxt:string&field=fldint:integer",
+                           "addfeat", "memory")
+    assert layer.isValid()
+    return layer
+
+
 class TestQgsVectorLayerEditBuffer(unittest.TestCase):
 
     def testAddFeatures(self):
@@ -78,6 +85,27 @@ def testAddFeatures(self):
         self.assertTrue(layer.editBuffer().isFeatureAdded(new_feature_ids[0]))
         self.assertTrue(layer.editBuffer().isFeatureAdded(new_feature_ids[1]))
 
+        # check if error in case adding not adaptable geometry
+        # eg. a Multiline in a Line
+        layer = createEmptyLinestringLayer()
+        self.assertTrue(layer.startEditing())
+
+        self.assertEqual(layer.editBuffer().addedFeatures(), {})
+        self.assertFalse(layer.editBuffer().isFeatureAdded(1))
+        self.assertFalse(layer.editBuffer().isFeatureAdded(3))
+
+        # add a features with a multi line geometry of not touched lines =>
+        # cannot be forced to be linestring
+        multiline = [
+            [QgsPointXY(1, 1), QgsPointXY(2, 2)],
+            [QgsPointXY(3, 3), QgsPointXY(4, 4)],
+        ]
+        f1 = QgsFeature(layer.fields(), 1)
+        f1.setGeometry(QgsGeometry.fromMultiPolyline(multiline))
+        f1.setAttributes(["test", 123])
+        self.assertTrue(layer.addFeatures([f1]))
+        self.assertFalse(layer.commitChanges())
+
     def testAddMultipleFeatures(self):
         # test adding multiple features to an edit buffer
         layer = createEmptyLayer()