Fix cloning a vector layer loses all features if the layer is a memor…

…y layer
qgis · Jul 1, 2019 · 0c6dc87 · 0c6dc87
1 parent e9fbe3a
commit 0c6dc87
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diff --git a/python/core/auto_generated/qgsvectordataprovider.sip.in b/python/core/auto_generated/qgsvectordataprovider.sip.in
@@ -605,6 +605,14 @@ Returns ``True`` if the data source has metadata, ``False`` otherwise.
 :return: ``True`` if data source has metadata, ``False`` otherwise.
 
 .. versionadded:: 3.0
+%End
+
+    virtual void handlePostCloneOperations( QgsVectorDataProvider *source );
+%Docstring
+Handles any post-clone operations required after this vector data provider was cloned
+from the ``source`` provider.
+
+.. versionadded:: 3.8.1
 %End
 
   signals:

diff --git a/src/core/providers/memory/qgsmemoryprovider.cpp b/src/core/providers/memory/qgsmemoryprovider.cpp
@@ -359,6 +359,17 @@ QgsCoordinateReferenceSystem QgsMemoryProvider::crs() const
   return mCrs; // return default CRS
 }
 
+void QgsMemoryProvider::handlePostCloneOperations( QgsVectorDataProvider *source )
+{
+  if ( QgsMemoryProvider *other = qobject_cast< QgsMemoryProvider * >( source ) )
+  {
+    // these properties aren't copied when cloning a memory provider by uri, so we need to do it manually
+    mFeatures = other->mFeatures;
+    mNextFeatureId = other->mNextFeatureId;
+    mExtent = other->mExtent;
+  }
+}
+
 
 bool QgsMemoryProvider::addFeatures( QgsFeatureList &flist, Flags )
 {

diff --git a/src/core/providers/memory/qgsmemoryprovider.h b/src/core/providers/memory/qgsmemoryprovider.h
@@ -78,6 +78,7 @@ class QgsMemoryProvider : public QgsVectorDataProvider
     void updateExtents() override;
     bool isValid() const override;
     QgsCoordinateReferenceSystem crs() const override;
+    void handlePostCloneOperations( QgsVectorDataProvider *source ) override;
 
   private:
     // Coordinate reference system

diff --git a/src/core/qgsvectordataprovider.cpp b/src/core/qgsvectordataprovider.cpp
@@ -841,3 +841,8 @@ QList<QgsRelation> QgsVectorDataProvider::discoverRelations( const QgsVectorLaye
 {
   return QList<QgsRelation>();
 }
+
+void QgsVectorDataProvider::handlePostCloneOperations( QgsVectorDataProvider * )
+{
+
+}
diff --git a/src/core/qgsvectordataprovider.h b/src/core/qgsvectordataprovider.h
@@ -601,6 +601,14 @@ class CORE_EXPORT QgsVectorDataProvider : public QgsDataProvider, public QgsFeat
      */
     virtual bool hasMetadata() const { return true; }
 
+    /**
+     * Handles any post-clone operations required after this vector data provider was cloned
+     * from the \a source provider.
+     *
+     * \since QGIS 3.8.1
+     */
+    virtual void handlePostCloneOperations( QgsVectorDataProvider *source );
+
   signals:
 
     /**

diff --git a/src/core/qgsvectorlayer.cpp b/src/core/qgsvectorlayer.cpp
@@ -217,6 +217,10 @@ QgsVectorLayer *QgsVectorLayer::clone() const
     options.transformContext = mDataProvider->transformContext();
   }
   QgsVectorLayer *layer = new QgsVectorLayer( source(), name(), mProviderKey, options );
+  if ( mDataProvider && layer->dataProvider() )
+  {
+    layer->dataProvider()->handlePostCloneOperations( mDataProvider );
+  }
   QgsMapLayer::clone( layer );
 
   QList<QgsVectorLayerJoinInfo> joins = vectorJoins();

diff --git a/tests/src/python/provider_python.py b/tests/src/python/provider_python.py
@@ -422,3 +422,6 @@ def isValid(self):
 
     def crs(self):
         return self._crs
+
+    def handlePostCloneOperations(self, source):
+        self._features = source._features
diff --git a/tests/src/python/providertestbase.py b/tests/src/python/providertestbase.py
@@ -278,6 +278,17 @@ def testOpenIteratorAfterLayerRemoval(self):
             pks.append(f['pk'])
         self.assertEqual(set(pks), {1, 2, 3, 4, 5})
 
+    def testCloneLayer(self):
+        """
+        Test that cloning layer works and has all expected features
+        """
+        l = self.vl.clone()
+
+        pks = []
+        for f in l.getFeatures():
+            pks.append(f['pk'])
+        self.assertEqual(set(pks), {1, 2, 3, 4, 5})
+
     def testGetFeaturesPolyFilterRectTests(self):
         """ Test fetching features from a polygon layer with filter rect"""
         try:

diff --git a/tests/src/python/test_provider_memory.py b/tests/src/python/test_provider_memory.py
@@ -226,6 +226,31 @@ def testAddFeatures(self):
 
             assert compareWkt(str(geom.asWkt()), "Point (10 10)"), myMessage
 
+    def testClone(self):
+        """
+        Test that cloning a memory layer also clones features
+        """
+        vl = QgsVectorLayer(
+            'Point?crs=epsg:4326&field=f1:integer&field=f2:integer',
+            'test', 'memory')
+        self.assertTrue(vl.isValid())
+
+        f1 = QgsFeature()
+        f1.setAttributes([5, -200])
+        f2 = QgsFeature()
+        f2.setAttributes([3, 300])
+        f3 = QgsFeature()
+        f3.setAttributes([1, 100])
+        res, [f1, f2, f3] = vl.dataProvider().addFeatures([f1, f2, f3])
+        self.assertEqual(vl.featureCount(), 3)
+
+        vl2 = vl.clone()
+        self.assertEqual(vl2.featureCount(), 3)
+        features = [f for f in vl2.getFeatures()]
+        self.assertTrue([f for f in features if f['f1'] == 5])
+        self.assertTrue([f for f in features if f['f1'] == 3])
+        self.assertTrue([f for f in features if f['f1'] == 1])
+
     def testGetFields(self):
         layer = QgsVectorLayer("Point", "test", "memory")
         provider = layer.dataProvider()