[FEATURE] Add support for attribute renaming to QgsVectorDataProvider

Implemented in memory layer provider only, not yet supported
in edit buffer or configurable in GUI

Author: nyalldawson

python/core/qgsvectordataprovider.sip

@@ -54,7 +54,9 @@ class QgsVectorDataProvider : QgsDataProvider
       /** Supports joint updates for attributes and geometry
        * Providers supporting this should still define ChangeGeometries | ChangeAttributeValues
        */
-      ChangeFeatures
+      ChangeFeatures,
+      /** Supports renaming attributes (fields). Added in QGIS 2.16 */
+      RenameAttributes,
     };
 
     /** Bitmask of all provider's editing capabilities */
@@ -205,6 +207,14 @@ class QgsVectorDataProvider : QgsDataProvider
      */
     virtual bool deleteAttributes( const QSet<int> &attributes );
 
+    /**
+     * Renames existing attributes.
+     * @param renamedAttributes map of attribute index to new attribute name
+     * @return true in case of success and false in case of failure
+     * @note added in QGIS 2.16
+     */
+    virtual bool renameAttributes( const QgsFieldNameMap& renamedAttributes );
+
     /**
      * Changes attribute values of existing features.
      * @param attr_map a map containing changed attributes

src/core/qgsvectordataprovider.cpp

@@ -81,6 +81,12 @@ bool QgsVectorDataProvider::deleteAttributes( const QgsAttributeIds &attributes
   return false;
 }
 
+bool QgsVectorDataProvider::renameAttributes( const QgsFieldNameMap& renamedAttributes )
+{
+  Q_UNUSED( renamedAttributes );
+  return false;
+}
+
 bool QgsVectorDataProvider::changeAttributeValues( const QgsChangedAttributesMap &attr_map )
 {
   Q_UNUSED( attr_map );

src/core/qgsvectordataprovider.h

@@ -102,12 +102,15 @@ class CORE_EXPORT QgsVectorDataProvider : public QgsDataProvider
       /** Supports joint updates for attributes and geometry
        * Providers supporting this should still define ChangeGeometries | ChangeAttributeValues
        */
-      ChangeFeatures =                              1 << 18
+      ChangeFeatures =                              1 << 18,
+      /** Supports renaming attributes (fields). Added in QGIS 2.16 */
+      RenameAttributes =                            1 << 19,
     };
 
     /** Bitmask of all provider's editing capabilities */
     const static int EditingCapabilities = AddFeatures | DeleteFeatures |
-                                           ChangeAttributeValues | ChangeGeometries | AddAttributes | DeleteAttributes;
+                                           ChangeAttributeValues | ChangeGeometries | AddAttributes | DeleteAttributes |
+                                           RenameAttributes;
 
     /**
      * Constructor of the vector provider
@@ -254,6 +257,14 @@ class CORE_EXPORT QgsVectorDataProvider : public QgsDataProvider
      */
     virtual bool deleteAttributes( const QgsAttributeIds &attributes );
 
+    /**
+     * Renames existing attributes.
+     * @param renamedAttributes map of attribute index to new attribute name
+     * @return true in case of success and false in case of failure
+     * @note added in QGIS 2.16
+     */
+    virtual bool renameAttributes( const QgsFieldNameMap& renamedAttributes );
+
     /**
      * Changes attribute values of existing features.
      * @param attr_map a map containing changed attributes

src/providers/memory/qgsmemoryprovider.cpp

@@ -375,7 +375,6 @@ bool QgsMemoryProvider::addAttributes( const QList<QgsField> &attributes )
 {
   for ( QList<QgsField>::const_iterator it = attributes.begin(); it != attributes.end(); ++it )
   {
-    // Why are attributes restricted to int,double and string only?
     switch ( it->type() )
     {
       case QVariant::Int:
@@ -404,6 +403,30 @@ bool QgsMemoryProvider::addAttributes( const QList<QgsField> &attributes )
   return true;
 }
 
+bool QgsMemoryProvider::renameAttributes( const QgsFieldNameMap& renamedAttributes )
+{
+  QgsFieldNameMap::const_iterator renameIt = renamedAttributes.constBegin();
+  bool result = true;
+  for ( ; renameIt != renamedAttributes.constEnd(); ++renameIt )
+  {
+    int fieldIndex = renameIt.key();
+    if ( fieldIndex < 0 || fieldIndex >= mFields.count() )
+    {
+      result = false;
+      continue;
+    }
+    if ( mFields.indexFromName( renameIt.value() ) >= 0 )
+    {
+      //field name already in use
+      result = false;
+      continue;
+    }
+
+    mFields[ fieldIndex ].setName( renameIt.value() );
+  }
+  return result;
+}
+
 bool QgsMemoryProvider::deleteAttributes( const QgsAttributeIds& attributes )
 {
   QList<int> attrIdx = attributes.toList();
@@ -506,7 +529,7 @@ bool QgsMemoryProvider::createSpatialIndex()
 int QgsMemoryProvider::capabilities() const
 {
   return AddFeatures | DeleteFeatures | ChangeGeometries |
-         ChangeAttributeValues | AddAttributes | DeleteAttributes | CreateSpatialIndex |
+         ChangeAttributeValues | AddAttributes | DeleteAttributes | RenameAttributes | CreateSpatialIndex |
          SelectAtId | SelectGeometryAtId | CircularGeometries;
 }
 

src/providers/memory/qgsmemoryprovider.h

@@ -89,6 +89,8 @@ class QgsMemoryProvider : public QgsVectorDataProvider
      */
     virtual bool addAttributes( const QList<QgsField> &attributes ) override;
 
+    virtual bool renameAttributes( const QgsFieldNameMap& renamedAttributes ) override;
+
     /**
      * Deletes existing attributes
      * @param attributes a set containing names of attributes
@@ -132,7 +134,6 @@ class QgsMemoryProvider : public QgsVectorDataProvider
      */
     virtual int capabilities() const override;
 
-
     /* Implementation of functions from QgsDataProvider */
 
     /**

tests/src/python/test_provider_memory.py

@@ -262,6 +262,44 @@ def testSaveFields(self):
         for f in myFields:
             assert f == importedFields.field(f.name())
 
+    def testRenameAttributes(self):
+        layer = QgsVectorLayer("Point", "test", "memory")
+        provider = layer.dataProvider()
+
+        res = provider.addAttributes([QgsField("name", QVariant.String, ),
+                                      QgsField("age", QVariant.Int),
+                                      QgsField("size", QVariant.Double)])
+        layer.updateFields()
+        assert res, "Failed to add attributes"
+        ft = QgsFeature()
+        ft.setGeometry(QgsGeometry.fromPoint(QgsPoint(10, 10)))
+        ft.setAttributes(["Johny",
+                          20,
+                          0.3])
+        res, t = provider.addFeatures([ft])
+
+        # bad rename
+        self.assertFalse(provider.renameAttributes({-1: 'not_a_field'}))
+        self.assertFalse(provider.renameAttributes({100: 'not_a_field'}))
+        # already exists
+        self.assertFalse(provider.renameAttributes({1: 'name'}))
+
+        # rename one field
+        self.assertTrue(provider.renameAttributes({1: 'this_is_the_new_age'}))
+        self.assertEqual(provider.fields().at(1).name(), 'this_is_the_new_age')
+        layer.updateFields()
+        fet = next(layer.getFeatures())
+        self.assertEqual(fet.fields()[1].name(), 'this_is_the_new_age')
+
+        # rename two fields
+        self.assertTrue(provider.renameAttributes({1: 'mapinfo_is_the_stone_age', 2: 'super_size'}))
+        self.assertEqual(provider.fields().at(1).name(), 'mapinfo_is_the_stone_age')
+        self.assertEqual(provider.fields().at(2).name(), 'super_size')
+        layer.updateFields()
+        fet = next(layer.getFeatures())
+        self.assertEqual(fet.fields()[1].name(), 'mapinfo_is_the_stone_age')
+        self.assertEqual(fet.fields()[2].name(), 'super_size')
+
 
 class TestPyQgsMemoryProviderIndexed(unittest.TestCase, ProviderTestCase):