Handle QgsDataItem class hierarchy in SIP bindings

Author: Hugo Mercier

python/core/qgsdataitem.sip

@@ -2,6 +2,23 @@ class QgsDataItem : QObject
 {
 %TypeHeaderCode
 #include <qgsdataitem.h>
+%End
+
+%ConvertToSubClassCode
+  if (qobject_cast<QgsLayerItem*>(sipCpp))
+    sipType = sipType_QgsLayerItem;
+  else if (qobject_cast<QgsErrorItem*>(sipCpp))
+    sipType = sipType_QgsErrorItem;
+  else if (qobject_cast<QgsDirectoryItem*>(sipCpp))
+    sipType = sipType_QgsDirectoryItem;
+  else if (qobject_cast<QgsFavouritesItem*>(sipCpp))
+    sipType = sipType_QgsFavouritesItem;
+  else if (qobject_cast<QgsZipItem*>(sipCpp))
+    sipType = sipType_QgsZipItem;
+  else if (qobject_cast<QgsDataCollectionItem*>(sipCpp))
+    sipType = sipType_QgsDataCollectionItem;
+  else
+    sipType = 0;
 %End
   public:
     enum Type