sitetree/admin.py
def save_model(self, request, obj, form, change):
        """Saves TreeItem model under certain Tree.
        Handles item's parent assignment exception.

        """
        if change:
            # No, you're not allowed to make item parent of itself
            if obj.parent is not None and obj.parent.id == obj.id:
                obj.parent = self.previous_parent
                messages.warning(
                    request, _("Item's parent left unchanged. Item couldn't be parent to itself."), '', True)
        obj.tree = self.tree
        obj.save()
def save_model(self, request, obj, form, change):
        """Saves TreeItem model under certain Tree.
        Handles item's parent assignment exception.

        """
        if change:
            # No, you're not allowed to make item parent of itself
            if obj.parent is not None and obj.parent.id == obj.id:
                obj.parent = self.previous_parent
                messages.warning(
                    request, _("Item's parent left unchanged. Item couldn't be parent to itself."), '', True)
        obj.tree = self.tree
        obj.save()
Saves TreeItem model under certain Tree.
        Handles item's parent assignment exception.