Allow setting TreeModel values to None

Change TreeModel.set_value to use an empty but initialized GValue when
None is used as the value argument. This allows clearing of cell data
which was not accessible due to auto-coercion.

https://bugzilla.gnome.org/show_bug.cgi?id=684094

1 files changed, 8 insertions, 3 deletions

diff --git a/gi/overrides/Gtk.py b/gi/overrides/Gtk.py
index 223d8f4a..281a6803 100644
--- a/gi/overrides/Gtk.py
+++ b/gi/overrides/Gtk.py
@@ -872,11 +872,16 @@ class TreeModel(Gtk.TreeModel):
             self.set_value(treeiter, column, value)
 
     def _convert_value(self, column, value):
-        if value is None:
-            return None
-
         # we may need to convert to a basic type
         type_ = self.get_column_type(column)
+
+        # Allow None to be used as an initialized but empty value.
+        # https://bugzilla.gnome.org/show_bug.cgi?id=684094
+        if value is None:
+            value_container = GObject.Value()
+            value_container.init(type_)
+            return value_container
+
         if type_ == GObject.TYPE_STRING:
             if isinstance(value, str):
                 value = str(value)