ERP5Form: Returned field default value for ListBox was not consistent with non-ListBox field.

So, Relation Fields in ListBox were ignored during validation as the input
value is compared with the current (default), thus the field could not be
cleared as the value from the actual object was not retrieved at all.

product/ERP5Form/Form.py

@@ -226,13 +226,14 @@ class OverrideValue(StaticValue):
 
 class DefaultValue(StaticValue):
   def __init__(self, field_id, value):
-    self.key = field_id[3:]
+    self.key = field_id.split('_', 1)[1]
     self.value = value
 
   def __call__(self, field, id, **kw):
+    REQUEST = get_request()
     try:
       form = field.aq_parent
-      ob = getattr(form, 'aq_parent', None)
+      ob = REQUEST.get('cell', getattr(form, 'aq_parent', None))
       value = self.value
       try:
         if value not in (None, ''):
@@ -308,7 +309,8 @@ def getFieldValue(self, field, id, **kw):
 
   field_id = field.id
 
-  if id == 'default' and field_id.startswith('my_'):
+  if id == 'default' and (field_id.startswith('my_') or
+                          field_id.startswith('listbox_')):
     if field.meta_type == 'ProxyField' and \
         field.getRecursiveTemplateField().meta_type == 'CheckBoxField' or \
         self.meta_type == 'CheckBoxField':

product/ERP5Form/ProxyField.py

@@ -683,7 +683,8 @@ class ProxyField(ZMIField):
     value = copyMethod(value)
     cacheable = isCacheable(value)
 
-    if id == 'default' and field_id.startswith('my_'):
+    if id == 'default' and (field_id.startswith('my_') or
+                            field_id.startswith('listbox_')):
       # XXX far from object-oriented programming
       if template_field.meta_type == 'CheckBoxField':
         return DefaultCheckBoxValue(field_id, value), cacheable