avoid overwriting of filename information in file fields when no file is uploaded

composer/schema/grid/field.py

@@ -148,8 +148,23 @@ class RecordsFieldInstance(GridFieldInstance):
         if not value:
             value = []
         result = []
+        oldValue = getattr(self.clientContext, self.name, [])
         for idx, row in enumerate(value):
             item = self.unmarshallRow(row, idx)
+            if item:
+                if len(oldValue) > idx:
+                    oldItem = oldValue[idx]
+                    for k, v in item.items():
+                        if v != '__no_change__':
+                            oldItem[k] = v
+                        #if oldItem.get(k) == '__no_change__':
+                        #    del oldItem[k]
+                    #if oldItem:
+                    result.append(oldItem)
+                else:
+                    for k, v in item.items():
+                        if v == '__no_change__':
+                            del item[k]
                     if item:
                         result.append(item)
         return result

composer/schema/instance.py

@@ -1,5 +1,5 @@
 #
-#  Copyright (c) 2007 Helmut Merz helmutm@cy55.de
+#  Copyright (c) 2013 Helmut Merz helmutm@cy55.de
 #
 #  This program is free software; you can redistribute it and/or modify
 #  it under the terms of the GNU General Public License as published by
@@ -18,8 +18,6 @@
 
 """
 Instance adapter classes for schemas.
-
-$Id$
 """
 
 from BTrees.OOBTree import OOBTree
@@ -110,7 +108,7 @@ class Editor(BaseInstance):
                 fieldHandlers[ftype](context, value, fi, formState)
             else:
                 oldValue = getattr(context, name, None)
-                if value != oldValue:
+                if value not in ('__no_change__', oldValue):
                     setattr(context, name, value)
                     fi.change = (oldValue, value)
                     formState.changed = True