[gen] Added px.override allowing to modify PX code; bugfixes; added migration code for converting File instances to FileInfo instances.

fields/file.py

@@ -181,7 +181,7 @@ class File(Field):
 
     pxView = pxCell = Px('''
      <x var="downloadUrl='%s/download?name=%s' % (zobj.absolute_url(), name);
-             shownSize=value.getShownSize()">
+             shownSize=value and value.getShownSize() or 0">
       <x if="value and not field.isImage">
        <a href=":downloadUrl">:value.uploadName</a>&nbsp;&nbsp;-
        <i class="discreet">:shownSize</i>
@@ -319,7 +319,11 @@ class File(Field):
             dbFolder, folder = zobj.getFsFolder(create=True)
             # Remove the previous file if it existed.
             info = getattr(obj.aq_base, self.name, None)
-            if info: info.removeFile(dbFolder)
+            if info:
+                # The previous file can be a legacy File object in an old
+                # database we are migrating.
+                if isinstance(info, FileInfo): info.removeFile(dbFolder)
+                else: delattr(obj, self.name)
             # Store the new file. As a preamble, create a FileInfo instance.
             info = FileInfo(folder)
             cfg = zobj.getProductConfig()

fields/group.py

@@ -306,7 +306,7 @@ class UiGroup:
       <!-- Group content -->
       <div var="display=expanded and 'display:block' or 'display:none'"
            id=":field.labelId" style=":'padding-left: 10px; %s' % display">
-       <x for="searches in field.widgets">
+       <x for="searches in field.elements">
         <x for="elem in searches">
          <!-- An inner group within this group -->
          <x if="elem.type == 'group'"