Rewrite empty Fields on Feeds periodic Import I have set up a periodic feed importer in drupal which imports nodes and updates existing nodes.

Lets assume the imported xml consits of two fields: the title and a long text field. 

I import the nodes in the morning with the following content:

title   long text field
1       long text 1
2       long text 2
3       long text 3


So three nodes were correctly created with the two fields. But if I import later and the content of the xml has changed to the following:

title   long text field
1       long text 1
2       
3       long text 3


As you can see the long text field of the second node is empty, but feeds doesn't update the field. The value after reimport is still 'long text 2'. 

I haven't found an option or a module to achieve this. I have tried to manipulate the input data via 

hook_feeds_after_parse(FeedsSource $source, FeedsParserResult $result) {
  // replace empty results with ' ' (one space), so they gets replaced
  for ($i=0; $i &lt; sizeof($result-&gt;items); $i++) { 
    for ($o=0; $o &lt; sizeof($result-&gt;items[$i]); $o++) { 
      if (empty($result-&gt;items[$i]['xpathparser:'.$o])) {
        $result-&gt;items[$i]['xpathparser:'.$o] = ' ';
      }
    }
  }
}


But feeds only jumps into the function if it detects changes in the xml, but i think empty fields don't get considered.
Yes, this is a known problem of feeds. However, there is a patch for it and will be included in the next release as I know. You can already apply the patch now yourself:https: www.drupal.org/node/1107522
It is #161 in the link above.

I am using it for a while and tested it too, it works for your scenario above.
There is one problem with email and URL fields: Feeds still creates the field when the import is empty and this results in empty fields shown.