BEFORE UPDATE trigger doesn't change column value

[Clemens Eisserer <linuxhippy@xxxxxxxxx>]

Hi,

Sorry for this newbie-question, I am trying for quite some time now to get the following trigger-function to work properly:

CREATE OR REPLACE FUNCTION update_synced_column()
  RETURNS trigger AS
$BODY$
BEGIN
   IF NEW.synced IS NULL THEN
    NEW.synced :=  false;
   END IF;
   RETURN NEW;
END;
$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100;

The idea is basically to always update the "synced" column to false, unless a value has been provided manually in the UPDATE-clause.
Synced is defined as BOOLEAN DEFAULT FALSE;
I execute this function in a BEFORE UPDATE trigger FOR EACH ROW, however it doesn't seem to have any effect.

Any ideas what could be wrong here?

Thanks, Clemens