File_column not working properly

Hello,

In my application, I have to show a form to allow updating a table row
and also upload a logo file related to that row. The db record only
needs to save the filename and file could be saved anywhere else on the
server. In my controller I have to validate other fields and if they are
valid only then upload the file and update the db also.

I am trying to use file_column for upload and it does save the file in
tmp folder. But the problem is that it is not saved in the folder as
defined by the file_column plugin. It is saved only when I come back to
the same screen and submit the form again, only then it is deleted from
tmp and saved at the proper location.

Now, what am I doing wrong here? Why does the form needs to be submitted
again? Somewhere on this forum I read that I need to use
update_attributes to update the db. But even that causes the same
result.

Any help will be appreciated very much.

Thanks.