[web2py] opening a uploaded file in db from controller

[Umpei Kurokawa]

So I have a table in the database like this.

db.define_table('seed_file',
   Field('title','string'),
   Field('file','upload'), 
   format='%(title)s')

And I want to open the uploaded files from this table from the controller 
for further manipulation. Using open() function on file, I get an error 
saying that it cannot find the file. 
How is this done exactly?