django file upload doesn't work: f.read() returns ''

Question

I'm trying to upload and parse json files using django. Everything works great up until the moment I need to parse the json. Then I get this error:

No JSON object could be decoded: line 1 column 0 (char 0)

Here's my code. (I'm following the instructions here, and overwriting the handle_uploaded_file method.)

def handle_uploaded_file(f, collection):
#  assert False, [f.name, f.size, f.read()[:50]]
  t = f.read()
  for j in serializers.deserialize("json", t):
    add_item_to_database(j)

The weird thing is that when I uncomment the "assert" line, I get this:

[u'myfile.json', 59478, '']

So it looks like my file is getting uploaded with the right size (I've verified this on the server), but the read command seems to be failing entirely.

Any ideas?

Answer 1

I've seen this before. Your file has length, but reading it doesn't. I'm wondering if it's been read previously... try this:

f.seek(0)
f.read()