Question

I feel like I’m missing something terribly obvious, but I can’t see it.

In ipython (Python 2.7), this works:

In [1]: json.loads('[]')
Out[1]: []

I’m trying to do the equivalent minimal example in a Django view, to convince myself I can read JSON before moving on to a real data structure:

def submit(request):
    json_string = request.GET['json']
    parsed = json.loads(json_string)

    return HttpResponse(parsed)

I call it from my browser by going to

http://localhost:8001/submit/?json='[]'

And I get ValueError: No JSON object could be decoded.

What am I doing wrong, and how do I debug it? Is this some kind of encoding problem? Or am I accessing the content of the GET incorrectly? Or something else?

I’ve tried dumping the variable json_string, both to a file and as an HttpResponse. Both times I get '[]', which sure looks fine…

Edit:

For the benefit of any other beginners wondering how to debug a POST, Django’s error page is returned in the exception. A quick and nasty hack that works is

import os
def debug_post(post_req):

    result = None
    try:
        result = submit_to_endpoint(post_req)
    except urllib2.URLError as e:
        out_fh = open('debug_post.tmp', 'w')
        out_fh.write(e.read())
        out_fh.close()
        os.system('firefox ' + 'debug.tmp')

    return result

Answer 1

You’ve included the single quotes in the JSON string. There’s no need for that, especially as single quotes are not valid in JSON. You should go to http://localhost:8001/submit/?json=[].