python - Django's Querydict bizarre behavior: bunches POST dictionary into a single key

Question

I'm experiencing a really bizarre behavior when using the test client in django.

I'm using a POST to send data to my django app. I usually do this from an iPhone app and/or a test html form. On the server side, this is how I handle it:

def handle_query(request):
   print request
   q = con.QueryLog()
   q.ID = request.POST.get('ID', '')
   q.device = request.POST.get('device-model', '')
   ....

That print statement looks like what you would expect, i.e. each parameter in the post request is turned into a key in the dictionary:

POST: QueryDict: {u'app-version': [u'3.0'], u'server-version': [u'v3d0'],

However, I started writing some tests using Django's test client, and no matter what I try, the dictionary of POST parameters I send in the post request get bunched into a single key in the QueryDict. Allow me to illustrate with some code:

class SearchTest(TestCase): def setUp(self): pass

def test_search(self):
    request = HttpRequest()
    data = '{"amzn_locale": "com"}'
    # request._raw_post_data = data
    resp = self.client.post(
        '/is/', 
        data=data,
        content_type='application/x-www-form-urlencoded',
        # content_type='application/json',
        )

The same print statement on the server side shows the inexplicable grouping of the dictionary into a string:

POST: QueryDict: {u'{"amzn_locale":"com"}': [u'']}>,

If I set data to an actual dictionary, same thing

data = {"amzn_locale": "com"}

Setting the request._raw_post_data doesn't change anything. Nor does changing

content_type='application/json'

Any help would be much appreciated. From this stackoverflow question it seems like I'm not the first one to run into this iphone Json POST request to Django server creates QueryDict within QueryDict

Answer 1

The problem is that you're supplying a content_type. Since you did so, the client is expecting a urlencoded string like

"username=hi&password=there&this_is_the_login_form=1"

instead of a dictionary like

{'username': 'hi', 'password': 'there', 'this_is_the_login_form': 1}

If you remove the content_type kwarg you'll be fine.

Edit: As it turns out, the test client will look for a url-encoded string if you pass in any content_type other than MULTIPART_CONTENT - the content_type will only be used to figure out what charset to use to encode that url-encoded string. This is documented here. The relevant bit reads:

If you provide content_type (e.g., text/xml for an XML payload), the contents of data will be sent as-is in the POST request, using content_type in the HTTP Content-Type header.

If you don't provide a value for content_type, the values in data will be transmitted with a content type of multipart/form-data. In this case, the key-value pairs in data will be encoded as a multipart message and used to create the POST data payload.