Python 3.6: get JSON from aiohttp request - json

Question

I have some application which uses aiohttp.
I sent POST request into approptiate endpoint, e.g.:
POST mysite.com/someendpoind/
with data similar to:
{"param1": "value1", "param2": "value2", ..., "paramn": None}
Then on backend side, I want to add some additional conditional into this request:
data = await request.json()
data["additional_conditional"] = True
But request.json() fails with an error:
[ERROR] Error handling request
Traceback (most recent call last):
File "/usr/local/lib/python3.5/dist-packages/aiohttp/web_protocol.py", line 422, in start
resp = yield from self._request_handler(request)
File "/usr/local/lib/python3.5/dist-packages/aiohttp/web.py", line 306, in _handle
resp = yield from handler(request)
File "/usr/local/lib/python3.5/dist-packages/aiohttp_session/__init__.py", line 129, in middleware
response = yield from handler(request)
File "/opt/bikeamp/auth/__init__.py", line 57, in wrapped
return (yield from f(request, user))
File "<my_module>.py", line 185, in <my_func>
data_json = await request.json()
File "/usr/local/lib/python3.5/dist-packages/aiohttp/web_request.py", line 469, in json
return loads(body)
File "/usr/lib/python3.5/json/__init__.py", line 319, in loads
return _default_decoder.decode(s)
File "/usr/lib/python3.5/json/decoder.py", line 339, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File "/usr/lib/python3.5/json/decoder.py", line 357, in raw_decode
raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
Then I decided to check somehow what is the content of my request:
await request.read()
b'field1=value1&field2=value2&field3=value3&field4=&field5=&field6='
So, I'm not sure, but the problem may be with empty parameters.
Also, I was trying to get this data via:
data = await request.post()
data["additional_condition"] = True
But this returns MultiDictProxy. Python can't pickle these objects.
Is there any known solutions?

Answer 1

I had the same issue, if post was something like {"email": "some#email.com"} check it with:
#router('/', methods=['POST', ])
async def post_request(request):
post = await request.post()
email = post.get('email') # because it's MultiDict
logging.warning(post) # see post details
logging.warning(email) # shows value "some#email.com"
json = await request.text() #
logging.warning(json) # shows json if it was ajax post request