TypeError in URL.with_query

[dyus]

Hello, I have a problem with generating query_params. I try to make query

session = aiohttp.ClientSession()
session.request('get', 'some_url', {'p1': 1, 'p1': 2, 'p2': 3})

and got TypeError

  File "/lib/python3.5/site-packages/aiohttp/client.py", line 553, in __await__
    resp = yield from self._coro
  File "/lib/python3.5/site-packages/aiohttp/client.py", line 198, in _request
    proxy=proxy, proxy_auth=proxy_auth, timeout=timeout)
  File "lib/python3.5/site-packages/aiohttp/client_reqrep.py", line 79, in __init__
    url2 = url.with_query(params)
  File "/lib/python3.5/site-packages/yarl/__init__.py", line 675, in with_query
    raise TypeError("Invalid variable type")
TypeError: Invalid variable type

After some research I understand that Mapping with key: Sequence works with MultiDict. But this is not obvious. Maybe it should cast dict into MultiDict or return more descriptive warning or add logic for parsing Sequences in Mapping section

[asvetlov]

I prefer first option: casting dict into MultiDict.
Would you provide a patch?

[dyus]

Yes, I'll send pr today or tomorrow

[asvetlov]

After some research I understand that Mapping with key: Sequence works with MultiDict.

@dyus please elaborate.

>>> MultiDict(a=[1, 2, 3])
<MultiDict('a': [1, 2, 3])>

Result is a dict with single key and list as value.
It's not the same as three items with the same key:

>>> MultiDict([('a', 1), ('a', 2), ('a', 3)])
<MultiDict('a': 1, 'a': 2, 'a': 3)>

[dyus]

You mean dict_to_multidict should convert {'a': [1, 2, 3} into <MultiDict('a': [1, 2, 3])>'? This result is not a valid structure for URL.with_query` method.

n [5]: u = yarl.URL('http://123/')
In [6]: u.with_query(multidict.MultiDict({'a': [1,2,3]}))
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-6-6675a96330d2> in <module>()
----> 1 u.with_query(multidict.MultiDict({'a': [1,2,3]}))

/Users/a.zdanchuk/Envs/mobile_api/lib/python3.5/site-packages/yarl/__init__.py in with_query(self, *args, **kwargs)
    673                 #     v = '&'.join([str(i) for i in v])
    674                 else:
--> 675                     raise TypeError("Invalid variable type")
    676                 lst.append(quoter(k)+'='+quoter(v))
    677             query = '&'.join(lst)

TypeError: Invalid variable type

[asvetlov]

I don't want to support list values but added more verbose error messages: 4b9a94a