Support custom JSON encoder/decoder

[binhnq94]

When i try do

session = yield from get_session(self.request)
session['user'] = user

with user is a document of mongo, my program occur a error:

Error handling request
Traceback (most recent call last):
  File "/usr/local/lib/python3.4/dist-packages/aiohttp/server.py", line 266, in start
    yield from self.handle_request(message, payload)
  File "/usr/local/lib/python3.4/dist-packages/aiohttp/web.py", line 90, in handle_request
    resp = yield from handler(request)
  File "/usr/local/lib/python3.4/dist-packages/aiohttp_session/__init__.py", line 144, in middleware
    yield from storage.save_session(request, response, session)
  File "/usr/lib/python3.4/asyncio/coroutines.py", line 141, in coro
    res = func(*args, **kw)
  File "/usr/local/lib/python3.4/dist-packages/aiohttp_session/cookie_storage.py", line 52, in save_session
    self._get_session_data(session)
  File "/usr/lib/python3.4/json/__init__.py", line 230, in dumps
    return _default_encoder.encode(obj)
  File "/usr/lib/python3.4/json/encoder.py", line 192, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/usr/lib/python3.4/json/encoder.py", line 250, in iterencode
    return _iterencode(o, 0)
  File "/usr/lib/python3.4/json/encoder.py", line 173, in default
    raise TypeError(repr(o) + " is not JSON serializable")
TypeError: ObjectId('56d07ade0686372f8e45b3f1') is not JSON serializable

How do i replace 'json' encoder with 'bson.json_until' encoder?
https://github.com/aio-libs/aiohttp_session/blob/master/aiohttp_session/cookie_storage.py#L51

[asvetlov]

Unfortunately using custom JSON serializer is not possible in current aiohttp_session version.

Adding encoder and decoder params to SimpleCookieStorage, EncryptedCookieStorage and NaClCookieStorage makes sense.

We are already accept these params in RedisStorage.

I suggest moving self._encoder and self._decoder to AbstractStorage constructor.

The patch is very easy.
I'll accept it without any additional test but documentation update is required (we've missed it even for RedisStorage, shame on me).

Any volunteers?

[asvetlov]

As workaround I suggest converting ObjectId to string and back manually on every access to session data but really prefer to have encoder/decoder support for every storage class.

The change deserves a new aiohttp_session release.

[binhnq94]

I am happy and look forward to becoming one comtributor.
in addition, I would like to ask how to commit a contribute code? ( i have seen answer here: http://aiohttp.readthedocs.org/en/stable/contributing.html, and I hope to help you )

i think that "moving self._encoder and self._decoder to AbstractStorage constructor" is a good way.

[asvetlov]

@TechBK you should create a Pull Request

[binhnq94]

😃 ok

[binhnq94]

@asvetlov hey, my friend. check Pull Request.

[itsbjoern]

I just came across this relatively old issue. Unless I'm missing something, is there a reason why @TechBK's change was never merged? If there is a reason I suggest closing this issue otherwise I'd get a PR ready soon. (Especially since his fork looks like he basically completed it)

[asvetlov]

Sorry, but I cannot find any related PR.

[panagiks]

I think @BFriedrichs refers to #31 .

[asvetlov]

Looks like @TechBK gave up after first review tour.
His PR need more love for polishing before merge.

[itsbjoern]

Correct, I missed that for some reason. I haven’t really looked into how much changed since then but I can’t imagine these changes wouldn’t be still applicable.

[asvetlov]

I suggest creating a new PR from scratch and discussing it.

[muazhari]

Are there any updates on this issue?

[muazhari]

The workaround to this issue is by defining a custom JSONEncoder to json_serialize argument in ClientSession like below:

class BaseClient:

    async def get_client_session(self):
        return aiohttp.ClientSession(base_url=client_config.CLIENT_TRANSACTION_URL,
                                     json_serialize=lambda object: json.dumps(
                                         object,
                                         indent=4,
                                         sort_keys=True,
                                         default=str)
                                     )