Add API to easily send JSON as request body

[socketpair]

i.e. some shortcut for

data = {'answer': 42}
client_session.post(
    'http://example.com',
    data=json.dumps(answer),
    headers={'content-type': 'application/json'}
)

[socketpair]

Tornado automatically makes json.dumps + set content-type when it see that isinstance(data, dict). This covers many usecases. But even with this, we needed to patch tornado. We send lists as json. So, as I think, most intuitive API will be:

• post(json=..). -- calls json.dumps() and sets content-type application/json (if content-type was not set using headers=...
• post(text=..). -- calls .encode('utf-8') and sets content-type text/plain; charset=utf-8 (if content-type was not set using headers=...

This will match how the web.Response() works. But unfortunatelly only for data=... and text=.... Also, it will be nice to add json=... to web.Response, and say that web.json_response is obsolete.

[fafhrd91]

we can add payload for dict and list, something like https://github.com/aio-libs/aiohttp/blob/master/aiohttp/payload.py#L199

I'd add "json=" and "text=" but we should be very careful, request() method has so many parameters already.

[AraHaan]

discord.py can request json like so (They basically made a class that creates their own request function that has an param named json

import aiohttp
import asyncio
import json

class HTTPClient:
    def __init__(self, loop, *args, *kwargs):
        self.loop = loop
        self.session = aiohttp.ClientSession(loop=self.loop, *args, **kwargs)

    @asyncio.coroutine
    def request(self, url, method, **kwargs):
        if 'json' in kwargs:
            headers['Content-Type'] = 'application/json'
            kwargs['headers'] = headers
            kwargs['data'] = json.dumps(kwargs.pop('json'), separators=(',', ':'), ensure_ascii=True)
        r = yield from self.session.request(method, url, **kwargs)
        yield from r.release()

As you can see json can be passed just fine into data=.

[fafhrd91]

added json parameter, but I am not sure about text

[fafhrd91]

regarding json for web.Response(), @asvetlov has some reasons not to add json.
@asvetlov could you clarify?

[socketpair]

Great! I have now more reasons to throw out Tornado from our projects!

[jettify]

previous discussion about json inweb.Response() #592

[fafhrd91]

added separate ticket for web.Response

[lock]

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