handle custom content types

[wuan]

What do these changes do?

When using a custom content type like application/vnd.aiohttp-test+json the client now ignores content type parameters (e. g. an encoding setting) when checking for matching types.

Are there changes in behavior for the user?

Nothing expected here. Clients which include the parameters in content_type (as a workaround) should still work.

Related issue number

#2206 is somehow related

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
• If you provide code modification, please add yourself to CONTRIBUTORS.txt
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[codecov-io]

Codecov Report

Merging #2594 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2594      +/-   ##
==========================================
+ Coverage   97.87%   97.87%   +<.01%     
==========================================
  Files          38       38              
  Lines        7304     7307       +3     
  Branches     1263     1263              
==========================================
+ Hits         7149     7152       +3     
  Misses         51       51              
  Partials      104      104

Impacted Files	Coverage Δ
aiohttp/helpers.py	97.82% <100%> (+0.01%)	⬆️
aiohttp/client_reqrep.py	97.23% <100%> (ø)	⬆️

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[asvetlov]

Sorry, I don't follow.
What problem do you want to solve?
What is Content-Type header for your server?

[wuan]

We are reading data via HTTP and get a response which has a Content-Type header in the form application/vnd.foo+json; encoding=utf-8.

To read JSON data from the response, the full content type has to be specified:

    data = response.json(content_type='application/vnd.foo+json; encoding=utf-8')

As json() already handles the encoding option according to the servers Content-Type header internally, it feels wrong to specify (and even fix) the encoding through the content type string. If the server leaves out that information some day it will even break the client.

This PR will allow us to use

    data = response.json(content_type='application/vnd.foo+json')

and still get a correct response with any of these Content-Type headers: application/vnd.foo+json; encoding=utf-8, application/vnd.foo+json; encoding=cp1251, application/vnd.foo+json

[asvetlov]

In requests .json() implementation is pretty simple: it doesn't accept custom content type and encoding.

I have a strong temptation to drop these params from aiohttp client too.

[asvetlov]

Supporting all non-standard combinations for custom json protocol makes a mess.

[wuan]

I would be fine with dropping the content type verification.

[asvetlov]

Let's close the PR as wontfix. 3bbe4d7 stresses a way for content type disabling

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a [new issue] for related bugs.
If you feel like there's important points made in this discussion, please include those exceprts into that [new issue].
[new issue]: https://github.com/aio-libs/aiohttp/issues/new