Add getvalue to HttpResponse

[Claude Paroz]

The HttpResponse object can almost be used as another stream object. Unfortunately, it doesn't offer the getvalue() method to be able to read its content, hence requiring conditional code in some circonstances (see #15197). What about adding it (HttpResponse.getvalue() === HttpResponse.content)?

[Aymeric Augustin]

Good idea.

Do Python's docs provide a list of the methods that a "stream object" must support? While we're there, we should also check that HttpRequest objects support all the methods that make sense.

[Claude Paroz]

I think ​http://docs.python.org/library/io.html#io.IOBase lists basic API for streams.

[Unai Zalakain]

I would add the following attributes and methods:

• HttpResponseBase.closed: set to False in __init__, set to True in close()
• HttpResponseBase.writable(): returns False because write(content) raises an exception (should be changed to IOError BTW)
• HttpResponseBase.writelines(lines): raises IOError
• HttpResponseBase.tell(): change it to raise IOError
• HttpResponse.getvalue(): returns self.content
• HttpResponse.writelines(lines): writes each line with self.write(line)

[Michael Kelly]

I submitted a PR with the changes mentioned in comment:3 here: ​https://github.com/django/django/pull/2545 . If we think that all of the stuff from io.IOBase should be included, I can update my PR with the rest.

[Tim Graham]

There are some comments for improvement on the PR. Please uncheck "Patch needs improvement" when you update it, thanks.

[Michael Kelly]

Will do, just having trouble finding a good time to work on this lately. :D

[Michael Kelly]

Updated branch with changes in response to feedback.

[Tim Graham]

There are some problems with the tests on Python 3.

[Tim Graham <timograham@…>]

In ebc8e79cf3bdd42a99e91d6e679248d07097d3db:

Fixed #18523 -- Added stream-like API to HttpResponse.

Added getvalue() to HttpResponse to return the content of the response,
along with a few other methods to partially match io.IOBase.

Thanks Claude Paroz for the suggestion and Nick Sanford for review.