feat: annotate HttpRequest as readable, HttpResponse as writable

[alexei]

HttpRequests are readable, while HttpResponses are writable. It's insufficient that they have read and write methods respectively, as one would have to use a Protocol. However Reader and Writer are already available in the io package and are better suited.

[sobolevn]

you don't have to inherit from a protocol to make use of it. HttpRequest already should be compatible with Readable and HttpResponse should be compatible with Writable.

If you want, you can submit a test case for that.

[alexei]

It's my fault for not explaining this. I found this while writing to a response with a function that accepted a writable file-thing i.e. write_to_resp(content: bytes, output: Writer). I tried both IO and Writer on it and ty complained -- "Expected Writer, found HttpResponse". For file-like objects the Internet says to use IO, but the somewhat official recommendation is to use a Protocol, and that worked. Under these circumstances it should be reasonable to expect everyone to use IO or better yet Writer as they exist in the standard library.

[sobolevn]

io.Reader or typing_extensions.Reader is just:

@runtime_checkable
class Reader(Protocol[T_co]):
    """Protocol for simple I/O reader instances.

    This protocol only supports blocking I/O.
    """

    __slots__ = ()

    @abc.abstractmethod
    def read(self, size: int = ..., /) -> T_co:
        """Read data from the input stream and return it.

        If *size* is specified, at most *size* items (bytes/characters) will be
        read.
        """

So, you don't need to modify HttpRequest to use it. Because it is already supported, HttpRequest.read exists here

django-stubs/django-stubs/http/request.pyi

Line 117 in ca4389e

def read(self, n: int | None = -1, /) -> bytes: ...

and matches the Reader protocol.

As I said before you can add a test case to typesafety/assert_type that they indeed match:

to_read: Reader = HttpRequest()

And the same for HttpResponse.