Implement HTTPException set_cookie() and del_cookie() methods

[asvetlov]

See aio-libs/aiohttp-session#396 for the context.

Implementation thoughts:

1. .cookies property is also needed
2. set_cookie() and del_cookie() should update headers immediately, HTTPException has no .prepare() method and should not have it.
3. Backport is not needed, in 3.x HTTPException is derived from Response and have all mentioned methods already.

[derlih]

@asvetlov

set_cookie() and del_cookie() should update headers immediately,

Is this requirement strict? Even if HTTPException will have no prepare()?

[asvetlov]

Do you mean that headers['Cookie'] is not updated before StreamResponse.prepare() call?

You are right, perhaps we should keep the consistency here.

[derlih]

I mean in the code:

aiohttp/aiohttp/web_protocol.py

Lines 447 to 463 in 488b375

	async def _handle_request(
	self,
	request: BaseRequest,
	start_time: float,
	) -> Tuple[StreamResponse, bool]:
	assert self._request_handler is not None
	try:
	try:
	self._current_request = request
	resp = await self._request_handler(request)
	finally:
	self._current_request = None
	except HTTPException as exc:
	resp = Response(
	status=exc.status, reason=exc.reason, text=exc.text, headers=exc.headers
	)
	reset = await self.finish_response(request, resp, start_time)

The data is copied from HTTPException to Response. Cookies can be copied as well. And prepare() will be called on that response instance.

[asvetlov]

Ok.

[derlih]

@asvetlov can this issue be closed?