[20.12LTS] Remove prefix from websocket handler name

[laggardkernel]

Formerly try to open for master branch GH-2020. Cause the Router is overhauled on master, open this pr for 20.12LTS.

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Remove the websocket prefix websocket_handler_ introduced in
761eef7. Makes url_for() unable to find the corresponding ws route for non-bp websocket view.

@app.websocket('/ws')
async def websocket(request, ws):
    return ""

The key for the above handler used in Router.route_names is websocket_handler_websocket, not websocket. Removing the websocket_handler_ prefix fixes this bug. Searching in the source code, this very prefix is not used in anywhere.

I guess the contributor of commit 761eef7 tried to mimic the registration behavior of static file handler, which prepend the handler name with prefix _static_, in order to store static file handler separately in Router.routes_static_files, not in Router.routes_names.

[codecov]

Codecov Report

Merging #2021 (a7521f6) into 20.12LTS (9763511) will decrease coverage by 0.017%.
The diff coverage is 85.714%.

@@              Coverage Diff               @@
##           20.12LTS     #2021       +/-   ##
==============================================
- Coverage    92.796%   92.778%   -0.017%     
==============================================
  Files            29        29               
  Lines          3262      3268        +6     
  Branches        571       573        +2     
==============================================
+ Hits           3027      3032        +5     
  Misses          159       159               
- Partials         76        77        +1     

Impacted Files	Coverage Δ
sanic/app.py	95.868% <85.714%> (-0.157%)	⬇️
sanic/server.py	81.614% <0.000%> (ø)

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[laggardkernel]

During reading the source code. I've found inconsistent behaviors among route storing of normal http handler and websocket, static file handlers.

Firstly, the ways used to indicate a websocket handler and static file handler are different.

_static_ is prepend into name param from Sanic.static(name="static"). It's the same name param passed to Router._add(..., name). The _static_ is used as a flag in Router._add() to indicate current handler being registered is a static file handler, not used in anywhere else.

websocket.is_websocket is set in Sanic.websocket(), and the flag is only used in Sanic.handle_request().

Secondly, the ways to pass blueprint names of http handler, websocket handler, static file handler, to be used in Router._add() are different.

Formerly, only handler.__blueprintname__ is used. The bp name is prepended with handler name as the route name (key used in Router.routes_name, Router.routes_static_files) in Router._add().

For blueprint websocket handler (Blueprint.websocket()), not the original handler but a handler wrapper is passed to Router._add(). (Check Sanic._websocket_handler() and static._static_request_handler()) Seems later contributors (938c49b) didn't copy the __blueprintname__ attr to the handler wrapper. They chose to pass bp_name + handler to Router._add() directly. Similar thing happens on static file handler Blueprint.static() registration.

[ahopkins]

The new branch I am working on does not use any special prefixes for static or websockets. Also, there is a change to how routes are named in general. But I'll leave rhat discussion for #2010.

[ahopkins]

Since we are merging this into the LTS, I am hesitant to cause breaking changes. While I agree there is the issue with url_for, potentialling the name with the prefix are in use in some applications. Therefore I am thinking that we probably need to add support for both with and without the handler here.

I think the solution of removing the prefix does not consider a broader set of use cases.

[ahopkins]

Needs to handle fetching routes with and without so that it is not a breaking change.

[sjsadowski]

@laggardkernel are you able to implement @ahoplins request?

[laggardkernel]

@sjsadowski Just pushed an update with backward support, in case anyone find the bug and uses url_for("websocket_handler_<view_name>") in his code.

[ahopkins]

Looks great @laggardkernel. Can you add a test case to test_url_building.py for both cases?

Something like this. Also, one for Blueprints.

def test_url_for_with_websocket_handlers(app):
    @app.websocket("/ws")
    async def my_handler(...):
        ...
    
    assert app.url_for("my_handler") = "..."
    assert app.url_for("websocket_handler_my_handler") = "..."

[laggardkernel]

@ahopkins Thanks for pointing out the correct place to add the test. I've updated and squashed the commits.

[ahopkins]

Approved and will merge when Travis is done 🐢

I'll get this pushed out to the LTS tonight.

[ahopkins]

Thanks again for this.

[ahopkins]

@laggardkernel Can you address the CI issues? Linting issues can be fixed by running:

make pretty

[laggardkernel]

@ahopkins Sorry, fixed and passed the CI.