Use "308 Permanent Redirect" for redirect slashes behavior.

Hi, I stumbled upon a quirk in starlette that is not properly documented. It seems like all of my HTTP request to a route without trailing slash are being redirected to route with trailing slashes. Say I am hitting http://hostname/mountpoint/api it will be redirected (302) to http://hostname/mountpoint/api/. This messed up your api calls; if you call POST to http://hostname/mountpoint/api it will be redirected to GET http://hostname/mountpoint/api/.

I dig on the source and see this redirect_slashes flag and setting it to False fix this. I feel this behavior (the auto redirection) should be documented.

[hjkelly]

I’m new to fastapi, and I think I’m running into this issue as well. If I forget a necessary slash, I’m redirected, which has no side effects for GET, but POST loses its data and is changed to a GET.

I’m new to this tool, but I’ve used Django for a decade, as well as django-rest-framework. Django’s APPEND_SLASH=True breaks non-GET requests. django-rest-framework provides routers for their viewsets, but you have to override the __init__ method to make trailing slashes optional. Even then, @action subresources must have trailing slashes. In my opinion, that functionality has always seemed broken.

Instead of modifying the docs to clarify this, what if the routes were forgiving of slash confusion? Instead of 404ing or even redirecting, compile_path could just ensure there’s a /? instead of / or no slash at all. I suggest this because I’ve made incorrectly-slashed requests hundreds of times over the years, and doing this with POST requests can result in confusion or even lost data. In contrast, it seems unlikely that someone would miss the ability to specify routes only with trailing slashes, or _only when there is no trailing slash.

Let me know what you think or if I can help.

[tomchristie]

@tibudiyanto Absolutely agreed. No particular need for us to allow it to be configurable either - it’s clearly the wrong code as it stands.