[BUG] URL slash encoded

Describe the bug

FastAPI is not routing URL containing slash encoded.

To Reproduce

1. Create a file with:

from fastapi import FastAPI
app = FastAPI()


@app.get("/units/{unit}")
def read_unit(unit: str):
    return {"unit": unit}

1. Open the browser and call the endpoint /units/kg%2Fs.
2. It returns Status 404 with JSON with {"detail":"Not Found"}.
3. But I expected it to return {"unit": "kg/s"}.
4. Working with /units/kg, returning {"unit": "kg"}.

Expected behavior

FastAPI working with URL encoded slash

Environment

• OS: Windows
• FastAPI Version : 0.45.0
• Python 3.7.3

Additional context

Starlette regexp seems fine though when testing it returns this route regexp:

'^/units/(?P<unit>[^/]+)$'

>>> import re
>>> pattern=re.compile('^/units/(?P<unit>[^/]+)$')
>>> pattern.match('/units/kg%2Fs')
<re.Match object; span=(0, 13), match='/units/kg%2Fs'>
>>> pattern.match('/units/kg%2Fs').groupdict()["unit"]
'kg%2Fs'

[jules-ch]

@Gatsby-Lee

If you want to keep this kind of behavior with slash in your routing path. You can use this workaround with a specific character to split your url, like - or #. We can do that with starlette with the routing convertors path (https://www.starlette.io/routing/).

Keeping my example, you can try the following:

from fastapi import FastAPI

app = FastAPI()


@app.get("/units/-/{unit:path}")
def read_unit(unit: str):
    return {"unit": unit}

You can now visit the URL http://127.0.0.1:8000/units/-/kg/s which will outputs :

{"unit":"kg/s"}

[Menotomy]

@jules-ch I came across this issue and tried your suggestion for something similar and it worked. My use case was returning the name of a specific interface in a network router. Network routers have names with slashes, like et-1/0/0 (Ethernet HundredGig in this case). This means the URL needs to look like et-1%2f0%2f0, as %2f is for a / character.

With the route

@app.get('/cfg/interfaces/interface/{int_name}')
def get_int(int_name: str):

the URL sent to FastAPI would be http://1.2.3.4:8000/cfg/interfaces/interface/et-1/0/0 which is an incorrect route resulting in a 404 Not Found.

I followed your suggestion with adding :path and the route worked.

@app.get('/cfg/interfaces/interface/{int_name:path}')
def get_int(int_name: str):

The function was able to parse XML using xpath, using that variable for the interface name.

Just confirming and providing an additional example of anyone that sees this.