proposal: net/http: support slash (/) in path variable

[WestleyK]

Proposal Details

It would be really nice if the path variables can support / in the variable, example GET /api/{resource_name}/components/info only matches /api/resource_name/components/info, and not /api/resource/name/components/info. You can url encode the slash in resource name like resource%2fname, and that does work, but not what I'm looking for.

I understand we may not want to default handle / in the path variable, but maybe an option to enable it, like {resource_name/2} for 2 slashes and {resource_name/*} for any amount.

You also cant do GET /api/{resource_name...}/components/info, which would also solve the issue I'm proposing.

Example go code

package main

import (
	"log"
	"net/http"
)

func main() {
	mux := http.NewServeMux()

	mux.Handle("GET /api/{resource_name}/components/info", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte(r.PathValue("resource_name")))
	}))

	s := http.Server{Handler: mux, Addr: ":8000"}

	log.Fatalln(s.ListenAndServe())
}

$ curl localhost:8000/api/resource_name/components/info
resource_name

$ curl localhost:8000/api/resource/name/components/info
404 page not found

$ curl localhost:8000/api/resource%2fname/components/info
resource/name

[ianlancetaylor]

CC @jba

[jba]

I think that if we allowed "..." wildcards in the middle, checking two patterns for conflict would become superlinear. I'm not positive, but that's my feeling. If there were just one wildcard, as in your example, it would be easy, but with multiple ones it seems hard.

If you want to match a fixed number of segments, you can write one pattern for each.

I think this is a likely decline.

[WestleyK]

My specific use case has a lot of apis for resource_name, and resource_name allows for any number of slashes in it, I would need to make many (easily 20+) patterns, which is not maintainable. Third-party server mux (I think gorilla, chi, etc...) you can do this. But it would be really nice if you can do this with without a third-party library.

[jba]

resource_name allows for any number of slashes in it

Typically, something like that goes at the end of the path. For example, Google Cloud Platform URLs work like that. In some cases I believe they add a :something to the end if they need one more thing; the last segment is then last_part_of_name:word, which in Go would be parsed in code.

[WestleyK]

I agree that there are better ways to implement this, I'm familiar with those api standards, unfortunately some existing apis I cannot change.

I appreciate your time and understanding in reviewing this proposal.