net/url: URL.String() double encodes path

[LouisMT]

What version of Go are you using (go version)?

$ go version
go version go1.10.4 linux/amd64

Does this issue reproduce with the latest release?

Yes.

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/louis/.cache/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/louis/go"
GORACE=""
GOROOT="/usr/lib/go-1.10"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go-1.10/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build814848893=/tmp/go-build -gno-record-gcc-switches"

What did you do?

package main

import (
	"log"
	"net/url"
)

func main() {
	apiURL, _ := url.Parse("https://gitlab.com")
	apiURL.Path = "api/v4/projects/0/repository/files/some%2Ffile/raw"
	log.Println(apiURL.String())
}

https://play.golang.org/p/SFl-9urTdRL

What did you expect to see?

(%2F)

2009/11/10 23:00:00 https://gitlab.com/api/v4/projects/0/repository/files/some%2Ffile/raw

What did you see instead?

(%252F)

2009/11/10 23:00:00 https://gitlab.com/api/v4/projects/0/repository/files/some%252Ffile/raw

---

I have to build an URL that contains both slashes and encoded slashes, because I'm using the GitLab API:

GET /projects/:id/repository/files/:file_path/raw

Parameters:

• file_path (required) - Url encoded full path to new file. Ex. lib%2Fclass%2Erb
• ref (required) - The name of branch, tag or commit

But when I call URL.String(), the path is escaped again. I read that this is intended behavior:

To obtain the path, String uses u.EscapedPath().

However, there seems to be no way to convert the URL to a string without automatically escaping the path. I think this should be an option for the URL.String() method, or there should be an URL.RawString() method of some kind.

Related: #25208, #10887

[crvv]

This is not about the String() method. The problem is what the URL is.
Why not use https://play.golang.org/p/eQzYBMgUQtz ?
it returns the expected string.

[LouisMT]

Because I'm building the URL dynamically. In my example, I could've used url.Parse, but it was just to show the issue in a simple way. In my application, I'm building the URL by setting various properties of the URL object. That way it's not possible to do this.

[andybons]

@bradfitz

[bradfitz]

Sounds like you just need to use RawPath.