How to extract base url using golang

Given a url string, how to retrieve only the base url (i.e. protocol://host:port)

For example

> https://example.com/user/1000 => https://example.com

> https://localhost:8080/user/1000/profile => https://localhost:8080

I've tried parsing the url with url.Parse() but the net/url doesn't seem to have a method that returns the base url. I could try appending the individual parts of url to get the base url but I just wanted to check if there are any better alternatives to this.

I would parse it using url.Parse(), and zero the fields you don't want in the result, namely Path, RawQuery and Fragment. Then the result (base URL) can be acquired using URL.String().

For example:

u, err := url.Parse("https://user@pass:localhost:8080/user/1000/profile?p=n#abc")
if err != nil {
	panic(err)
}
fmt.Println(u)
u.Path = ""
u.RawQuery = ""
u.Fragment = ""
fmt.Println(u)
fmt.Println(u.String())

This will output (try it on the Go Playground):

https://user@pass:localhost:8080/user/1000/profile?p=n#abc
https://user@pass:localhost:8080
https://user@pass:localhost:8080

You can try

u, _ := url.Parse("https://example.com/user/1000")
val := fmt.Sprintf("%s://%s", u.Scheme, u.Host)

The following may be more useful in the general case.

rawURL := "https://user:pass@localhost:8080/user/1000/profile?p=n#abc"
u, _ := url.Parse(rawURL)
psw, pswSet := u.User.Password()
for _, d := range []struct {
	actual   any
	expected any
}{
	{u.Scheme, "https"},
	{u.User.Username(), "user"},
	{psw, "pass"},
	{pswSet, true},
	{u.Host, "localhost:8080"},
	{u.Path, "/user/1000/profile"},
	{u.Port(), "8080"},
	{u.RawPath, ""},
	{u.RawQuery, "p=n"},
	{u.Fragment, "abc"},
	{u.RawFragment, ""},
	{u.RequestURI(), "/user/1000/profile?p=n"},
	{u.String(), rawURL},
	{fmt.Sprintf("%s://%s", u.Scheme, u.Host), "https://localhost:8080"},
} {
	if d.actual != d.expected {
		t.Fatalf("%s\n%s\n", d.actual, d.expected)
	}
}

<kbd>go-playground</kbd>