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Published: Oct 8, 2015 License: BSD-3-Clause Imports: 6 Imported by: 0



Package url parses URLs and implements query escaping. See RFC 3986.




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func QueryEscape

func QueryEscape(s string) string

QueryEscape escapes the string so it can be safely placed inside a URL query.

func QueryUnescape

func QueryUnescape(s string) (string, error)

QueryUnescape does the inverse transformation of QueryEscape, converting %AB into the byte 0xAB and '+' into ' ' (space). It returns an error if any % is not followed by two hexadecimal digits.


type Error

type Error struct {
	Op  string
	URL string
	Err error

Error reports an error and the operation and URL that caused it.

func (*Error) Error

func (e *Error) Error() string

type EscapeError

type EscapeError string

func (EscapeError) Error

func (e EscapeError) Error() string

type URL

type URL struct {
	Scheme   string
	Opaque   string    // encoded opaque data
	User     *Userinfo // username and password information
	Host     string    // host or host:port
	Path     string
	RawPath  string // encoded path hint (Go 1.5 and later only; see EscapedPath method)
	RawQuery string // encoded query values, without '?'
	Fragment string // fragment for references, without '#'

A URL represents a parsed URL (technically, a URI reference). The general form represented is:


URLs that do not start with a slash after the scheme are interpreted as:


Note that the Path field is stored in decoded form: /%47%6f%2f becomes /Go/. A consequence is that it is impossible to tell which slashes in the Path were slashes in the raw URL and which were %2f. This distinction is rarely important, but when it is, code must not use Path directly.

Go 1.5 introduced the RawPath field to hold the encoded form of Path. The Parse function sets both Path and RawPath in the URL it returns, and URL's String method uses RawPath if it is a valid encoding of Path, by calling the EncodedPath method.

In earlier versions of Go, the more indirect workarounds were that an HTTP server could consult req.RequestURI and an HTTP client could construct a URL struct directly and set the Opaque field instead of Path. These still work as well.

package main

import (

func main() {
	u, err := url.Parse("http://bing.com/search?q=dotnet")
	if err != nil {
	u.Scheme = "https"
	u.Host = "google.com"
	q := u.Query()
	q.Set("q", "golang")
	u.RawQuery = q.Encode()

Example (Opaque)
package main

import (

func main() {
	// Sending a literal '%' in an HTTP request's Path
	req := &http.Request{
		Method: "GET",
		Host:   "example.com", // takes precedence over URL.Host
		URL: &url.URL{
			Host:   "ignored",
			Scheme: "https",
			Opaque: "/%2f/",
		Header: http.Header{
			"User-Agent": {"godoc-example/0.1"},
	out, err := httputil.DumpRequestOut(req, true)
	if err != nil {
	fmt.Println(strings.Replace(string(out), "\r", "", -1))

GET /%2f/ HTTP/1.1
Host: example.com
User-Agent: godoc-example/0.1
Accept-Encoding: gzip
Example (Roundtrip)
package main

import (

func main() {
	// Parse + String preserve the original encoding.
	u, err := url.Parse("https://example.com/foo%2fbar")
	if err != nil {


func Parse

func Parse(rawurl string) (url *URL, err error)

Parse parses rawurl into a URL structure. The rawurl may be relative or absolute.

func ParseRequestURI

func ParseRequestURI(rawurl string) (url *URL, err error)

ParseRequestURI parses rawurl into a URL structure. It assumes that rawurl was received in an HTTP request, so the rawurl is interpreted only as an absolute URI or an absolute path. The string rawurl is assumed not to have a #fragment suffix. (Web browsers strip #fragment before sending the URL to a web server.)

func (*URL) EscapedPath

func (u *URL) EscapedPath() string

EscapedPath returns the escaped form of u.Path. In general there are multiple possible escaped forms of any path. EscapedPath returns u.RawPath when it is a valid escaping of u.Path. Otherwise EscapedPath ignores u.RawPath and computes an escaped form on its own. The String and RequestURI methods use EscapedPath to construct their results. In general, code should call EscapedPath instead of reading u.RawPath directly.

func (*URL) IsAbs

func (u *URL) IsAbs() bool

IsAbs reports whether the URL is absolute.

func (*URL) Parse

func (u *URL) Parse(ref string) (*URL, error)

Parse parses a URL in the context of the receiver. The provided URL may be relative or absolute. Parse returns nil, err on parse failure, otherwise its return value is the same as ResolveReference.

func (*URL) Query

func (u *URL) Query() Values

Query parses RawQuery and returns the corresponding values.

func (*URL) RequestURI

func (u *URL) RequestURI() string

RequestURI returns the encoded path?query or opaque?query string that would be used in an HTTP request for u.

func (*URL) ResolveReference

func (u *URL) ResolveReference(ref *URL) *URL

ResolveReference resolves a URI reference to an absolute URI from an absolute base URI, per RFC 3986 Section 5.2. The URI reference may be relative or absolute. ResolveReference always returns a new URL instance, even if the returned URL is identical to either the base or reference. If ref is an absolute URL, then ResolveReference ignores base and returns a copy of ref.

package main

import (

func main() {
	u, err := url.Parse("../../..//search?q=dotnet")
	if err != nil {
	base, err := url.Parse("http://example.com/directory/")
	if err != nil {


func (*URL) String

func (u *URL) String() string

String reassembles the URL into a valid URL string. The general form of the result is one of:


If u.Opaque is non-empty, String uses the first form; otherwise it uses the second form. To obtain the path, String uses u.EncodedPath().

In the second form, the following rules apply:

- if u.Scheme is empty, scheme: is omitted.
- if u.User is nil, userinfo@ is omitted.
- if u.Host is empty, host/ is omitted.
- if u.Scheme and u.Host are empty and u.User is nil,
   the entire scheme://userinfo@host/ is omitted.
- if u.Host is non-empty and u.Path begins with a /,
   the form host/path does not add its own /.
- if u.RawQuery is empty, ?query is omitted.
- if u.Fragment is empty, #fragment is omitted.

type Userinfo

type Userinfo struct {
	// contains filtered or unexported fields

The Userinfo type is an immutable encapsulation of username and password details for a URL. An existing Userinfo value is guaranteed to have a username set (potentially empty, as allowed by RFC 2396), and optionally a password.

func User

func User(username string) *Userinfo

User returns a Userinfo containing the provided username and no password set.

func UserPassword

func UserPassword(username, password string) *Userinfo

UserPassword returns a Userinfo containing the provided username and password. This functionality should only be used with legacy web sites. RFC 2396 warns that interpreting Userinfo this way “is NOT RECOMMENDED, because the passing of authentication information in clear text (such as URI) has proven to be a security risk in almost every case where it has been used.”

func (*Userinfo) Password

func (u *Userinfo) Password() (string, bool)

Password returns the password in case it is set, and whether it is set.

func (*Userinfo) String

func (u *Userinfo) String() string

String returns the encoded userinfo information in the standard form of "username[:password]".

func (*Userinfo) Username

func (u *Userinfo) Username() string

Username returns the username.

type Values

type Values map[string][]string

Values maps a string key to a list of values. It is typically used for query parameters and form values. Unlike in the http.Header map, the keys in a Values map are case-sensitive.

package main

import (

func main() {
	v := url.Values{}
	v.Set("name", "Ava")
	v.Add("friend", "Jess")
	v.Add("friend", "Sarah")
	v.Add("friend", "Zoe")
	// v.Encode() == "name=Ava&friend=Jess&friend=Sarah&friend=Zoe"

[Jess Sarah Zoe]

func ParseQuery

func ParseQuery(query string) (m Values, err error)

ParseQuery parses the URL-encoded query string and returns a map listing the values specified for each key. ParseQuery always returns a non-nil map containing all the valid query parameters found; err describes the first decoding error encountered, if any.

func (Values) Add

func (v Values) Add(key, value string)

Add adds the value to key. It appends to any existing values associated with key.

func (Values) Del

func (v Values) Del(key string)

Del deletes the values associated with key.

func (Values) Encode

func (v Values) Encode() string

Encode encodes the values into “URL encoded” form ("bar=baz&foo=quux") sorted by key.

func (Values) Get

func (v Values) Get(key string) string

Get gets the first value associated with the given key. If there are no values associated with the key, Get returns the empty string. To access multiple values, use the map directly.

func (Values) Set

func (v Values) Set(key, value string)

Set sets the key to value. It replaces any existing values.

Source Files

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