router

Documentation

Overview

Package httprouter is a trie based high performance HTTP request router.

A trivial example is:

package main

import (
    "fmt"
    "github.com/julienschmidt/httprouter"
    "net/http"
    "log"
)

func Index(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
    fmt.Fprint(w, "Welcome!\n")
}

func Hello(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
    fmt.Fprintf(w, "hello, %s!\n", ps.ByName("name"))
}

func main() {
    router := httprouter.New()
    router.GET("/", Index)
    router.GET("/hello/:name", Hello)

    log.Fatal(http.ListenAndServe(":8080", router))
}

The router matches incoming requests by the request method and the path. If a handle is registered for this path and method, the router delegates the request to that function. For the methods GET, POST, PUT, PATCH, DELETE and OPTIONS shortcut functions exist to register handles, for all other methods router.Handle can be used.

The registered path, against which the router matches incoming requests, can contain two types of parameters:

Syntax    Type
:name     named parameter
*name     catch-all parameter

Named parameters are dynamic path segments. They match anything until the next '/' or the path end:

Path: /blog/:category/:post

Requests:
 /blog/go/request-routers            match: category="go", post="request-routers"
 /blog/go/request-routers/           no match, but the router would redirect
 /blog/go/                           no match
 /blog/go/request-routers/comments   no match

Catch-all parameters match anything until the path end, including the directory index (the '/' before the catch-all). Since they match anything until the end, catch-all parameters must always be the final path element.

Path: /files/*filepath

Requests:
 /files/                             match: filepath="/"
 /files/LICENSE                      match: filepath="/LICENSE"
 /files/templates/article.html       match: filepath="/templates/article.html"
 /files                              no match, but the router would redirect

The value of parameters is saved as a slice of the Param struct, consisting each of a key and a value. The slice is passed to the Handle func as a third parameter. There are two ways to retrieve the value of a parameter:

// by the name of the parameter
user := ps.ByName("user") // defined by :user or *user

// by the index of the parameter. This way you can also get the name (key)
thirdKey   := ps[2].Key   // the name of the 3rd parameter
thirdValue := ps[2].Value // the value of the 3rd parameter

Index

• Constants
• Variables
• func ResHandler[T any](c *contexti.Context[T], w http.ResponseWriter, result []reflect.Value)
• type Param
• type Params
  • func ParamsFromContext(ctx context.Context) Params
  • func (ps Params) ByName(name string) string
  • func (ps Params) MatchedRoutePath() string
• type Router
  • func New() *Router
  • func (r *Router) GroupUse(path string, middleware ...http.HandlerFunc)
  • func (r *Router) Handle(method, path string, middleware []http.HandlerFunc, handle reflect.Value)
  • func (r *Router) Handler(method, path string, handle ...http.HandlerFunc)
  • func (r *Router) ServeFiles(path string, root string)
  • func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request)
  • func (r *Router) Use(middleware ...http.HandlerFunc)

Constants

const MethodAny = "*"

Variables

var (
	HttpContextType = reflect.TypeOf((*httpctx.Context)(nil))
)

var MatchedRoutePathParam = "$matchedRoutePath"

MatchedRoutePathParam is the Param name under which the path of the matched route is stored, if Router.SaveMatchedRoutePath is set.

var ParamsKey = paramsKey{}

ParamsKey is the request context key under which URL params are stored.

Functions

func ResHandler

func ResHandler[T any](c *contexti.Context[T], w http.ResponseWriter, result []reflect.Value)

Types

type Param

type Param struct {
	Key   string
	Value string
}

Param is a single URL parameter, consisting of a key and a value.

type Params

type Params []Param

Params is a Param-slice, as returned by the router. The slice is ordered, the first URL parameter is also the first slice value. It is therefore safe to read values by the index.

func ParamsFromContext

func ParamsFromContext(ctx context.Context) Params

ParamsFromContext pulls the URL parameters from a request context, or returns nil if none are present.

func (Params) ByName

func (ps Params) ByName(name string) string

ByName returns the value of the first Param which key matches the given name. If no matching Param is found, an empty string is returned.

func (Params) MatchedRoutePath

func (ps Params) MatchedRoutePath() string

MatchedRoutePath retrieves the path of the matched route. Router.SaveMatchedRoutePath must have been enabled when the respective handler was added, otherwise this function always returns an empty string.

type Router

type Router struct {

	// If enabled, adds the matched route path onto the http.Request context
	// before invoking the handler.
	// The matched route path is only added to handlers of routes that were
	// registered when this option was enabled.
	SaveMatchedRoutePath bool

	// Enables automatic redirection if the current route can't be matched but a
	// handler for the path with (without) the trailing slash exists.
	// For example if /foo/ is requested but a route only exists for /foo, the
	// client is redirected to /foo with http status code 301 for GET requests
	// and 308 for all other request methods.
	RedirectTrailingSlash bool

	// If enabled, the router tries to fix the current request path, if no
	// handle is registered for it.
	// First superfluous path elements like ../ or // are removed.
	// Afterwards the router does a case-insensitive lookup of the cleaned path.
	// If a handle can be found for this route, the router makes a redirection
	// to the corrected path with status code 301 for GET requests and 308 for
	// all other request methods.
	// For example /FOO and /..//Foo could be redirected to /foo.
	// RedirectTrailingSlash is independent of this option.
	RedirectFixedPath bool

	// If enabled, the router checks if another method is allowed for the
	// current route, if the current request can not be routed.
	// If this is the case, the request is answered with 'Method Not Allowed'
	// and HTTP status code 405.
	// If no other Method is allowed, the request is delegated to the NotFound
	// handler.
	HandleMethodNotAllowed bool

	// If enabled, the router automatically replies to OPTIONS requests.
	// Customize OPTIONS handlers take priority over automatic replies.
	HandleOPTIONS bool

	// An optional http.Handler that is called on automatic OPTIONS requests.
	// The handler is only called if HandleOPTIONS is true and no OPTIONS
	// handler for the specific path was set.
	// The "Allowed" header is set before calling the handler.
	GlobalOPTIONS http.Handler

	// Configurable http.Handler which is called when no matching route is
	// found. If it is not set, http.NotFound is used.
	NotFound http.Handler

	// Configurable http.Handler which is called when a request
	// cannot be routed and HandleMethodNotAllowed is true.
	// If it is not set, http.Error with http.StatusMethodNotAllowed is used.
	// The "Allow" header with allowed request methods is set before the handler
	// is called.
	MethodNotAllowed http.Handler

	// Function to handle panics recovered from http handlers.
	// It should be used to generate a error page and return the http error code
	// 500 (Internal Server Error).
	// The handler can be used to keep your server from crashing because of
	// unrecovered panics.
	PanicHandler func(http.ResponseWriter, *http.Request, interface{})
	// contains filtered or unexported fields
}

Router is a http.Handler which can be used to dispatch requests to different handler functions via configurable routes

func New

func New() *Router

func (*Router) GroupUse

func (r *Router) GroupUse(path string, middleware ...http.HandlerFunc)

func (*Router) Handle

func (r *Router) Handle(method, path string, middleware []http.HandlerFunc, handle reflect.Value)

Handle registers a new request handle with the given path and method.

For GET, POST, PUT, PATCH and DELETE requests the respective shortcut functions can be used.

This function is intended for bulk loading and to allow the usage of less frequently used, non-standardized or custom methods (e.g. for internal communication with a proxy).

func (*Router) Handler

func (r *Router) Handler(method, path string, handle ...http.HandlerFunc)

func (*Router) ServeFiles

func (r *Router) ServeFiles(path string, root string)

ServeFiles serves files from the given file system root. The path must end with "/*filepath", files are then served from the local path /defined/root/dir/*filepath. For example if root is "/etc" and *filepath is "passwd", the local file "/etc/passwd" would be served. Internally a http.FileServer is used, therefore http.NotFound is used instead of the Router's NotFound handler. To use the operating system's file system implementation, use http.Dir:

router.ServeFiles("/src/*filepath", http.Dir("/var/www"))

func (*Router) ServeHTTP

func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request)

ServeHTTP makes the router implement the http.Handler interface.

func (*Router) Use

func (r *Router) Use(middleware ...http.HandlerFunc)