middleware

README

middleware

Alice – Painless Middleware Chaining for Go

See: http://justinas.org/alice-painless-middleware-chaining-for-go/

Documentation

Overview

Package middleware - HTTP middleware

https://github.com/justinas/alice

Basic example:

package main

import (
   "github.com/nbari/violetear"
   "github.com/nbari/violetear/middleware"
   "log"
   "net/http"
)

func commonHeaders(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
         w.Header().Set("X-app-Version", "1.0")
        next.ServeHTTP(w, r)
    })
}

func middlewareOne(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
     log.Println("Executing middlewareOne")
        next.ServeHTTP(w, r)
        log.Println("Executing middlewareOne again")
    })
}

func main() {
    router := violetear.New()

    stdChain := middleware.New(commonHeaders, middlewareOne)

    router.Handle("/", stdChain.ThenFunc(catchAll), "GET,HEAD")

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

Index

• type Chain
  • func New(constructors ...Constructor) Chain
  • func (c Chain) Append(constructors ...Constructor) Chain
  • func (c Chain) Extend(chain Chain) Chain
  • func (c Chain) Then(h http.Handler) http.Handler
  • func (c Chain) ThenFunc(fn http.HandlerFunc) http.Handler
• type Constructor

Types

type Chain

type Chain struct {
	// contains filtered or unexported fields
}

Chain acts as a list of http.Handler constructors.

func New

func New(constructors ...Constructor) Chain

New creates a new chain

func (Chain) Append

func (c Chain) Append(constructors ...Constructor) Chain

Append extends a chain, adding the specified constructors as the last ones in the request flow.

Append returns a new chain, leaving the original one untouched.

stdChain := middleware.New(m1, m2)
extChain := stdChain.Append(m3, m4)
// requests in stdChain go m1 -> m2
// requests in extChain go m1 -> m2 -> m3 -> m4

func (Chain) Extend

func (c Chain) Extend(chain Chain) Chain

Extend extends a chain by adding the specified chain as the last one in the request flow.

Extend returns a new chain, leaving the original one untouched.

stdChain := middleware.New(m1, m2)
ext1Chain := middleware.New(m3, m4)
ext2Chain := stdChain.Extend(ext1Chain)
// requests in stdChain go  m1 -> m2
// requests in ext1Chain go m3 -> m4
// requests in ext2Chain go m1 -> m2 -> m3 -> m4

Another example:

 aHtmlAfterNosurf := middleware.New(m2)
	aHtml := middleware.New(m1, func(h http.Handler) http.Handler {
		csrf := nosurf.New(h)
		csrf.SetFailureHandler(aHtmlAfterNosurf.ThenFunc(csrfFail))
		return csrf
	}).Extend(aHtmlAfterNosurf)
		// requests to aHtml hitting nosurfs success handler go m1 -> nosurf -> m2 -> target-handler
		// requests to aHtml hitting nosurfs failure handler go m1 -> nosurf -> m2 -> csrfFail

func (Chain) Then

func (c Chain) Then(h http.Handler) http.Handler

Then chains the middleware and returns the final http.Handler.

New(m1, m2, m3).Then(h)

is equivalent to:

m1(m2(m3(h)))

Then() treats nil as http.DefaultServeMux.

func (Chain) ThenFunc

func (c Chain) ThenFunc(fn http.HandlerFunc) http.Handler

ThenFunc works identically to Then, but takes a HandlerFunc instead of a Handler.

The following two statements are equivalent:

c.Then(http.HandlerFunc(fn))
c.ThenFunc(fn)

ThenFunc provides all the guarantees of Then.

type Constructor

type Constructor func(http.Handler) http.Handler

Constructor pattern for all middleware