Malcolm

Malcolm is a stupid simple middleware chaining syntax for Go.

Usage

import github.com/emfrick/malcolm

Call the Then() function on malcolm and pass it middleware of type func(next http.Handler) http.Handler. Call Then() as many times as necessary to chain middleware. Call Create() at the end of the chain to create the middleware chain. Use this chain to wrap your handler of type func (h http.Handler) http.Handler.

Example

Create logging middleware:

func LoggerMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Println("LoggerMiddleware Begin")
		next.ServeHTTP(w, r)
		fmt.Println("LoggerMiddleware End")
	})
}

Create authentication middleware:

func AuthMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Println("AuthMiddleware Begin")
		next.ServeHTTP(w, r)
		fmt.Println("AuthMiddleware End")
	})
}

Create your route handler

func RouteHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Println("RouteHandler Begin")

    // ... Do All The Things

    fmt.Println("RouteHandler End")
}

Wrap your route handler with the middleware

func main() {

    routeHandler := http.HandlerFunc(RouteHandler)

    standardChain := malcom.
                        Then(LoggerMiddleware).
                        Then(AuthMiddleware).
                        Create()

    http.Handle("/route", standardChain(routeHandler))

    http.ListenAndServe(":8080", nil)
}

Log output:

LoggerMiddleware Begin
AuthMiddleware Begin
RouteHandlerBegin
RouteHandlerEnd
AuthMiddleware End
LoggerMiddleware End