Let's Go › Configuration and error handling › Isolating the application routes
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Chapter 3.5.

Isolating the application routes

While we’re refactoring our code there’s one more change worth making.

Our main() function is beginning to get a bit crowded, so to keep it clear and focused I’d like to move the route declarations for the application into a standalone routes.go file, like so:

$ touch cmd/web/routes.go
File: cmd/web/routes.go
package main

import "net/http"

// The routes() method returns a servemux containing our application routes.
func (app *application) routes() *http.ServeMux {
    mux := http.NewServeMux()

    fileServer := http.FileServer(http.Dir("./ui/static/"))
    mux.Handle("GET /static/", http.StripPrefix("/static", fileServer))

    mux.HandleFunc("GET /{$}", app.home)
    mux.HandleFunc("GET /snippet/view/{id}", app.snippetView)
    mux.HandleFunc("GET /snippet/create", app.snippetCreate)
    mux.HandleFunc("POST /snippet/create", app.snippetCreatePost)

    return mux
}

We can then update the main.go file to use this instead:

File: cmd/web/main.go
package main

...

func main() {
    addr := flag.String("addr", ":4000", "HTTP network address")
    flag.Parse()

    logger := slog.New(slog.NewTextHandler(os.Stdout, nil))

    app := &application{
        logger: logger,
    }

    logger.Info("starting server", "addr", *addr)
    
    // Call the new app.routes() method to get the servemux containing our routes,
    // and pass that to http.ListenAndServe().
    err := http.ListenAndServe(*addr, app.routes())
    logger.Error(err.Error())
    os.Exit(1)
}

This is quite a bit neater. The routes for our application are now isolated and encapsulated in the app.routes() method, and the responsibilities of our main() function are limited to: