Go Web Examples

https://gowebexamples.com/

Basic

package main

import (
    "fmt"
    "net/http"
)

func main() {
    http.HandleFunc(
        "/", 
        func(w http.ResponseWriter, r *http.Request) { // 1. A request handler
            fmt.Fprintf(w, "Hello, you've requested: %s\n", r.URL.Path)
        }
    ) // 2. Registering a handler to the default HTTP Server

    http.ListenAndServe(":80", nil) // 3. start a HTTP server and listen for connections on port 80.
}

HTTP server

A basic HTTP server:

1. process dynamic requests.

2. serve static assets.

3. listen on a specific port to be able to accept connections from the internet.

package main

import (
    "fmt"
    "net/http"
)

func main() {
    http.HandleFunc(
        "/", 
        func (w http.ResponseWriter, r *http.Request) {
            fmt.Fprintf(w, "Welcome to my website!")
        }
    )

    // serve static assets
    fs := http.FileServer(http.Dir("static/")) // define file server
    http.Handle("/static/", http.StripPrefix("/static/", fs)) // 1. assign URL; 2. to serve files correctly, we need to strip away a part of the url path.

    http.ListenAndServe(":80", nil)
}

You can read GET parameters with r.URL.Query().Get("token") or POST form parameters with r.FormValue("email").

Routing

need gorilla/mux

$ go get -u github.com/gorilla/mux

package main

import (
    "fmt"
    "net/http"
    "github.com/gorilla/mux"
)

func main() {
    router := mux.NewRouter() // create a new request router
    router.HandleFunc(
        "/books/{title}/page/{page}", 
        func(w http.ResponseWriter, r *http.Request) {
            vars := mux.Vars(r) // get the data from these segments
            title := vars["title"]
            page := vars["page"]

            fmt.Fprintf(w, "You've requested the book: %s on page %s\n", title, page)
        }
    )

    http.ListenAndServe(":80", router) // nil = use the default router; here, we use 'router'
}

Templates

automatic escaping = no need to worry about about XSS attacks.

{{.}}The dot is called the pipeline and the root element of the data.

package main

import (
    "html/template"
    "net/http"
)

type Todo struct {
    Title string
    Done  bool
}

type TodoPageData struct {
    PageTitle string
    Todos     []Todo
}

func main() {
    tmpl := template.Must(template.ParseFiles("layout.html")) 
    // or: tmpl, err := template.ParseFiles("layout.html")

    data := TodoPageData{
        PageTitle: "My TODO list",
        Todos: []Todo{
            {Title: "Task 1", Done: false},
            {Title: "Task 2", Done: true},
            {Title: "Task 3", Done: true},
        },
    }

    http.HandleFunc(
        "/", 
        func(w http.ResponseWriter, r *http.Request) {
            tmpl.Execute(w, data) // header: Content-Type: text/html; charset=utf-8
        }
    )

    http.ListenAndServe(":80", nil)
}

<h1>{{.PageTitle}}<h1>
<ul>
    {{range .Todos}}
        {{if .Done}}
            <li class="done">{{.Title}}</li>
        {{else}}
            <li>{{.Title}}</li>
        {{end}}
    {{end}}
</ul>

Assets and Files