Go -Web application-

◼︎Web application

Writing Web Applications - The Go Programming Language

◼︎出力

割愛

◼︎コード

今回は詳細画面->編集（新規）->登録の画面を作成

package main

import (
	"fmt"
	"html/template"
	"io/ioutil"
	"log"
	"net/http"
	"regexp"
)

type Page struct {
	Title string
	Body  []byte
}

func (p *Page) save() error {
	filename := p.Title + ".txt"
	return ioutil.WriteFile(filename, p.Body, 0600)
}

func loadPage(title string) (*Page, error) {
	filename := title + ".txt"
	body, err := ioutil.ReadFile(filename)
	if err != nil {
		return nil, err
	}
	return &Page{Title: title, Body: body}, nil
}

// テンプレートはキャッシュしておく
var templates = template.Must(template.ParseFiles("edit.html", "view.html"))
func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) {
	// キャッシュしたテンプレートを取得
	if err := templates.ExecuteTemplate(w, tmpl+".html", p); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}
}

// http://localhost:7777/view/test
func viewTHandler(w http.ResponseWriter, r *http.Request, title string) {
	p, err := loadPage(title)
	if err != nil {
		http.Redirect(w, r, "/edit/"+title, http.StatusFound)
		return
	}
	renderTemplate(w, "view", p)
}

// http://localhost:7777/edit/test
func editTHandler(w http.ResponseWriter, r *http.Request, title string) {
	p, err := loadPage(title)
	if err != nil {
		p = &Page{Title: title}
	}
	renderTemplate(w, "edit", p)
}

// 編集後の処理
func saveTHandler(w http.ResponseWriter, r *http.Request, title string) {
	body := r.FormValue("body")
	p := &Page{Title: title, Body: []byte(body)}
	err := p.save()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	http.Redirect(w, r, "view"+title, http.StatusFound)
}

// URLの解析を行う
var validPath = regexp.MustCompile("^/(edit|save|view)/([a-zA-Z0-9]+)$")
func makeHandler(fn func(http.ResponseWriter, *http.Request, string)) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		m := validPath.FindStringSubmatch(r.URL.Path)
		if m == nil {
			http.NotFound(w, r)
			return
		}
		fn(w, r, m[2])
	}
}

func main() {
    // serverの起動
    http.HandleFunc("/view/", makeHandler(viewTHandler))
    http.HandleFunc("/edit/", makeHandler(editTHandler))
    http.HandleFunc("/save/", makeHandler(saveTHandler))
    log.Fatal(http.ListenAndServe(":7777", nil))
}

view.html

<h1>{{.Title}}</h1>

<p>[<a href="/edit/{{.Title}}">Edit</a>]</p>

<div>{{printf "%s" .Body}}</div>

edit.html

<h1>Editing {{.Title}}</h1>

<form action="/save/{{.Title}}" method="POST">
    <div>
        <textarea name="body" rows="20" cols="80">{{printf "%s" .Body}}</textarea>
    </div>
    <div>
        <input type="submit" value="Save">
    </div>
</form>

test.txt

this is a testpage.