github.com/varialus/godfly@v0.0.0-20130904042352-1934f9f095ab/doc/articles/wiki/final-noclosure.go (about)

     1  // Copyright 2010 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package main
     6  
     7  import (
     8  	"errors"
     9  	"html/template"
    10  	"io/ioutil"
    11  	"net/http"
    12  	"regexp"
    13  )
    14  
    15  type Page struct {
    16  	Title string
    17  	Body  []byte
    18  }
    19  
    20  func (p *Page) save() error {
    21  	filename := p.Title + ".txt"
    22  	return ioutil.WriteFile(filename, p.Body, 0600)
    23  }
    24  
    25  func loadPage(title string) (*Page, error) {
    26  	filename := title + ".txt"
    27  	body, err := ioutil.ReadFile(filename)
    28  	if err != nil {
    29  		return nil, err
    30  	}
    31  	return &Page{Title: title, Body: body}, nil
    32  }
    33  
    34  func viewHandler(w http.ResponseWriter, r *http.Request) {
    35  	title, err := getTitle(w, r)
    36  	if err != nil {
    37  		return
    38  	}
    39  	p, err := loadPage(title)
    40  	if err != nil {
    41  		http.Redirect(w, r, "/edit/"+title, http.StatusFound)
    42  		return
    43  	}
    44  	renderTemplate(w, "view", p)
    45  }
    46  
    47  func editHandler(w http.ResponseWriter, r *http.Request) {
    48  	title, err := getTitle(w, r)
    49  	if err != nil {
    50  		return
    51  	}
    52  	p, err := loadPage(title)
    53  	if err != nil {
    54  		p = &Page{Title: title}
    55  	}
    56  	renderTemplate(w, "edit", p)
    57  }
    58  
    59  func saveHandler(w http.ResponseWriter, r *http.Request) {
    60  	title, err := getTitle(w, r)
    61  	if err != nil {
    62  		return
    63  	}
    64  	body := r.FormValue("body")
    65  	p := &Page{Title: title, Body: []byte(body)}
    66  	err = p.save()
    67  	if err != nil {
    68  		http.Error(w, err.Error(), http.StatusInternalServerError)
    69  		return
    70  	}
    71  	http.Redirect(w, r, "/view/"+title, http.StatusFound)
    72  }
    73  
    74  func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) {
    75  	t, err := template.ParseFiles(tmpl + ".html")
    76  	if err != nil {
    77  		http.Error(w, err.Error(), http.StatusInternalServerError)
    78  		return
    79  	}
    80  	err = t.Execute(w, p)
    81  	if err != nil {
    82  		http.Error(w, err.Error(), http.StatusInternalServerError)
    83  	}
    84  }
    85  
    86  const lenPath = len("/view/")
    87  
    88  var titleValidator = regexp.MustCompile("^[a-zA-Z0-9]+$")
    89  
    90  func getTitle(w http.ResponseWriter, r *http.Request) (title string, err error) {
    91  	title = r.URL.Path[lenPath:]
    92  	if !titleValidator.MatchString(title) {
    93  		http.NotFound(w, r)
    94  		err = errors.New("Invalid Page Title")
    95  	}
    96  	return
    97  }
    98  
    99  func main() {
   100  	http.HandleFunc("/view/", viewHandler)
   101  	http.HandleFunc("/edit/", editHandler)
   102  	http.HandleFunc("/save/", saveHandler)
   103  	http.ListenAndServe(":8080", nil)
   104  }