edit.html

<h1>Editing {{.Title}}</h1>
<form action="/save/{{.Title}}" method="POST">
  <div>
    <textarea name="body" cols="80" rows="20">{{printf "%s" .Body}}</textarea>
  </div>
  <div>
    <input type="submit" value="Save">
  </div>  
</form>

foo.txt

This is a sample Page.

stack trace

2013/06/03 16:02:47 http: panic serving 127.0.0.1:39740: runtime error: invalid memory address or nil pointer dereference
/home/nathan/go/src/pkg/net/http/server.go:589 (0x43fba1)
        _func_004: buf.Write(debug.Stack())
/home/nathan/go/src/pkg/runtime/proc.c:1443 (0x40fafa)
        panic: reflect·call(d->fn, d->args, d->siz);
/home/nathan/go/src/pkg/runtime/runtime.c:128 (0x4105c6)
        panicstring: runtime·panic(err);
/home/nathan/go/src/pkg/runtime/thread_linux.c:199 (0x413418)
        sigpanic: runtime·panicstring("invalid memory address or nil pointer dereference");
/home/nathan/go/src/pkg/html/template/template.go:51 (0x42213f)
        (*Template).Execute: t.nameSpace.mu.Lock()
/home/nathan/Dropbox/code/go/gowiki/wiki.go:36 (0x400eef)
        renderTemplate: t.Execute(w, p)
/home/nathan/Dropbox/code/go/gowiki/wiki.go:42 (0x400f7a)
        viewHandler: renderTemplate(w, "view", p)
/home/nathan/go/src/pkg/net/http/server.go:703 (0x4339ea)
        HandlerFunc.ServeHTTP: f(w, r)
/home/nathan/go/src/pkg/net/http/server.go:941 (0x43483e)
        (*ServeMux).ServeHTTP: mux.handler(r).ServeHTTP(w, r)
/home/nathan/go/src/pkg/net/http/server.go:669 (0x4337fd)
        (*conn).serve: handler.ServeHTTP(w, w.req)
/home/nathan/go/src/pkg/runtime/proc.c:271 (0x40dc00)
        goexit: runtime·goexit(void)

view.html

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

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

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

wiki.go

// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

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

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
}

const lenPath = len("/view/")

func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) {
	t, _ := template.ParseFiles(tmpl + ".html")
	t.Execute(w, p)
}

func viewHandler(w http.ResponseWriter, r *http.Request) {
	title := r.URL.Path[lenPath:]
	p, _ := loadPage(title)
	renderTemplate(w, "view", p)
}

func editHandler(w http.ResponseWriter, r *http.Request) {
	title := r.URL.Path[lenPath:]
	p, err := loadPage(title)
	if err != nil {
		p = &Page{Title: title}
	}
	renderTemplate(w, "edit", p)
}

func main() {
	http.HandleFunc("/view/", viewHandler)
	http.HandleFunc("/edit/", editHandler)
	//http.HandleFunc("/save/", saveHandler)
	http.ListenAndServe(":8080", nil)
}