Example of a minimal wiki web app with only Go's standard library

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>

main.go

package main

import (
	"errors"
	"html/template"
	"log"
	"net/http"
	"os"
	"regexp"
)

var templates = template.Must(template.ParseFiles("edit.html", "view.html"))
var validPath = regexp.MustCompile("^/(edit|save|view)/([a-zA-Z0-9]+)$")

type Page struct {
	Title string
	Body  []byte
}

func (p *Page) Save() error {
	fileName := p.Title + ".txt"
	return os.WriteFile(fileName, p.Body, 0600)
}

func LoadPage(title string) (*Page, error) {
	fileName := title + ".txt"

	body, err := os.ReadFile(fileName)
	if err != nil {
		return nil, err
	}

	return &Page{Title: title, Body: body}, nil
}

func GetTitle(writer http.ResponseWriter, request *http.Request) (string, error) {
	match := validPath.FindStringSubmatch(request.URL.Path)
	if match == nil {
		http.NotFound(writer, request)
		return "", errors.New("invalid Page Title")
	}
	return match[2], nil // The title is the second subexpression.
}

func ViewHandler(writer http.ResponseWriter, request *http.Request) {
	title, err := GetTitle(writer, request)
	if err != nil {
		return
	}

	page, err := LoadPage(title)
	if err != nil {
		http.Redirect(writer, request, "/edit/"+title, http.StatusFound)
		return
	}

	templates.ExecuteTemplate(writer, "view.html", page)
}

func EditHandler(writer http.ResponseWriter, request *http.Request) {
	title, err := GetTitle(writer, request)
	if err != nil {
		return
	}

	page, err := LoadPage(title)
	if err != nil {
		page = &Page{Title: title}
	}

	templates.ExecuteTemplate(writer, "edit.html", page)
}

func SaveHandler(writer http.ResponseWriter, request *http.Request) {
	title, err := GetTitle(writer, request)
	if err != nil {
		return
	}

	body := request.FormValue("body")
	page := &Page{Title: title, Body: []byte(body)}

	err = page.Save()
	if err != nil {
		http.Error(writer, err.Error(), http.StatusInternalServerError)
		return
	}

	http.Redirect(writer, request, "/view/"+title, http.StatusFound)
}

func main() {
	http.HandleFunc("/view/", ViewHandler)
	http.HandleFunc("/edit/", EditHandler)
	http.HandleFunc("/save/", SaveHandler)

	log.Fatal(http.ListenAndServe(":6969", nil))
}

view.html

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

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

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