php小编鱼仔为您介绍一种强大的技术：有条件地执行多个模板。在开发网站时，我们常常需要根据不同的条件动态地加载不同的模板文件，这就是有条件地执行多个模板的应用场景。通过使用这种技术，我们可以根据用户的登录状态、权限等条件来动态地加载相应的模板文件，从而实现更灵活、个性化的网站界面。这种技术不仅提高了网站的可扩展性和可维护性，还能为用户提供更好的使用体验。在本文中，我们将详细介绍如何使用php实现有条件地执行多个模板的方法，帮助您更好地应用于实际项目中。
问题内容
我有一个具有两种视图的网页，一种用于匿名用户，一种用于管理员用户。我想仅为管理员用户显示导航栏。对于两种用户类型，其他一切都保持不变。
这是我迄今为止尝试过的
main.go
package main
import (
"log"
"net/http"
"text/template"
"github.com/julienschmidt/httprouter"
)
func basicauth(h httprouter.handle, requireduser, requiredpassword string) httprouter.handle {
return func(w http.responsewriter, r *http.request, ps httprouter.params) {
// get the basic authentication credentials
user, password, hasauth := r.basicauth()
if hasauth && user == requireduser && password == requiredpassword {
// delegate request to the given handle
h(w, r, ps)
} else {
// request basic authentication otherwise
w.header().set("www-authenticate", "basic realm=restricted")
http.error(w, http.statustext(http.statusunauthorized), http.statusunauthorized)
}
}
}
func anonymous(w http.responsewriter, r *http.request, _ httprouter.params) {
t, err := template.parsefiles("index.html")
if err != nil {
log.fatalln(err)
}
err = t.execute(w, map[string]string{"name": "anonymous"})
if err != nil {
log.fatalln(err)
}
}
func admin(w http.responsewriter, r *http.request, _ httprouter.params) {
t, err := template.parsefiles("index.html", "admin.html")
if err != nil {
log.fatalln(err)
}
err = t.execute(w, map[string]string{"name": "admin"})
if err != nil {
log.fatalln(err)
}
}
func main() {
user := "admin"
pass := "1234"
router := httprouter.new()
router.get("/", anonymous)
router.get("/admin/", basicauth(admin, user, pass))
log.fatal(http.listenandserve(":8080", router))
}
index.html
<!doctype html>
<html lang="en">
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>{{ .name }}</title>
<link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet">
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.bundle.min.js"></script>
<script src="https://code.jquery.com/jquery-3.6.4.min.js"></script>
<script>
function counter() {
document.getelementbyid("x").innerhtml = "x: " + document.queryselectorall('.x').length;
document.getelementbyid("y").innerhtml = "y: " + document.queryselectorall('.y').length;
document.getelementbyid("z").innerhtml = "z: " + document.queryselectorall('.z').length;
}
</script>
</head>
<body onload="counter()">
{{ template "dashboard" }}
<nav class="navbar fixed-bottom">
<div class="container-fluid nav-justified">
<span id="x" class="navbar-brand nav-item"></span>
<span id="y" class="navbar-brand nav-item"></span>
<span id="z" class="navbar-brand nav-item"></span>
</div>
</nav>
</body>
</html>
admin.html
{{ define "dashboard" }}
<nav class="navbar">
<div class="container-fluid nav-justified">
<span class="nav-item">
<a class="navbar-brand" href="/a">a</a>
</span>
<span class="nav-item">
<a class="navbar-brand" href="/b">b</a>
</span>
<span class="nav-item">
<a class="navbar-brand" href="/c">c</a>
</span>
</div>
</nav>
{{ end }}
我的假设是，因为我在为匿名用户执行模板时没有传入 admin.html 模板，所以仪表板模板不会被解析。但是，我遇到了这个错误：
template: index.html:18:14: executing "index.html" at <{{template "dashboard"}}>: template "dashboard" not defined
如何解决这个问题，或者有更好的方法吗？
解决方法
使用 if 操作有条件地渲染 dashboard 模板：
{{ if eq .name "admin" }} {{ template "dashboard" }} {{ end }}
实践是只解析模板一次，而不是在每个请求时都解析它：
package main
import (
"log"
"net/http"
"sync"
"text/template"
"github.com/julienschmidt/httprouter"
)
func BasicAuth(h httprouter.Handle, requiredUser, requiredPassword string) httprouter.Handle {
return func(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
user, password, hasAuth := r.BasicAuth()
if hasAuth && user == requiredUser && password == requiredPassword {
h(w, r, ps)
} else {
w.Header().Set("WWW-Authenticate", "Basic realm=Restricted")
http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
}
}
}
func Anonymous(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
err := tmpl.Execute(w, map[string]string{"Name": "Anonymous"})
if err != nil {
log.Fatalln(err)
}
}
func Admin(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
err := tmpl.Execute(w, map[string]string{"Name": "Admin"})
if err != nil {
log.Fatalln(err)
}
}
var (
tmpl *template.Template
tmplOnce sync.Once
)
func main() {
user := "admin"
pass := "1234"
tmplOnce.Do(func() {
tmpl = template.Must(template.ParseFiles("index.html", "admin.html"))
})
router := httprouter.New()
router.GET("/", Anonymous)
router.GET("/admin/", BasicAuth(Admin, user, pass))
log.Fatal(http.ListenAndServe(":8080", router))
}
