# 使用auth()全局辅助和Auth Facade

auth()全局辅助函数是在整个应用内与已认证用户交互最简单的方法。你也可以注入Illuminate\Auth \AuthManager实例获取相同的功能，或者使用Auth facade。

最常见的需求是检测用户是或否登录(如果已经登录auth()->check()将返回true,auth()->guest()如果用户没登录则返回true)。以及获取当前登录的用户(auth()->user(),或者auth()->id()用于获取用户ID，如果用户没登录，这俩方法返回null)。

查看示例9-3，在控制器内使用全局auth()辅助函数。

{% code title="Example 9-3. Sample usage of the auth() global helper in a controller" %}

```php
public function dashboard() {
    if (auth()->guest()) {
        return redirect('sign-up');
    }
    return view('dashboard') ->with('user', auth()->user());
}
```

{% endcode %}

下一章介绍auth系统的幕后，这是有用的但不是特别重要的信息，如果你想查看的话请翻阅231页面的"The Auth Scaffold"


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