Laravel 5：每次使用Auth :: user（）都会查询数据库吗？

如果你看一下SessionGuard.php文件中Illuminate\Auth，你会看到它是用来检索当前已验证用户的方法user()：

/** 
* Get the currently authenticated user. 
* 
* @return \Illuminate\Contracts\Auth\Authenticatable|null 
*/ 
public function user() 
{ 
    if ($this->loggedOut) { 
     return; 
    } 
    // If we've already retrieved the user for the current request we can just 
    // return it back immediately. We do not want to fetch the user data on 
    // every call to this method because that would be tremendously slow. 
    if (! is_null($this->user)) { 
     return $this->user; 
    } 
    $id = $this->session->get($this->getName()); 
    // First we will try to load the user using the identifier in the session if 
    // one exists. Otherwise we will check for a "remember me" cookie in this 
    // request, and if one exists, attempt to retrieve the user using that. 
    $user = null; 
    if (! is_null($id)) { 
     if ($user = $this->provider->retrieveById($id)) { 
      $this->fireAuthenticatedEvent($user); 
     } 
    } 
    // If the user is null, but we decrypt a "recaller" cookie we can attempt to 
    // pull the user data on that cookie which serves as a remember cookie on 
    // the application. Once we have a user we can return it to the caller. 
    $recaller = $this->getRecaller(); 
    if (is_null($user) && ! is_null($recaller)) { 
     $user = $this->getUserByRecaller($recaller); 
     if ($user) { 
      $this->updateSession($user->getAuthIdentifier()); 
      $this->fireLoginEvent($user, true); 
     } 
    } 
    return $this->user = $user; 
} 

//如果我们已经检索到的用户对于当前请求，我们可以立即将其返回。我们不希望每次调用此方法时都要获取用户数据，因为这会非常慢。

if (! is_null($this->user)) { 
     return $this->user; 
    } 

所以，调用user()多次不会对数据库多次调用。

你只会得到1个数据库请求，所以多次使用Auth :: user（）不是问题。

我建议您使用Laravel Debugbar作为应用程序优化的最舒适的方式。