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Question

当我尝试在我的应用程序上查看页面时，我收到错误

尝试在StatController.php上的第38行获取非对象的属性

研究，这个错误意味着试图获得一个不存在的对象或数据。（待修正）。

但我的问题是，当应用程序的数据库没有任何数据时，联系人页面（查看联系人）也不显示错误，即使联系人表也是空的。

当我尝试在新用户登录时访问主页时，可能导致此错误的原因是什么？

StatController

public function home(Request $request) 
{
     $surveys = Survey::where('user_id', Auth::user()->id)->orderBy('created_at','DESC')->first();
     $respondent = Invite::where('user_id', Auth::user()->id)->where('survey_id', $surveys->id)->count();
     $answers = Invite::where('user_id', Auth::user()->id)->where('link_answered', 1)->where('survey_id', $surveys->id)->count();
     $yet_to_respond = Invite::where('user_id', Auth::user()->id)->where('link_clicked', 1)->where('survey_id', $surveys->id)->count();
     $no_response = Invite::where('user_id', Auth::user()->id)->where('link_clicked', 0)->where('survey_id', $surveys->id)->count();

     return view('home', compact('surveys','respondent','yet_to_respond','no_response','answers'));
}

的ContactController

public function index()
{
    $contacts = Contact::where('user_id', Auth::user()->id)->get();
    return view('contact.index',compact('contact'));
}

Answer 1

问题是$surveys返回null，所以你必须在访问某个属性之前检查它：

public function home(Request $request) 
{
    $respondent = null;
    $answers = null;
    $yet_to_respond = null;
    $no_response = null;

    $surveys = Survey::where('user_id', Auth::user()->id)->orderBy('created_at','DESC')->first();
    if($surveys){
        $respondent = Invite::where('user_id', Auth::user()->id)->where('survey_id', $surveys->id)->count();
        $answers = Invite::where('user_id', Auth::user()->id)->where('link_answered', 1)->where('survey_id', $surveys->id)->count();
        $yet_to_respond = Invite::where('user_id', Auth::user()->id)->where('link_clicked', 1)->where('survey_id', $surveys->id)->count();
        $no_response = Invite::where('user_id', Auth::user()->id)->where('link_clicked', 0)->where('survey_id', $surveys->id)->count();     
    }

    return view('home', compact('surveys','respondent','yet_to_respond','no_response','answers'));
}

另一种方法是使用optional()方法，而不是使用$surveys->id，您将使用optional($surveys)->id

可选函数接受任何参数，并允许您访问该对象的属性或调用方法。如果给定对象为null，则属性和方法将返回null而不是导致错误：

Answer 2

由于@Luis为您提供了正确答案，这是改善代码的另一种方法，只需拨打Invite一次，然后过滤掉。

public function home(Request $request) 
{
     $surveys = Survey::where('user_id', Auth::user()->id)->orderBy('created_at','DESC')->first();
     $invites = collect([]);
     if($surveys){
        $invites = Invite::where('user_id', \Auth::id())->get();
     }
     $respondent = $invites->where('survey_id', $surveys->id ?? 0)->count();
     $answers = $invites->where('link_answered', 1)->where('survey_id', $surveys->id ?? 0)->count();
     $yet_to_respond = $invites->where('link_clicked', 1)->where('survey_id', $surveys->id ?? 0)->count();
     $no_response = $invites->where('link_clicked', 0)->where('survey_id', $surveys->id ?? 0)->count();
     return view('home', compact('surveys','respondent','yet_to_respond','no_response','answers'));
}

Answer 3

正如@Luis所提到的，错误是因为您尝试访问null上的属性，因为如果找不到记录，first方法会返回null。

有一种方法是@Luis在答案中提到检查null或使用optional帮助

要在下面添加答案，请参阅如何使用Eloquent

实现相同目标

使用关系

在Survey模型中添加以下关系

public function invitations()
{
    return $this->hasMany(\App\Invite::class);
}

public function responded()
{
    return $this->invitations()
                ->where('link_answered', 1);
}

public function pending()
{
    return $this->invitations()
                ->where('link_clicked', 1);
}

public function unseen()
{
    return $this->invitations()
                ->where('link_clicked', 0);
}

在StatController

中

public function home(Request $request) 
{
    $survey = Survey::withCount(['invitations', 'responded', 'pending', 'unseen'])
                    ->where('user_id', Auth::user()->id)
                    ->orderBy('created_at','DESC')
                    ->first();
    return view('home', compact('survey'));
}

然后在您的视图中，您可以使用

获取计数

Invitations count: {{ $survey->invitations_count }}
Responded count: {{ $survey->responded_count }}
Pending count: {{ $survey->pending_count }}
Unseen count: {{ $survey->unseen_count }}

此外，如果您愿意，可以稍微清理现有代码。

public function home(Request $request)
{
    $respondent = 0;
    $answers = 0;
    $yet_to_respond = 0;
    $no_response = 0;

    $survey = Survey::where('user_id', Auth::user()->id)
                    ->orderBy('created_at','DESC')->first();

    if ($survey) {
        $invitationQuery = Invite::where('user_id', Auth::user()->id)
                                 ->where('survey_id', $survey->id);

        $respondent = $invitationQuery->count();
        $answers = with(clone $invitationQuery)->where('link_answered', 1)
                                               ->count();
        $yet_to_respond = with(clone $invitationQuery)->where('link_clicked', 1)
                                                      ->count();
        $no_response = with(clone $invitationQuery)->where('link_clicked', 0)
                                                   ->count();
    }

    return view('home', compact('survey','respondent','yet_to_respond','no_response','answers'));
}

试图获得非对象的属性 - Laravel 5.6

3 个答案:

使用关系