ErrorException未定义的偏移量：0

Question

我是Laravel框架的新手。 我尝试在我的PC上运行我的朋友项目，并在打开某个菜单时出现错误，并且在浏览器中运行代码时，它显示ErrorException (E_NOTICE) Undefined offset: 0 。 我该怎么做才能解决此错误？

这是处理菜单的控制器

public function getViewPesananCust(){
        $userId = Auth::user()->id;
        $data['transaksi'] = Transaction::select('*', 'transaction.id as id_transaksi')
        ->join('users as pemesan', 'pemesan.id', 'transaction.id_user')
        ->where('transaction.id_user', '=', $userId)
        ->orderBy('timestamp', 'DESC')->get();
        $data['rating_user'] = array();
        $x = Transaction::where('id_user', $userId)->where('status_transaksi', 1)->orderBy('timestamp', 'DESC')->get();
        $a = array();
        foreach($x as $y) {
            $z = Transaksi::where('id_transaksi', $y['id_transaksi'])->get()[0];
            array_push($a, $z);
        }
        $b = array();
        foreach($a as $y) {
            $z = Menu::where('id',$y['id_menu'])->get()[0];
            array_push($b, $z);
        }
        $c = array();
        foreach($b as $y) {
            $z = Rating::where('id_menu', $y['id'])->get()[0];
            array_push($c, $z);
        }
        $data['rating_user'] = $c;

        return view('pesanan', $data);
    }

Answer 1

因为您的第一个循环在集合上，所以它的循环很好，但是对于第二个循环，您需要使用键值对，因为它在关联数组上循环。

       foreach($a as $key=>$value) {
          $z = Menu::where('id',$value['id_menu'])->get()[0];
          array_push($b, $z);
       }

Answer 2

查询数据库可能返回空结果。 使用前，您需要检查查询结果中存在的数据。

   public function getViewPesananCust(){
        $userId = Auth::user()->id;
        $data['transaksi'] = Transaction::select('*', 'transaction.id as id_transaksi')
        ->join('users as pemesan', 'pemesan.id', 'transaction.id_user')
        ->where('transaction.id_user', '=', $userId)
        ->orderBy('timestamp', 'DESC')->get();
        $data['rating_user'] = array();
        $x = Transaction::where('id_user', $userId)->where('status_transaksi', 1)->orderBy('timestamp', 'DESC')->get();
        $a = array();
        foreach($x as $y) {
            // check empty records
            $d1 = Transaksi::where('id_transaksi', $y['id_transaksi'])->get();
            if($d1 && count(d1) > 0){
                $z = $d1[0];
                array_push($a, $z);
            }
        }
        $b = array();
        foreach($a as $y) {
            $d2 = Menu::where('id',$y['id_menu'])->get();
            // check empty records
            if($d2 && count(d2) > 0){
                $z = $d2[0];
                array_push($b, $z);
            }
        }
        $c = array();
        foreach($b as $y) {                
            $d3 = Menu::where('id',$y['id_menu'])->get();
            // check empty records
            if($d3 && count(d3) > 0){
                $z = $d3[0];
                array_push($c, $z);
            }
        }
        $data['rating_user'] = $c;

        return view('pesanan', $data);
    }