Laravel：属于方法问题

Question

我有称为“名称”和“团队成员”的模型。我在Laravel（v5.8.4）应用程序中将它们与“模型关系”相关联。这些表还通过数据库中的主键和外键约束进行连接。

错误：

Symfony\Component\Debug\Exception\FatalErrorException thrown with message "Method Illuminate\View\View::__toString() must not throw an exception, caught ErrorException: Trying to get property of non-object (View: F:\Files\Programming\Web\PHP\wamp\www\Php\Projects\MUC028-CodeLiver128\Laravel\resources\views\administrator\team-members\elements\_grid.blade.php)"

Stacktrace:
#0 Symfony\Component\Debug\Exception\FatalErrorException in F:\Files\Programming\Web\PHP\wamp\www\Php\Projects\MUC028-CodeLiver128\Laravel\storage\framework\views\be1013e7ebf4b2a7b40bda946160daf4cc4fe012.php:0

型号：

class Designations extends Model
{
    /**
     * Relationships
     */
    public function teamMembers()
    {
        return $this->hasMany(TeamMembers::class);
    }

    ...
}

class TeamMembers extends Model
{
    /**
     * Relationships
     */
    public function designation()
    {
        return $this->belongsTo(Designations::class);
    }

    ...
}

表格：

Designations:
    id
    title
    ...

TeamMembers:
    id
    designations_id
    full_name
    ...

查看：

@foreach ($data as $key => $value)
    {!! $value->designation->title !!}
@endforeach

我尝试使用模型名称（Designations）代替类Designations::class，但它不起作用。我总是遇到同样的错误。