dd 可以看到数据，但是无法读取，是为什么

上代码：

$user_result = Auth::user()->topicanswers->where('topic_id',$this->id);
dd($user_result);

结果：

Illuminate\Database\Eloquent\Collection {#842 ▼
  #items: array:1 [▼
    0 => App\Models\TopicAnswer {#869 ▼
      #fillable: array:1 [▶]
      #connection: "mysql"
      #table: "topic_answers"
      #primaryKey: "id"
      #keyType: "int"
      +incrementing: true
      #with: []
      #withCount: []
      #perPage: 15
      +exists: true
      +wasRecentlyCreated: false
      #attributes: array:6 [▼
        "id" => 1
        "user_id" => 1
        "topic_id" => 2
        "result" => 2
        "created_at" => "2020-02-29 01:19:33"
        "updated_at" => "2020-02-29 01:19:35"
      ]
      #original: array:6 [▶]
      #changes: []
      #casts: []
      #dates: []
      #dateFormat: null
      #appends: []
      #dispatchesEvents: []
      #observables: []
      #relations: []
      #touches: []
      +timestamps: true
      #hidden: []
      #visible: []
      #guarded: array:1 [▶]
    }
  ]
}

继续，dd($user_result->result)报错:

Property [result] does not exist on this collection instance. (View: D:\Didongni\App\idongni\resources\views\mobile\topics\index.blade.php)

这是为什么，为什么读取不到2

好，再继续，dd(collect($user_result))，结果：

Illuminate\Support\Collection {#732 ▼
  #items: array:1 [▼
    0 => App\Models\TopicAnswer {#869 ▼
      #fillable: array:1 [▶]
      #connection: "mysql"
      #table: "topic_answers"
      #primaryKey: "id"
      #keyType: "int"
      +incrementing: true
      #with: []
      #withCount: []
      #perPage: 15
      +exists: true
      +wasRecentlyCreated: false
      #attributes: array:6 [▼
        "id" => 1
        "user_id" => 1
        "topic_id" => 2
        "result" => 2
        "created_at" => "2020-02-29 01:19:33"
        "updated_at" => "2020-02-29 01:19:35"
      ]
      #original: array:6 [▶]
      #changes: []
      #casts: []
      #dates: []
      #dateFormat: null
      #appends: []
      #dispatchesEvents: []
      #observables: []
      #relations: []
      #touches: []
      +timestamps: true
      #hidden: []
      #visible: []
      #guarded: array:1 [▶]
    }
  ]
}

这下总可以了吧，但是dd(collect($user_result)->result)依然报错：

Property [result] does not exist on this collection instance. (View: D:\Didongni\App\idongni\resources\views\mobile\topics\index.blade.php)

最后，$user_result = Auth::user()->topicanswers->where('topic_id',$this->id)[0]->result;，这样就可以，我记得不需要用下标啊，难道我迷糊了？？？