使用 foreach 在数组迭代中获取对象值

Question

在以下非常简化的示例和研究案例中，我们获得了帖子列表和每个帖子的评论数。

但是，我打算只向客户端发送值，即2 ，而不是数组对象[{total: 2}]

有没有一种简化的方法可以用 laravel 做到这一点？

注意：必须使用 DB::select

public function readPosts(Request $request) {     
    $posts = DB::select("SELECT * FROM posts");   

     foreach ($posts as $key => $post) {         
         $idComment = $post->id_comment;             
         $post->nComments = DB::select('SELECT COUNT(id_comment) As total FROM post_comments WHERE id_comment = ? ', [$idComment]); 
     }    

    if($posts){
      return response()->json(['success'=>true, "output"=>$posts);
    }else{
      return response()->json(['success'=>false]);  
    }
}

回复

data:
    0:
      id_post: 1
      post: "post text"
      nComments: [{total:2}]
   1:
      id_post: 2
      post: "post text 2"
      nComments: [{total:1}]

预期的

data:
    0:
      id_post: 1
      post: "post text"
      nComments: 2
    1:
      id_post: 2
      post: "post text 2"
      nComments: 1

Answer 1

您可以使用count()来计算集合计数。

 foreach ($posts as $key => $post) {         
         $idComment = $post->id_comment;             
         $comments = DB::select('SELECT COUNT(id_comment) As total FROM post_comments WHERE id_comment = ? ', [$idComment]); 
         $post->nComments = $comments[0]['total'];
     }    

Answer 2

你可以试试这个

 public function readPosts(Request $request) {     
            $posts = DB::select("SELECT * FROM posts");   

             foreach ($posts as $key => $post) {         
                 $idComment = $post->id_comment; 
                 $total = DB::select('SELECT COUNT(id_comment) As total FROM post_comments WHERE id_comment = ? ', [$idComment]);        
                 $post->nComments = $total[0]['total'];
             }    

            if($posts){
              return response()->json(['success'=>true, "output"=>$posts);
            }else{
              return response()->json(['success'=>false]);  
            }
        }

Answer 3

最干净的方法是使用帖子的关系comments

public function readPosts(Request $request) {     
    $posts = DB::withCount('comments')->get();   

    if($posts){
      return response()->json(['success'=>true, "output"=>$posts);
    }else{
      return response()->json(['success'=>false]);  
    }
}

回复

data:
    0:
      id_post: 1
      post: "post text"
      comments_count: 2
   1:
      id_post: 2
      post: "post text 2"
      comments_count: 1

另外：这将利用 Eloquent 中的急切加载，结果将更快且性能更高。

Answer 4

我建议你可以使用 Eloquent 和 Eloquent 来获取计数。 但是，您需要重建您的表格，并与您的模型建立关系。

如果你真的想使用DB::select() ，

你可以只使用子查询

$posts = DB::select('
SELECT posts.*, (
    SELECT COUNT(id_comment)  AS total
    FROM post_comments 
    WHERE id_comment = posts.id_comment) AS total
FROM posts')

Answer 5

试试这个简单的

 $posts = Post::withCount('comments');  
 dd($post);