猫鼬聚合查找管道不起作用

问题描述

有谁知道为什么这种聚合仅匹配帖子，却不填充评论？

我需要评论集合中的用户评论，但只有空管道返回评论

Post.aggregate(...)

[
        {
            "$match": {
                "author": ObjectId(...)
            }
        },{
            "$lookup": {
                "from": "comments","let": {
                    "postID": "$post","isHiden": "$isHiden"
                },"pipeline": [
                    {
                        "$match": {
                            "$expr": {
                                "$and": [
                                    {
                                        "$eq": [
                                            "$_id","$$postID"
                                        ]
                                    },{
                                        "$eq": [
                                            "$$isHiden",0
                                        ]
                                    }
                                ]
                            }
                        }
                    }
                ],"as": "comments"
            }
        }
    ]

评论对象包含

{
  "_id": "5f7de8491af5c0e246d42609","isHiden": false,"text": "...","post": "5f7de8491af5c0e246d42605"
}

帖子模型是

{
  "_id": "5f7de8491af5c0e246d42605","title": "Corporate Web Coordinator","body": "...","author": "5f7de8491af5c0e246d42602"
  }
}

我想得到像这样的结果

       {
            "_id": "5f7de8491af5c0e246d42605","confirm_status": "pending","title": "Dynamic Marketing Supervisor","author": "5f7de8491af5c0e246d42604","comments": [
                  { "_id": "5f7de8491af5c0e246d42609","post": "5f7de8491af5c0e246d42605" }
             ]
        }

我尝试了一切，但无济于事...

我将不胜感激

解决方法

问题出在您的查询中，

• post字段出现在注释表中，并且您使用了_id，因此应为$post，
• 内部管道字段isHiden在发布表中不存在，您正在let中定义该字段，

    $lookup: {
      from: "comments",let: { postID: "$_id" },pipeline: [
        {
          $match: {
            $expr: [
              {
                $eq: [
                  "$$postID","$post"
                ]
              }
            ],isHiden: false
          }
        }
      ],as: "comments"
    }

Playground