如何在猫鼬中将对象字段作为数组获取？

Question

您好，我有一个如下所示的 mongoose 架构，

const followingFollowersSchema = mongoose.Schema({
  follower: {
     type: mongoose.Schema.ObjectId,
     ref: 'User'
  },
  following: {
     type: mongoose.Schema.ObjectId,
     ref: 'User'
  },
});

我在调用时创建了一个路由，它过滤当前登录用户正在关注的所有用户并显示以下输出，

{
  "status": "success",
  "results": 1,
  "data": {
    "following": [
            {
              "_id": "5ef4cd0205070d87156e19da",
              "following": {
                  "_id": "5eeb92d69fceed6d91ad5743",
                  "name": "X Y"
            }
          }
      ]
  }
}

但我想显示这样的输出，

{
  "status": "success",
  "results": 1,
  "data": {
      "following": [
          {
              "_id": "5eeb92d69fceed6d91ad5743",
              "name": "X Y"
          }
      ]
  }
}

我怎样才能做到这一点？任何帮助将不胜感激。

Answer 1

您可以使用$addFields 替换现有字段并使用$map 转换内部数组：

let result = Model.aggregate([
    {
        $addFields: {
            "data.following": {
                $map: {
                    input: "$data.following",
                    in: "$$this.following"
                }
            }
        }
    }
])

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