如何返回单个对象（mongoose/mongoDB）

问：

我把这些数据存储在数据库中。

{
  "_id": "62fa5aa25778ec97bc6ee231",
  "user": "62f0eb5ebebd0f236abcaf9d",
  "name": "Marketing Plan",
  "columns": [
    {
      "name": "todo",
      "_id": "62fa5aa25778ec97bc6ee233",
      "tasks": [
        {
          "title": "Task Four testing 2",
          "description": "This is task four",
          "subtasks": [
            {
              "name": "wash dshes test",
              "completed": false,
              "_id": "62ff74bfe80b11ade2d34456"
            },
            {
              "name": "do homework",
              "completed": false,
              "_id": "62ff74bfe80b11ade2d34457"
            }
          ],
          "_id": "62ff74bfe80b11ade2d34455"
        }
      ]
    },
    {
      "name": "doing",
      "_id": "62fa5aa25778ec97bc6ee234",
      "tasks": []
    },
    {
      "name": "done",
      "_id": "62fa5aa25778ec97bc6ee235",
      "tasks": []
    }
  ],
  "__v":0
}

我希望能够返回 id 等于 req.params.id 的单个对象，在本例中为 62ff74bfe80b11ade2d34455。

{
  "title": "Task Four testing 2",
  "description": "This is task four",
  "subtasks": [
    {
      "name": "wash dshes test",
      "completed": false,
      "_id": "62ff74bfe80b11ade2d34456"
    },
    {
      "name": "do homework",
      "completed": false,
      "_id": "62ff74bfe80b11ade2d34457"
    }
  ],
  "_id": "62ff74bfe80b11ade2d34455"
}

我研究了stackoverflow，并遇到了这个潜在的解决方案：Mongoose从实现聚合框架的嵌套数组中检索一个文档。但是当我在 postman 中测试这一点时，没有发出请求。

const getTask = asyncHandler(async (req, res) => {
  const task = await Board.aggregate([
    {
      $match: {
        "columns.tasks._id": req.params.id,
      },
    },
    {
      $project: {
        columns: {
          $first: {
            $filter: {
              input: "$columns.tasks",
              cond: {
                $eq: ["$$this._id", req.params.id],
              },
            },
          },
        },
      },
    },
    {
      $replaceRoot: {
        newRoot: "$columns",
      },
    },
  ]);
});