在聚合中取消选择字段

Question

我编写了一种方法，该方法每月运行一次，并向人们发送进度报告。进行了聚合，现在我需要扩展更多的数据。

在$ profiles展开后，我尝试执行查找，但这会清空最终结果中的字段。

async function(req, res, next) {
  const d = new Date();
  d.setMonth(d.getMonth() - 1);

  const result = await MemoryCard.aggregate([
    {$match: {'updatedAt': {
      $gte: d,
      $lte: new Date(),
    }}},
    {
      $lookup: {
        from: 'users',
        localField: 'owner',
        foreignField: '_id',
        as: 'owner',
      },
    },
    {$unwind: '$owner'},
    {$unwind: '$profiles'},
    {$match: {
      'progress.createdAt': {
        $gte: d,
        $lte: new Date(),
      },
      'progress.file_one': {$eq: true},
      'progress.file_two': {$eq: true},
    }},
    {$unwind: '$progress'},
    {
      $group: {
        '_id': '$_id',
        'owner': {$first: '$owner'},
        'progress': {$addToSet: '$progress'},
        'profiles': {$last: '$profiles'},
      },
    },
    {$unwind: '$profiles'},
    {
      '$project': {
        'owner.email': '$owner.email',
        'owner.username': '$owner.username',
        'progress': '$progress',
        'profile': '$profiles',
      },
    },
  ]);

以下结果有很多我不需要在配置文件对象中使用的数据。如何在汇总查询中过滤或取消选择这些字段？例如，我只需要$ lookup profile._id字段。我不需要其余的东西。

[
    {
        "_id": "5caf5225e7179a36ac34964f",
        "owner": {
            "email": "max@*****.nl",
            "username": "Max"
        },
        "progress": [
            {
                "_id": "5caf4675999c0c14d0cda13e",
                "tool": "5c7d4c9971338741c09c6c66",
                "createdAt": "2019-04-11T13:51:49.352Z",
                "updatedAt": "2019-04-11T13:55:17.527Z",
                "file_two": true,
                "file_one": true
            }
        ],
        "profile": {
            "data": [
                25,
                25,
                25,
                25,
                25
            ],
            "tools": [
                "5c7d4c9971338741c09c6c66",
                "5c7d4c9971338741c09c6c6a",
                "5c7d4c9971338741c09c6c69",
                "5c7d4c9971338741c09c6c65",
                "5c7d4c9971338741c09c6c67"
            ],
            "_id": "5cd40f23bc30d7001730aee6",
            "answers": [
                {
                    "_id": "5cd40f23bc30d7001730aef9",
                    "subtheme": "5c7e8fe1c64c950450ada50e",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aef8",
                    "subtheme": "5c7e8fe1c64c950450ada50f",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aef7",
                    "subtheme": "5c7e8fe1c64c950450ada510",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aef6",
                    "subtheme": "5c7e8fe1c64c950450ada511",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aef5",
                    "subtheme": "5c7e8fe1c64c950450ada512",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aef4",
                    "subtheme": "5c7e8fe2c64c950450ada514",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aef3",
                    "subtheme": "5c7e8fe2c64c950450ada515",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aef2",
                    "subtheme": "5c7e8fe2c64c950450ada516",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aef1",
                    "subtheme": "5c7e8fe2c64c950450ada518",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aef0",
                    "subtheme": "5cc9ee132a945a0017498a0a",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aeef",
                    "subtheme": "5cc908e7de81ed00179a4706",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aeee",
                    "subtheme": "5c7e8fe3c64c950450ada51b",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aeed",
                    "subtheme": "5c7e8fe3c64c950450ada51d",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aeec",
                    "subtheme": "5cc9efad2a945a0017498a0b",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aeeb",
                    "subtheme": "5c7e8fe3c64c950450ada51e",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aeea",
                    "subtheme": "5c7e8fe3c64c950450ada520",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aee9",
                    "subtheme": "5c7e8fe3c64c950450ada521",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aee8",
                    "subtheme": "5c7e8fe3c64c950450ada522",
                    "answer": "disagree"
                },
                {
                    "_id": "5cd40f23bc30d7001730aee7",
                    "subtheme": "5c7e8fe4c64c950450ada523",
                    "answer": "disagree"
                }
            ],
            "profile_id": "5c864fd4f98eeb1afc9cc80e",
            "createdAt": "2019-05-09T11:29:39.733Z",
            "updatedAt": "2019-05-09T11:29:39.733Z"
        }
    }
]