Mongodb 在localfield中具有键的多个集合上聚合

我有三个相互关联的收藏

Partner
   {
        "_id": "5d68b91f0ef87f0c36ad1f7b",
        "name": "1111 Vijay Dev",
   }

 Event {
    "oneTime": true,
    "_id": "5d6cfc09967a6f45c51d4375",
    "title": "WelcomeOneEvent1",
   }

User which contains data for both Partner and Event with Keys partnerId and eventId
    {
    "_id": ObjectId("5d68f06e3058326af09d6c53"),
    "firstName": "Demo",
    "partners": [
    {
    "_id": ObjectId("5d6cafd3e109107b83068657"),
    "partnerId": ObjectId("5d4d60d6f45f1c6e723bc074") 
    } 
    ],
    "events": [
    {
    "_id": ObjectId("5d6cfc18967a6f45c51d437b"),
    "eventId": ObjectId("5d6a4b882d267958eb82071c") 
    },
    {
    "_id": ObjectId("5d6cfc18967a6f45c51d437a"),
    "eventId": ObjectId("5d6cfc09967a6f45c51d4375") 
    } 
    ] 
    }

我需要获得所有合作伙伴的列表，以及这些用户的事件

我尝试与用户一起获取partners数组，结果成功，但无法获取事件详细信息。下面是我的代码

partnerSchema.statics.chking = function() {
  return new Promise((resolve, reject) => {
    this.aggregate(
      [
    {
      $lookup: {
        from: 'users',
        localField: '_id',
        foreignField: 'partners.partnerId',
        as: 'users'
      }
    },
    {
      $unwind:{
          'path': '$user.events',
          'preserveNullAndEmptyArrays': true
        }
    },
    {
      $lookup: {
        from: 'events',
        localField: 'users.events.eventId',
        foreignField: '_id',
        as: 'events'
      }
    },
    {
      $project: {
        name: 1,
        'users._id': 1,
        'users.firstName': 1,
        'users.events': '$events'
      }
    }
  ],
  function(err, result) {
    console.log('result', result)
    if (err) return reject(err)
    resolve(result)
  }
)
})
}

实际结果是这样的。我需要添加缺少的事件详细信息，如id和标题：

{
"data": [
   {
        "_id": "5d68b91f0ef87f0c36ad1f7b",
        "name": "1111 Vijay Dev",
        "users": [
            {
                "_id": "5d6a144f498ea95bf51298ea",
                "firstName": "Vijay one",
                "events": []
            },
            {
                "_id": "5d6a1459498ea95bf51298ec",
                "firstName": "vijay 2",
                "events": []
            },
            {
                "_id": "5d6d046c0b6700548397e262",
                "firstName": "check11",
                "events": []
            }
        ]
    }
]
}

预期：

{
"data": [
   {
        "_id": "5d68b91f0ef87f0c36ad1f7b",
        "name": "1111 Vijay Dev",
        "users": [
            {
                "_id": "5d6a144f498ea95bf51298ea",
                "firstName": "Vijay one",
                "events": [
                          { "_id": "5d6cfc09967a6f45c51d4374",
                            "title": "WelcomeOneEvent1"},
                          { "_id": "5d6cfc09967a6f45c51d4375",
                            "title": "WelcomeTwoEvent2"},
                          ]
            },
            {
                "_id": "5d6a1459498ea95bf51298ec",
                "firstName": "vijay 2",
                "events": []
            },
            {
                "_id": "5d6d046c0b6700548397e262",
                "firstName": "check11",
                "events": []
            }
        ]
    }
]
}

请试试这个：

Partner.aggregate([
    {
        $lookup: {
            from: 'users',
            localField: '_id',
            foreignField: 'partners.partnerId',
            as: 'users'
        }
    },
    {
        $unwind: {
            'path': '$users',
            'preserveNullAndEmptyArrays': true
        }
    },
    {
        $lookup: {
            from: 'events',
            localField: 'users.events.eventId',
            foreignField: '_id',
            as: 'events'
        }
    }, { $addFields: { 'users.events': '$events' } }, { $group: { _id: '$_id', users: { $push: '$users' }, data: { $first: '$$ROOT' } } }, { $addFields: { 'data.users': '$users' } },
    { $replaceRoot: { 'newRoot': '$data' } }, {
        $project: {
            name: 1,
            'users._id': 1,
            'users.firstName': 1,
            'users.events': 1
        }
    }

])

---

谢谢，但这不起作用，事件仍然是空数组。@user5337216:您的_id是否在partner中，而事件是实际的objectid或字符串？我已经测试了它，并且它按预期工作，在您制作“PreserveNullandEmptyArray”和投影事件时，如果合作伙伴没有用户，您仍然会看到空事件，但对于正确的数据，您应该看到事件