get additional data on same collection in Mongodb C#

Question

I have a collection called "User". I'm passing userid to get the record. In addition to that i also need additional 10 last updatedAt(DateTime) record excluding the userid record but added together. So, total returned result will be 11 in this case. Is that possible using same query? I tried using Or and lookup but can't make it work as expected. Any help is appreciated.

 User collection:
[{
     "id" : "123456", 
    "name" : "foo", 
    "addressIds" : [ObjectId(234567)]
  }     ,
    "id" : "345678", 
    "name" : "bar", 
    "addressIds" : [ObjectId(678565), ObjectId(567456)]
   }]

 Address collection:
 [{
 "_id":"234567",
 "district" : "district1", 
 "pincode" : "568923",
  },
  {
 "_id":"678565",
 "district" : "district2", 
 "pincode" : "568924",
  },
  {
 "_id":"567456",
 "district" : "district3", 
 "pincode" : "568925",
 }]

Using facets, i have the User and the addressIds. Can i have the actual documents for AddressIds in User?

Answer 1

Edit: You can use $facet, like this:

db.collection.aggregate([
  {$sort: {date: -1}},
  {$facet: {
      byTate: [{$limit: 10}],
      byUser: [{$match: {userId: 455845}}]
    }
  },
  {$project: {
    byDate: {
        $filter: {
            input: "$byDate",
            as: "item",
            cond: {$ne: ["$$item",{"$arrayElemAt": ["$byUser", 0]}]}
        }
    },
    byUser: 1,
    }
  },
  {
    $project: {
      byDate: {$slice: ["$byDate", 10]},
      byUser: 1
    }
  }
])

You can see it works on the playground .

Switch between userId: 455845 / 455845 to see both cases.