Mongodb 2 集合与集合数组

Question

I have two collections, Collection B has a general setting, the second collections has an ID stored in the field from B in the field, it needs to join them see the result.

Collection A

{
"_id": {
    "$oid": "602ece156f898fc3a6da0440"
},
"name": "Atlas Adventures 2021",
"setup": [{
    "_id": {
        "$oid": "602ece156f898fc3a6da0441"
    },
    "typ": {
        "$oid": "602eca46ad462fc07836d5e2"
    },
    "cena": 100,
    "kapacita": 100
}, {
    "_id": {
        "$oid": "602ece156f898fc3a6da0442"
    },
    "typ": {
        "$oid": "602eca59ad462fc07836d5e3"
    },
    "cena": 50,
    "kapacita": 200
}],

}

Collection B

{
  {
      "_id": {
          "$oid": "602eca46ad462fc07836d5e2"
      },
      "nazev": "12 - 14 let - bez rozlišení\t",
      "zkratka": "A",
      "__v": 0,
      "slozeniMaximum": 2,
      "slozeniMinimum": 2,
  },
  {
      "_id": {
          "$oid": "602eca59ad462fc07836d5e3"
      },
      "zkratka": "B",
      "nazev": "15-17 let",
      "__v": 0,
      "slozeniMaximum": 2,
      "slozeniMinimum": 2,
  }
}

Need

{
  {
      "_id": {
          "$oid": "602eca46ad462fc07836d5e2"
      },
      "nazev": "12 - 14 let - bez rozlišení\t",
      "zkratka": "A",
      "slozeniMaximum": 2,
      "slozeniMinimum": 2,
      "cena": 50,
      "kapacita": 200,
  },
  {
      "_id": {
          "$oid": "602eca59ad462fc07836d5e3"
      },
      "zkratka": "B",
      "nazev": "15-17 let",
      "slozeniMaximum": 2,
      "slozeniMinimum": 2,
      "cena": 50,
      kapacita": 200,
  }
}

But I do not know how. I've tried aggregation and pipeline, but I'm doing something wrong.

Answer 1

According to this example agreggation , I created the following aggregation. There may be a problem with ObjectId.

CollectionB.aggregate([{
  $lookup: {
    from: 'CollectionA',
    let: { katId: '$_id' },
    pipeline: [
      {
        $match: {
          $expr: { $in: ['$setup.typ', '$$katId'] },
        },
      }
    ],
    as: 'kategorie',
  }
}

I still end in failure