How to sort documents from mongodb by arrays of strings

Question

For Example, I have a collection of documents called Dialogs. Format:

Dialogs{
  {
    _id: ObjectId(),
    members: [
      "admin",
      "all"
    ]
  },
  {
    _id: ObjectId(),
    members: [
      "user_637b2ed34ce3130e8532c4b9",
      "admin"
    ]
  },
  {
    _id: ObjectId(),
    members: [
      "group_637c708927f9df62ca646623",
      "admin"
    ]
  },
  {
    _id: ObjectId(),
    members: [
      "admin",
      "group_63a70e959fm566d28skkfi5b2",
      "user_427b2ed34ce4h50e8532c92h"
    ]
  },
}

I need to return sorted documents in this order: first documents containing only all, then documents containing all and some group, then just with a group, then group and users, then just users (each array has an admin string).

I tried to use aggregation, but nothing happened

Answer 1

One option is to add a field using $switch:

db.collection.aggregate([
  {$addFields: {memberTypes: {$map: {
          input: "$members",
          in: {$first: {$split: ["$$this", "_"]}}
  }}}},
  {$addFields: {
      order: {$switch: {
          branches: [
            {
              case: {$eq: [{$size: {$setUnion: ["$members", ["admin", "all"]]}}, 2]},
              then: 1
            },
            {
              case: {$in: ["all", "$members"]},
              then: 2
            },
            {
              case: {$and: [
                      {$in: ["group", "$memberTypes"]},
                      {$not: {$in: ["user", "$memberTypes"]}}
              ]},
              then: 3
            },
            {
              case: {$in: ["group", "$memberTypes"]}]},
              then: 4
            }
          ],
          default: 5
        }
      }
    }
  },
  {$sort: {order: 1}},
  {$unset: ["memberTypes", "order"]}
])

See how it works on the playground example