MongoDB aggregate $match stage with conditional query

I want to do a match stage in mongoDB aggregate, and in this match I want to check if a condition exists, use a custom query, and if not, use another custom query. The custom queries are nested fields.

after searching and reading documents , I write this code. But it has an error.

I use MongoDB v4.4 . only this version and cannot switch to other versions.

MongoError: FieldPath field names may not contain ‘.’.

{
  $match : {
    $expr : {
      $cond : {
        if: { $eq : [ 'type' , 'country'] },
        then: { 
          $and : [
            { 'countryState.status' : 'Confirmed' },
            { 'countryState.prop' : 'high' },          
          ]
        },
        else: {  },
      }
    }
  }
},

If the ‘type’ field, is equal to country, I want to use the custom query, and if not, only {} query.

I would appreciate anyone can help me, how to this match stage with conditional query.

>Solution :

You are asking for the query to return "this or that", so we should use $or. Borrowing the sample data from @cmgchess playground link, this query should logically do what you want I believe:

db.collection.aggregate([
  {
    $match: {
      $or: [
        {
          "type": "country",
          "countryState.status": "Confirmed",
          "countryState.prop": "high"
        },
        {
          "type": {
            $ne: "country"
          }
        }
      ]
    }
  }
])

Demo