how to match both fields are not exist

Question

1. I was trying to use $and to express both fields are empty
2. Here is the code

    db.tweets_v2.aggregate({
      {match:{$and:[{replyto_id:$exist:false},{replyto_id:$exist:false}]}
    });

Answer 1

There are few fixes,

• $exist should be $exists
• missed {} brackets before and after in $exists
• match should be $match
• aggregation stages start from [] not {}

db.tweets_v2.aggregate([
  {
    $match: {
      $and: [
        { replyto_id: { $exists: false } },
        { replyfrom_id: { $exists: false } } // change your second field name
      ]
    }
  }
])

Playground

Answer 2

Actually the $and is not needed, this one will also work:

db.tweets_v2.aggregate([
  {
    $match: {
        replyto_id: { $exists: false } ,
        replyfrom_id: { $exists: false }
    }
  }
])