How to search an array of elements in a field in mongoose?

I have an array like below

arr = [123,176]

I have 2 records as

{ 
    '_id':'123',
    'geo':'-87.988'
    },
   {
   '_id':'198',
   'geo':'-98.822.
   }

I wrote the query as

arr = [123,192]

MyTable.find(_id:{$in: arr}).function(err,values){
 console.log(err);
}

Error: Cast to ObectId failed for value '123'.

Can anyone please suggest help.Thnaks.

via MMR