MongoDB sorting date string (mm/dd/yyyy)

Question

I'm storing date as string in "mm/dd/yyyy" format. I want to sort by this date field. I tried below query with few test data.

db.collection.find().sort({date: -1}).pretty()

and it is working fine. Would this work fine ever or should i convert this to MongoDate for reliable sorting?

Answer 1

Within MongoDB 3.6 you can now use $dateFromString (https://docs.mongodb.com/manual/reference/operator/aggregation/dateFromString/)

db.logmessages.aggregate( [ {
   $project: {
      date: {
         $dateFromString: {
            dateString: '$date'
         }
      }
   }
}, { $sort: { date : 1} } ] )

Answer 2

With yyyy being last, that sort isn't going to work across years.

Probably best to switch to a yyyy-mm-dd formatted string or an actual Date type. Both of those will sort correctly.