MongoDb aggregation Group by Date

Question

I\'m trying to group by timestamp for the collection named \"foo\" { _id, TimeStamp }

db.foos.aggregate(
[
   {$group : { _id : new Date (Date.UTC({ $year : \'$T         


        

Answer 1

This is what I use in one of my projects :

   collection.aggregate(
      // group results by date
      {$group : {
        _id : { date : "$date" }
        // do whatever you want here, like $push, $sum...
      }},

      // _id is the date
      {$sort : { _id : -1}},                        
      {$orderby: { _id : -1 }})
    .toArray()

Where $date is a Date object in mongo. I get results indexed by date.