Mongo groupby month using UNIX millisecond time

Question

I have a Mongo collection that looks as follows:

[{
    id: 1,
    timestamp: 1534488870841,
    type: \'deposit\'
}, {
    id: 1,
    timestamp: 15344889151         


        

Answer 1

You can try below aggregation in mongodb 4.0

You can convert timestamp to date using $toDate aggregation and then $group with $month aggregation

db.collection.aggregate([
  { "$match": { "type": "deposits" }},
  { "$addFields": {
    "date": {
      "$toDate": "$timestamp"
    }
  }},
  { "$group": {
    "_id": { "$month": "$date" },
    "deposits": {
      "$push": "$$ROOT"
    }
  }}
])

You can try below aggregation in mongodb 3.4

In 3.4 you can convert timestamp to date by adding new Date() in it and $group it by using $dateToString aggregation

db.collection.aggregate([
  { "$match": { "type": "deposits" }},
  { "$addFields": {
    "date": {
      "$add": [ new Date(0), "$timestamp" ]
    }
  }},
  { "$group": {
    "_id": {
      "$dateToString": {
        "format": "%m",
        "date": "$date"
      }
    },
    "deposits": {
      "$push": "$$ROOT"
    }
  }}
])