CODEWITHSUNDEEP
mongodbmeteor
Fred J.
Fred J.

Reputation: 6019

How to sort documents in meteorhacks:aggregate output

This Meteor server code tries to group documents and sort them by the property "period" ascending but it is not doing it, any idea how to fix it? thx 

let invoicePopulation = UsageCol.aggregate([
        {
          $match: {
            action: {$in: ['a', 'b', 'c']},
            userId: doc.userId
          }
        },
        {
          $group: {
            _id: {period: "$period"},
            count: {$sum: 1}
          }
        },
        {
          "$sort" : {
            "period" : 1
          }
        }
      ]);

      //output
      [{"_id":{"period":"42017"},"count":14},{"_id":{"period":"22017"},"count":1},{"_id":{"period":"32017"},"count":271}]

//needs to be 
[{"_id":{"period":"22017"},"count":1},{"_id":{"period":"32017"},"count":271},{"_id":{"period":"42017"},"count":14}]

Upvotes: 0

Views: 70

Answers (1)

jordanwillis
jordanwillis

Reputation: 10705

Your $group looks strange to me. Typically you want to group on a specific field and that field would become your _id (since the field is now unique).

The way you have it in your code is setting a sub document as the value for _id. If that is truly what you want, then your $sort should be this.

{
  $sort: {
    "_id.period": 1
  }
}

If you are not trying to create an _id sub-document, then you should fix your $group like this.

let invoicePopulation = UsageCol.aggregate([
  {
    $match: {
      action: {$in: ['a', 'b', 'c']},
      userId: doc.userId
    }
  },
  {
    $group: {
      _id: "$period",
      count: {$sum: 1}
    }
  },
  {
    $sort : {
      "period" : 1
    }
  }
]);

Upvotes: 1

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