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$sort (aggregation)

The $sort stage in the aggregation pipeline is used to order the documents in the pipeline by a specified field or fields. This stage helps you sort data, like arranging sales by amount or events by date.

Syntax

The syntax for the $sort stage is as follows:

{
  $sort: { <field1>: <sort order>, <field2>: <sort order>, ... }
}

Parameters

Description
field The field to sort by
sort order The order in which we should sort the field. 1 for ascending order and -1 for descending order.

Examples

Example 1: Sorting by Total Sales in Descending Order

To sort the sales categories by their total sales in descending order:

db.collection.aggregate([
  {
    $unwind: "$store.sales.salesByCategory"
  },
  {
    $sort: { "store.sales.salesByCategory.totalSales": -1 }
  }
])

Sample output

[
  {
    "_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5",
    "store": {
      "name": "Downtown Store",
      "sales": {
        "salesByCategory": [
          {
            "category": "Electronics",
            "totalSales": 15000
          },
          {
            "category": "Clothing",
            "totalSales": 12000
          },
          {
            "category": "Home Goods",
            "totalSales": 10000
          }
        ]
      }
    }
  },
  {
    "_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c6",
    "store": {
      "name": "Uptown Store",
      "sales": {
        "salesByCategory": [
          {
            "category": "Electronics",
            "totalSales": 20000
          },
          {
            "category": "Clothing",
            "totalSales": 18000
          },
          {
            "category": "Home Goods",
            "totalSales": 15000
          }
        ]
      }
    }
  }
]

Example 2: Sorting by Event Start Date in Ascending Order

To sort the promotion events by their start dates in ascending order:

db.collection.aggregate([
  {
    $unwind: "$store.promotionEvents"
  },
  {
    $sort: { "store.promotionEvents.promotionalDates.startDate": 1 }
  }
])

Sample output

[
  {
    "_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5",
    "store": {
      "name": "Downtown Store",
      "promotionEvents": [
        {
          "eventName": "Summer Sale",
          "promotionalDates": {
            "startDate": ISODate("2024-06-01T00:00:00Z"),
            "endDate": ISODate("2024-06-30T23:59:59Z")
          }
        },
        {
          "eventName": "Black Friday",
          "promotionalDates": {
            "startDate": ISODate("2024-11-25T00:00:00Z"),
            "endDate": ISODate("2024-11-25T23:59:59Z")
          }
        },
        {
          "eventName": "Holiday Deals",
          "promotionalDates": {
            "startDate": ISODate("2024-12-01T00:00:00Z"),
            "endDate": ISODate("2024-12-31T23:59:59Z")
          }
        }
      ]
    }
  },
  {
    "_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c6",
    "store": {
      "name": "Uptown Store",
      "promotionEvents": [
        {
          "eventName": "Back to School",
          "promotionalDates": {
            "startDate": ISODate("2024-08-01T00:00:00Z"),
            "endDate": ISODate("2024-08-31T23:59:59Z")
          }
        },
        {
          "eventName": "Winter Sale",
          "promotionalDates": {
            "startDate": ISODate("2024-12-01T00:00:00Z"),
            "endDate": ISODate("2024-12-31T23:59:59Z")
          }
        }
      ]
    }
  }
]

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