mongodbHow to aggregate in MongoDB?

MongoDB provides several ways to aggregate data from collections. The most common way is to use the aggregate() method. This method takes an array of pipeline stages as its argument and returns the aggregated result.

Example

db.collection.aggregate([
    {
        $group: {
            _id: "$department",
            totalSalary: { $sum: "$salary" }
        }
    }
])

Output example

{ "_id" : "IT", "totalSalary" : 15000 }
{ "_id" : "HR", "totalSalary" : 12000 }

Code explanation

• aggregate(): The method used to aggregate data from collections.
• $group: The operator used to group documents by a specified field and perform an aggregation on them.
• _id: The field used to specify the field to group by.
• $sum: The operator used to sum the values of a specified field.

Helpful links

• MongoDB Aggregation

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