CODEWITHSUNDEEP
javascriptnode.jsmongodbmongoose
Ratan Uday Kumar
Ratan Uday Kumar

Reputation: 6512

How to calculate sum of fields from mongodb collection documents using mongoose

I want to perform sum of employee points from mongodb documents.

My Documents in Employee Points Collections are like below

[
    {
        "EmployeeID": "Cust0001",
        "Point": 1,
    },
    {
        "EmployeeID": "Cust0002",
        "Point": 2,
    },
    {
        "EmployeeID": "Cust0003",
        "Point": 1,
    },
    {
        "EmployeeID": "Cust0001",
        "Point": 5,
    },
    {
        "EmployeeID": "Cust0001",
        "Point": 2,
    }
]

Expected result

[
    {
        "EmployeeID": "Cust0001",
        "Total_Points": 8
    },
    {
        "EmployeeID": "Cust0002",
        "Total_Points": 2
    },
    {
        "EmployeeID": "Cust0003",
        "Total_Points": 1
    }
]

Which is the best and most optimized way to get the output from mongodb with the total points.

I am using mongoose mongodb connection in my project.

I can manipulate data using a for loop but it seems rather inefficent.

Thanks in advance.

Comments are appreciated.

Upvotes: 3

Views: 1176

Answers (1)

Ashh
Ashh

Reputation: 46491

You need to use $sum twice here... One as "accumulator" for $group stage and one for summation of Points

db.collection.aggregate([
  { "$group": {
    "_id": "$EmployeeID",
    "Point": {
      "$sum": {
        "$sum": "$Point"
      }
    }
  }},
  { "$project": {
    "EmployeeID": "$_id",
    "Point": "$Point",
    "_id": 0
  }}
])

Ouput

[
  {
    "EmployeeID": "Cust0003",
    "Point": 1
  },
  {
    "EmployeeID": "Cust0002",
    "Point": 2
  },
  {
    "EmployeeID": "Cust0001",
    "Point": 8
  }
]

Check it here

Upvotes: 3

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