CODEWITHSUNDEEP
mongodbmongoose
DD DD
DD DD

Reputation: 1228

How to use sum with Mongodb aggregate

I have a date as below in mongoDB.

[
  {
  condition: {
    test: [
           { ...},
           { ...},
           { ...}
           ]
  }
  },
  {
  condition: {
    test: [
           { ...},
           { ...}
           ]
  }
  },
  ...
]

And I want to get a sum value of test. For example, ('the number of test' - 1) and sum them.
In this case, (3 - 1) + (2 - 1) = 3. How can I make this sum value at one time using one aggregate of Mongodb?
Thank you so much for reading it.

Upvotes: 0

Views: 66

Answers (1)

Mohit Hurkat
Mohit Hurkat

Reputation: 416

db.collectionName.aggregate([
  {
    $group:
      { _id: null,
        totalSize:
          { $sum:
              { $add:
                  [{ $size: "$test"},-1]
              }
          }
      }
  }
])

Tested over the below data

/* 1 */
{
    "_id" : ObjectId("5e31333fab4013230264d786"),
    "condition" : "testCase1",
    "test" : [ 
        ISODate("2020-01-29T07:26:42.491Z"), 
        ISODate("2020-01-29T07:27:42.491Z")
    ]
}

/* 2 */
{
    "_id" : ObjectId("5e313346ab4013230264d787"),
    "condition" : "testCase2",
    "test" : [ 
        ISODate("2020-01-29T07:25:42.491Z"), 
        ISODate("2020-01-29T07:24:42.491Z"), 
        ISODate("2020-01-29T07:23:42.491Z")
   ]
}

Output :

{
  "_id" : null,
  "totalSize" : 3.0
}

Upvotes: 1

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