CODEWITHSUNDEEP
mongodbmongodb-query
Suraj Dalvi
Suraj Dalvi

Reputation: 1078

MongoQuery to update document using addition

I have the following document in student collection:

{
"uid": 1,
"eng": 70
}

Now I want to add 10 into eng field and want result 80. to do this I am using following query:

db.getCollection('student').aggregate([{$match:{uid:1}},{$set:{eng:{$sum:10}}}])

but it is not working. SO how can add any number in the field to the required output? is any addition query in MongoDB. help me here

Upvotes: 1

Views: 325

Answers (2)

Dheemanth Bhat
Dheemanth Bhat

Reputation: 4452

SOLUTION #1: Set sum to the same field eng.

db.student.aggregate([
    { $match: { uid: 1 } },
    {
        $set: {
            eng: { $add: ["$eng", 10] }        // $sum: ["$eng", 10] Also works;)
        }
    }
])

Output:

{
    "_id" : ObjectId("6065f94abb72032a689ed61d"),
    "uid" : 1,
    "eng" : 80
}

SOLUTION #2: Set sum to a different field result.

  1. Using $addFields add result filed.
  2. Using $add add 10 to eng and store it in result.
db.student.aggregate([
    { $match: { uid: 1 } }, 
    { 
        $addFields: { 
            result: { $add: ["$eng", 10] }    
        } 
    }
])

Output:

{
    "_id" : ObjectId("6065f94abb72032a689ed61d"),
    "uid" : 1,
    "eng" : 70,
    "result" : 80
}

Upvotes: 1

Tim Biegeleisen
Tim Biegeleisen

Reputation: 521249

I suggest using the $inc operator here:

db.getCollection('student').update(
    { uid: 1 },
    { $inc: { eng: 10 } }
)

Upvotes: 1

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