$add - Amazon DocumentDB
Example (MongoDB Shell)Code examples
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$add

The $add operator in Amazon DocumentDB is used to add numbers or dates together. It can be used to perform arithmetic operations on numeric fields or to perform date arithmetic by adding a number of time units to a date field.

Parameters

  • expression1: The first number or date to add.

  • expression2: The second number or date to add.

  • expression3: (optional) Additional numbers or dates to add.

Example (MongoDB Shell)

The following example demonstrates how to use the $add operator to add two numbers together.

Create sample documents

db.numbers.insertMany([
  { _id: 1, a: 5, b: 3 },
  { _id: 2, a: 10, b: 7 },
  { _id: 3, a: 2, b: 8 }
]);

Query example

db.numbers.aggregate([
  { $project: {
    _id: 1,
    sum: { $add: ["$a", "$b"] }
  }}
])

Output

[
  { "_id" : 1, "sum" : 8 },
  { "_id" : 2, "sum" : 17 },
  { "_id" : 3, "sum" : 10 }
]

In this example, the $add operator is used to add the values of the a and b fields for each document and store the result in the sum field.

Code examples

To view a code example for using the $add command, choose the tab for the language that you want to use:

Node.js
const { MongoClient } = require('mongodb');

async function example() {
  const client = await MongoClient.connect('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false');
  const db = client.db('test');
  const collection = db.collection('numbers');

  const result = await collection.aggregate([
    { $project: {
      _id: 1,
      sum: { $add: ['$a', '$b'] }
    }}
  ]).toArray();

  console.log(result);
  client.close();
}

example();
Python
from pymongo import MongoClient

client = MongoClient('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false')
db = client['test']
collection = db['numbers']

result = list(collection.aggregate([
    { '$project': {
        '_id': 1,
        'sum': { '$add': ['$a', '$b'] }
    }}
]))

print(result)
client.close()