$eq

The $eq aggregation operator compares two values and returns true if they are equal, otherwise returns false.

Parameters

• expression1: The first value to compare.

• expression2: The second value to compare.

Example (MongoDB Shell)

The following example demonstrates using the $eq operator to check if product quantities match target values.

Create sample documents

db.inventory.insertMany([
  { _id: 1, item: "Widget", qty: 50, target: 50 },
  { _id: 2, item: "Gadget", qty: 30, target: 50 },
  { _id: 3, item: "Tool", qty: 50, target: 40 }
]);

Query example

db.inventory.aggregate([
  {
    $project: {
      item: 1,
      qty: 1,
      target: 1,
      meetsTarget: { $eq: ["$qty", "$target"] }
    }
  }
]);

Output

[
  { _id: 1, item: 'Widget', qty: 50, target: 50, meetsTarget: true },
  { _id: 2, item: 'Gadget', qty: 30, target: 50, meetsTarget: false },
  { _id: 3, item: 'Tool', qty: 50, target: 40, meetsTarget: false }
]

Code examples

To view a code example for using the $eq aggregation operator, 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('inventory');

  const result = await collection.aggregate([
    {
      $project: {
        item: 1,
        qty: 1,
        target: 1,
        meetsTarget: { $eq: ["$qty", "$target"] }
      }
    }
  ]).toArray();

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

example();

Python

from pymongo import MongoClient

def example():
    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['inventory']

    result = list(collection.aggregate([
        {
            '$project': {
                'item': 1,
                'qty': 1,
                'target': 1,
                'meetsTarget': { '$eq': ['$qty', '$target'] }
            }
        }
    ]))

    print(result)
    client.close()

example()