Insert, Delete, Update, Find a Document in Node.js Applications

const exp = require('express');
const app = exp();
const { MongoClient } = require('mongodb');

const dbURL = 'mongodb://127.0.0.1:27017';
const mc = new MongoClient(dbURL);

let insertOneData = {
  name: 'Dev Duo',
  age: 19,
  languages: ['C++', 'JavaScript', 'Java'],
  address: {
    city: 'Vijayawada',
    state: 'Andhra Pradesh'
  }
};

let insertManyData = [
  {
    name: 'Vignesh',
    age: 20,
    languages: ['C', 'ReactJS', 'Java'],
    address: {
      city: 'Mumbai',
      state: 'Maharashtra'
    }
  },
  {
    name: 'Pavan CH',
    age: 21,
    languages: ['C#', 'GO', 'Python'],
    address: {
      city: 'Bangalore',
      state: 'Karnataka'
    }
  }
];

let findOneData = {
  name: 'Dev Duo'
};

async function main() {
  try {
    // Connect to MongoDB
    await mc.connect();

    // Connect to Database
    const usersDatabase = mc.db('CRUD');

    // Connect to Collection
    const usersCollection = usersDatabase.collection('Users');

    // Share the Collection with the APIs
    app.set('usersCollection', usersCollection);

    console.log(`Connected to MongoDB Database: ${usersDatabase.databaseName} and Collection: ${usersCollection.collectionName} 🌍`);

    // Assign Port Number to Server
    const port = 4000;
    app.listen(port, () => {
      console.log(`Server running on port <http://localhost>:${port}`);
    });

    // Delete all Documents
    const deleteAllResult = await usersCollection.deleteMany({});
    console.log('\\nDeleted All Documents Successfully');
    console.log(deleteAllResult);

    // Insert One Document
    const insertOneResult = await usersCollection.insertOne(insertOneData);
    console.log('\\nInserted One Successfully 🚀');
    console.log(`Inserted Name: ${insertOneData.name}`);
    console.log(insertOneResult);

    // Insert Many Documents
    const insertManyResult = await usersCollection.insertMany(insertManyData);
    console.log('\\nInserted Many Successfully');
    console.log(`Inserted Names: ${insertManyData[0].name} and ${insertManyData[1].name}`);
    console.log(insertManyResult);

    // Find One Document
    const findOneResult = await usersCollection.findOne(findOneData);
    console.log('\\nFound One Document Successfully');
    console.log(findOneResult);

    // Update One Document
    const updateOneResult = await usersCollection.updateOne(
      { name: 'Dev Duo' },
      { $set: { age: 25 } }
    );
    console.log('\\nUpdated One Document Successfully');
    console.log(updateOneResult);

    // Delete One Document
    const deleteOneResult = await usersCollection.deleteOne({ name: 'Dev Duo' });
    console.log('\\nDeleted One Document Successfully');
    console.log(deleteOneResult);

  } catch (err) {
    console.error('Error in connecting to MongoDB or performing operations', err);
  }
}

main();

• Terminal Output

Creating MongoDB Transactions In Node.js Applications

Steps for the Transaction

1. Start a client session
2. Define the transaction options (Optional)
3. Define the sequence of operations to perform inside the transactions
4. Release resources used by the transaction

<aside> ⚠️ Multi-document transactions have a 60-second time limit

</aside>

1. Create variables used in the transaction.

// Collections
const accounts = client.db("bank").collection("accounts")
const transfers = client.db("bank").collection("transfers")

// Account information
let account_id_sender = "MDB574189300"
let account_id_receiver = "MDB343652528"
let transaction_amount = 100

1. Start a new session.

const session = client.startSession()

1. Begin a transaction with the WithTransaction() method on the session.

const transactionResults = await session.withTransaction(async () => {
  // Operations will go here
})

1. Update the balance field of the sender’s account by decrementing the transaction_amount from the balance field.

const senderUpdate = await accounts.updateOne(
  { account_id: account_id_sender },
  { $inc: { balance: -transaction_amount } },
  { session }
)

1. Update the balance field of the receiver’s account by incrementing the transaction_amount to the balance field.