Jassif Team Institution

let MongoClient = require('mongodb').MongoClient;
let url = "mongodb://localhost:27017/mydb";

MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  console.log("Database created!");
  db.close();
});

C:\Users\Your Name>node demo_create_mongo_db.js

Database created!

const { MongoClient } = require('mongodb');

async function createDatabase() {
  const uri = "mongodb://localhost:27017/mydb";
  const client = new MongoClient(uri);

  try {
    await client.connect();
    console.log("Connected successfully to server");
    console.log("Database 'mydb' is ready to use!");
  } catch (err) {
    console.error("Error:", err);
  } finally {
    await client.close();
  }
}

createDatabase();

const { MongoClient } = require('mongodb');

async function connectToCloud() {
  // Replace with your MongoDB Atlas connection string
  const uri = "mongodb+srv://username:password@cluster0.mongodb.net/mydb?retryWrites=true&w=majority";
  const client = new MongoClient(uri);

  try {
    await client.connect();
    console.log("Connected to MongoDB Atlas");
    console.log("Database created or connected successfully");
  } catch (err) {
    console.error("Connection error:", err);
  } finally {
    await client.close();
  }
}

connectToCloud();

const { MongoClient } = require('mongodb');

async function createDatabaseWithContent() {
  const uri = "mongodb://localhost:27017/mydb";
  const client = new MongoClient(uri);

  try {
    await client.connect();
    const database = client.db("mydb");
    const collection = database.collection("users");
    
    // Insert first document - this actually creates the database
    const result = await collection.insertOne({
      name: "John Doe",
      email: "john@example.com",
      createdAt: new Date()
    });
    
    console.log("Database and collection created!");
    console.log("First document inserted with id:", result.insertedId);
    
  } catch (err) {
    console.error("Error:", err);
  } finally {
    await client.close();
  }
}

createDatabaseWithContent();

const { MongoClient } = require('mongodb');

async function listDatabases() {
  const uri = "mongodb://localhost:27017";
  const client = new MongoClient(uri);

  try {
    await client.connect();
    const databaseList = await client.db().admin().listDatabases();
    
    console.log("Databases:");
    databaseList.databases.forEach(db => {
      console.log(` - ${db.name}`);
    });
    
  } catch (err) {
    console.error("Error:", err);
  } finally {
    await client.close();
  }
}

listDatabases();

const { MongoClient } = require('mongodb');

async function checkDatabaseExists() {
  const uri = "mongodb://localhost:27017";
  const client = new MongoClient(uri);
  const dbName = "mydb";

  try {
    await client.connect();
    const databaseList = await client.db().admin().listDatabases();
    const exists = databaseList.databases.some(db => db.name === dbName);
    
    if (exists) {
      console.log(`Database '${dbName}' exists`);
    } else {
      console.log(`Database '${dbName}' does not exist`);
    }
    
  } catch (err) {
    console.error("Error:", err);
  } finally {
    await client.close();
  }
}

checkDatabaseExists();

const { MongoClient } = require('mongodb');

class DatabaseManager {
  constructor(connectionString) {
    this.connectionString = connectionString;
    this.client = new MongoClient(connectionString);
  }

  async connect() {
    try {
      await this.client.connect();
      console.log("Connected to MongoDB server");
      return true;
    } catch (error) {
      console.error("Connection failed:", error);
      return false;
    }
  }

  async createDatabase(dbName) {
    try {
      const db = this.client.db(dbName);
      // Test the connection by listing collections
      const collections = await db.listCollections().toArray();
      console.log(`Database '${dbName}' is accessible`);
      console.log(`Existing collections: ${collections.length}`);
      return db;
    } catch (error) {
      console.error("Error accessing database:", error);
      throw error;
    }
  }

  async ensureDatabaseAndCollection(dbName, collectionName) {
    try {
      const db = this.client.db(dbName);
      const collection = db.collection(collectionName);
      
      // Insert a temporary document to ensure creation
      const tempDoc = {
        _id: "temp_creation_doc",
        createdAt: new Date(),
        purpose: "Database and collection creation"
      };
      
      await collection.insertOne(tempDoc);
      await collection.deleteOne({ _id: "temp_creation_doc" });
      
      console.log(`Database '${dbName}' and collection '${collectionName}' are ready`);
      return { db, collection };
    } catch (error) {
      console.error("Error ensuring database and collection:", error);
      throw error;
    }
  }

  async close() {
    try {
      await this.client.close();
      console.log("Connection closed");
    } catch (error) {
      console.error("Error closing connection:", error);
    }
  }
}

// Usage example
async function main() {
  const connectionString = "mongodb://localhost:27017";
  const dbManager = new DatabaseManager(connectionString);

  try {
    const connected = await dbManager.connect();
    if (!connected) return;

    // Create/access database
    const db = await dbManager.createDatabase("myapp");
    
    // Ensure database and collection exist
    const { collection } = await dbManager.ensureDatabaseAndCollection("myapp", "users");
    
    console.log("Database setup completed successfully!");
    
  } catch (error) {
    console.error("Main function error:", error);
  } finally {
    await dbManager.close();
  }
}

// Run the example
main();