javascript-mongodb.md

ms.custom	devx-track-js
ms.topic	include
ms.date	03/04/2021

Install mongodb SDK

To connect and use your mongoDB on Azure Cosmos DB with JavaScript and mongodb, use the following procedure.

1. Make sure Node.js and npm are installed.

2. Create a Node.js project in a new folder:

   mkdir DataDemo && \
       cd DataDemo && \
       npm init -y && \
       npm install mongodb &&
       code .

   The command:

   • Creates a project folder named DataDemo
   • Changes the Bash terminal into that folder
   • Initializes the project, which creates the package.json file
   • Installs the SDK
   • Opens the project in Visual Studio Code

Create JavaScript file to bulk insert data into MongoDB database

1. In Visual Studio Code, create a bulk_insert.js file.

2. Download the MOCK_DATA.csv file and place it in the same directory as bulk_insert.js.

3. Copy the following JavaScript code into bulk_insert.js:

   const { MongoClient } = require('mongodb');
   const ObjectId = require('mongodb').ObjectID;
   require('dotenv').config();
   
   const fs = require('fs');
   const parse = require('csv-parser')
   const { finished } = require('stream/promises');
   
   const DATABASE_URL = process.env.DATABASE_URL
       ? process.env.YOUR_RESOURCE_PRIMARY_CONNECTION_STRING
       : 'mongodb://localhost:27017';
   const DATABASE_NAME = process.env.DATABASE_NAME || 'my-tutorial-db';
   const DATABASE_COLLECTION_NAME =
       process.env.DATABASE_COLLECTION_NAME || 'my-collection';
   
   let mongoConnection = null;
   let db = null;
   let collection = null;
   
   
   // insert each row into MongoDB
   const insertData = async (readable) =>{
       
       let i = 0;
       
       for await (const row of readable) {
           console.log(`${i++} = ${JSON.stringify(row.goodreads_book_id)}`);
           await collection.insertOne(row);
       }
   }
   const bulkInsert = async () => {
       
       mongoConnection = await MongoClient.connect(DATABASE_URL, { useUnifiedTopology: true });
       db = mongoConnection.db(DATABASE_NAME);
       collection = await db.collection(DATABASE_COLLECTION_NAME);
       
       // read file, parse CSV, each row is a chunk
       const readable = fs
       .createReadStream('./books.csv')
       .pipe(parse());
   
       // Pipe rows to insert function
       await insertData(readable)
       await mongoConnection.close();
   }
   
   bulkInsert().then(() => {
       console.log('done');
   
   }).catch(err => {
       console.log(`done +  failed ${err}`)
   })
   

4. Replace the following in the script with your resource information:

   • YOUR_RESOURCE_PRIMARY_CONNECTION_STRING

5. Run the script.

   node bulk_insert.js

Create JavaScript code to use MongoDB

1. In Visual Studio Code, create a index.js file.

2. Copy the following JavaScript code into index.js:

   const { MongoClient } = require('mongodb');
   const ObjectId = require('mongodb').ObjectID;
   
   // read .env file
   require('dotenv').config();
   
   /* eslint no-return-await: 0 */
   
   const DATABASE_URL = process.env.DATABASE_URL
       ? process.env.DATABASE_URL
       : 'mongodb://localhost:27017';
   const DATABASE_NAME = process.env.DATABASE_NAME || 'my-tutorial-db';
   const DATABASE_COLLECTION_NAME =
       process.env.DATABASE_COLLECTION_NAME || 'my-collection';
   
   let mongoConnection = null;
   let db = null;
   
   /* eslint no-console: 0 */
   console.log(`DB:${DATABASE_URL}`);
   
   const insertDocuments = async (
       documents = [{ a: 1 }, { a: 2 }, { a: 3 }]
   ) => {
       // check params
       if (!db || !documents)
           throw Error('insertDocuments::missing required params');
   
       // Get the collection
       const collection = await db.collection(DATABASE_COLLECTION_NAME);
   
       // Insert some documents
       return await collection.insertMany(documents);
   };
   const findDocuments = async (
       query = { a: 3 }
   ) => {
       
       // check params
       if (!db)
           throw Error('findDocuments::missing required params');
   
       // Get the collection
       const collection = await db.collection(DATABASE_COLLECTION_NAME );
   
       // find documents
       return await collection.find(query).toArray();
   };
   
   const removeDocuments = async (
       docFilter = {}
   ) => {
       
       // check params
       if (!db )
           throw Error('removeDocuments::missing required params');
   
       // Get the documents collection
       const collection = await db.collection(DATABASE_COLLECTION_NAME);
   
       // Delete document
       return await collection.deleteMany(docFilter);
   };
   
   const connect = async (url) => {
       
       // check params
       if (!url) throw Error('connect::missing required params');
   
       return MongoClient.connect(url, { useUnifiedTopology: true });
   };
   /* 
   eslint consistent-return: [0, { "treatUndefinedAsUnspecified": false }]
   */
   const connectToDatabase = async () => {
       try {
           if (!DATABASE_URL || !DATABASE_NAME) {
               console.log('DB required params are missing');
               console.log(`DB required params DATABASE_URL = ${DATABASE_URL}`);
               console.log(`DB required params DATABASE_NAME = ${DATABASE_NAME}`);
           }
   
           mongoConnection = await connect(DATABASE_URL);
           db = mongoConnection.db(DATABASE_NAME);
   
           console.log(`DB connected = ${!!db}`);
           
           return !!db;
   
       } catch (err) {
           console.log('DB not connected - err');
           console.log(err);
       }
   };
   module.exports = {
       insertDocuments,
       findDocuments,
       removeDocuments,
       ObjectId,
       connectToDatabase
   };
   ```nodejs
   
   

3. Replace the following in the script with your resource information:

   • YOUR_RESOURCE_PRIMARY_CONNECTION_STRING

4. Run the script.

   node index.js