1. Log in to your Google Cloud Console.
2. Select or create a new project where you want your Firestore database to reside.
3. Navigate to the Firestore service in the console and set it up in either Native or Datastore Mode, depending on your requirements.
4. Go to the IAM & Admin page, then Service Accounts. Create a new service account with the necessary permissions (Firestore Data Editor) to interact with Firestore.
5. Generate a new private key for the service account and download the JSON file. This file will be used to authenticate your application with Google Cloud.

1. Connect to your MongoDB database using the MongoDB shell or a GUI tool like MongoDB Compass.
2. Use MongoDB’s export tools (mongoexport) to export the collections you want to move to Firestore. For example:

mongoexport --db=mydatabase --collection=mycollection --out=mycollection.json

1. Ensure the exported data is in a JSON format that can be easily read and written to Firestore.

1. Create a new directory for your migration script.
2. Initialize a new Node.js project by running npm init -y in your terminal.
3. Install the required npm packages:

npm install firebase-admin mongodb

4. Place your downloaded Firestore private key JSON file in the project directory.

Create a new file migrate.js in your project directory, and follow these steps:

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1. Initialize Firebase Admin SDK with your service account:

const admin = require('firebase-admin');

const serviceAccount = require('./path-to-your-service-account-file.json');

admin.initializeApp({

  credential: admin.credential.cert(serviceAccount)

});

const firestore = admin.firestore();

2. Connect to your MongoDB database:

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

const uri = "your-mongodb-connection-string";

const client = new MongoClient(uri);

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async function connectMongoDB() {

  try {

    await client.connect();

    console.log("Connected to MongoDB");

  } catch (e) {

    console.error("Connection to MongoDB failed", e);

  }

}

3. Read data from MongoDB and write it to Firestore:

async function migrateData() {

  try {

    const database = client.db("your-database-name");

    const collection = database.collection("your-collection-name");

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    const cursor = collection.find({});

    while (await cursor.hasNext()) {

      const doc = await cursor.next();

      await firestore.collection("your-firestore-collection-name").doc(doc._id.toString()).set(doc);

      console.log(`Document ${doc._id} migrated to Firestore`);

    }

  } catch (e) {

    console.error("Data migration failed", e);

  } finally {

    await client.close();

  }

}

4. Run the migration function:

async function main() {

  await connectMongoDB();

  await migrateData();

}

main().catch(console.error);

Run your script using Node.js:

node migrate.js

The script will connect to your MongoDB, read the data from the specified collection, and write each document to your Firestore collection.

After the script finishes running, verify that the data has been successfully transferred to Firestore:

1. Go to the Firestore section of the Google Cloud Console.
2. Navigate to the Data tab and browse the collections and documents to ensure your data is present and correct.

Remember to remove any sensitive data, such as the service account JSON file, from your working directory when you’re done to prevent unauthorized access.

Notes:

• This guide assumes a basic understanding of JavaScript and Node.js.
• The Firestore document IDs are set to the MongoDB document _id converted to a string. If your MongoDB _id field is not unique or if you prefer different IDs in Firestore, you’ll need to adjust the script accordingly.
• This script does not handle complex data transformations or schema migrations. If your Firestore schema differs from MongoDB, you’ll need to modify the script to transform the data as needed.
• Always test your migration script with a small subset of data before running it on your entire dataset to ensure it works as expected.