Connecting MongoDB with a Python Flask Application

Prerequisites

Before starting, ensure you have the following:

• Flask installed in your Python environment.
• MongoDB installed locally or a running MongoDB server.
• Python 3 installed with pip.
• Basic knowledge of Flask and Python.

Step 1: Install Required Python Packages

Install the necessary Python packages to connect Flask to MongoDB:

pip install Flask pymongo dnspython

pymongo is the official MongoDB driver for Python, and dnspython helps with DNS resolution for MongoDB URIs.

Step 2: Set Up a MongoDB Database

1. Start MongoDB: Ensure your MongoDB server is running. If you installed MongoDB locally, use the following command to start it:

   mongod

2. Create a Database: Use MongoDB Compass or the CLI to create a new database, for example, mydatabase.

3. Create a Collection: Inside mydatabase, create a collection, for example, users.

Step 3: Configure Flask Application

Create a file named app.py and include the following code to connect your Flask application to MongoDB:

from flask import Flask, jsonify, request
from pymongo import MongoClient

app = Flask(__name__)

# Replace with your MongoDB URI
MONGO_URI = "mongodb://127.0.0.1:27017"
client = MongoClient(MONGO_URI)

db = client['mydatabase']
users_collection = db['users']

@app.route('/add_user', methods=['POST'])
def add_user():
    user_data = request.json
    result = users_collection.insert_one(user_data)
    return jsonify({"message": "User added", "user_id": str(result.inserted_id)})

@app.route('/get_user/<name>', methods=['GET'])
def get_user(name):
    user = users_collection.find_one({"name": name})
    if user:
        user["_id"] = str(user["_id"])
        return jsonify(user)
    return jsonify({"error": "User not found"}), 404

if __name__ == '__main__':
    app.run(debug=True)

Step 4: Run the Application

Run your Flask application using the following command:

python app.py

Testing Endpoints

1. Add a User: Use a tool like Postman or curl to test the /add_user endpoint:

   curl -X POST -H "Content-Type: application/json" \
   -d '{"name": "John Doe", "email": "[email protected]"}' \
   http://127.0.0.1:5000/add_user

2. Get a User: Test the /get_user/<name> endpoint:

   curl http://127.0.0.1:5000/get_user/John%20Doe

Step 5: Use Environment Variables for Configuration

Avoid hardcoding sensitive information. Use environment variables for the MongoDB URI.

Using python-dotenv

Install python-dotenv:

pip install python-dotenv

Create a .env file:

MONGO_URI=mongodb://127.0.0.1:27017

Update app.py:

from dotenv import load_dotenv
import os

load_dotenv()

MONGO_URI = os.getenv("MONGO_URI")
client = MongoClient(MONGO_URI)

Step 6: Advanced Usage

• Indexes: Create indexes in your collections to improve query performance.
• Authentication: Use a MongoDB URI with username and password for authenticated databases.
• Connection Pooling: Configure connection pooling in MongoClient for better performance.

Conclusion

By following these steps, you can connect a MongoDB database to your Flask application. This setup is compatible with a variety of Flask extensions and forms the foundation for building scalable web applications.