How to Connect Flask App to MongoDB Database

Video Tutorial

Prerequisites

Before starting, ensure you have the following:

Python installed on your machine (preferably version 3.6 or later)
A MongoDB instance (You can use a local MongoDB installation or a cloud provider like MongoDB Atlas)

Step 1: Install Dependencies

Install Flask-PyMongo to connect Flask with MongoDB:

pip install Flask-PyMongo

Step 2: Configure Flask-Pymongo

Create app.py with the following code:

from flask import Flask
from flask_pymongo import PyMongo

# Creating a Flask app instance
app = Flask(__name__)

# Configure MongoDB Connection URI
# NOTE: Change URI for MongoDB Atlas
app.config["MONGO_URI"] = "mongodb://localhost:27017/test"

# Creating a PyMongo Instance
mongo = PyMongo(app)

if __name__ == "__main__":
    # Run the app in debug mode
    app.run(debug=True)

Step 3: Test the MongoDB Connection

Now, test the connection by adding a few routes. The first will confirm the connection, and the second will allow you to add and retrieve users.

from flask import request, jsonify

# Test connection
@app.route("/")
def home():
    return "Connected to MongoDB!"

# Add a user
@app.route("/users", methods=["POST"])
def add_user():
    users = mongo.db.users
    users.insert_one({
		    'username': request.json["username"], 
				'email': request.json["email"]
		})
    return jsonify({"message": "User added!"}), 201

# Get users
@app.route("/users", methods=["GET"])
def get_users():
    users = mongo.db.users.find()
    return jsonify(
		    [{
				    "username": user["username"], 
						"email": user["email"]
				} for user in users]
		)

Step 4: Run the App

Start your Flask app:

python app.py

Visit http://127.0.0.1:5000 to see it in action!

Conclusion

That’s it! You've successfully connected Flask to MongoDB. You can now perform basic operations like adding and retrieving users.

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