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Manthan Ankolekar
Manthan Ankolekar

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Building a CRUD Application with Flask and MongoDB

#python #webdev #programming #beginners

In this blog, we will build a simple CRUD (Create, Read, Update, Delete) API using Flask and MongoDB. Unlike traditional relational databases, MongoDB is a NoSQL database that stores data in flexible, JSON-like documents. We will use Flask-PyMongo for database interactions.

Prerequisites

Ensure you have the following installed:

  • Python 3.x
  • MongoDB
  • Flask
  • Flask-PyMongo
  • Flask-CORS

Project Setup

1. Clone the Repository 

git clone https://github.com/manthanank/crud-flask-mongodb.git cd crud-flask-mongodb
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2. Create a Virtual Environment 

python -m venv venv source venv/bin/activate # On Windows: `venv\Scripts\activate`
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3. Install Dependencies 

pip install -r requirements.txt
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4. Configure the Environment

Copy the .env.example file to .env and update the MongoDB URI if necessary:

cp .env.example .env
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Inside .env, set the MongoDB connection string:

MONGO_URI=mongodb://localhost:27017/flaskdb
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5. Run the Application 

python run.py
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The API will be available at http://127.0.0.1:5000/api/items.

Project Structure 

crud-flask-mongodb/ │── app/ │ ├── __init__.py │ ├── config.py │ ├── database.py │ ├── models.py │ ├── routes.py │── .env.example │── requirements.txt │── run.py │── README.md │── LICENSE
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Configuring the Flask Application

We define the Flask configuration in app/config.py:

import os from dotenv import load_dotenv load_dotenv() class Config: MONGO_URI = os.getenv("MONGO_URI", "mongodb://localhost:27017/flaskdb")
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We initialize Flask and MongoDB in app/__init__.py:

from flask import Flask from flask_cors import CORS from app.config import Config from app.database import mongo def create_app(): app = Flask(__name__) app.config.from_object(Config) mongo.init_app(app) CORS(app) from app.routes import api_bp app.register_blueprint(api_bp, url_prefix="/api") return app
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Defining the Model

Since MongoDB is a NoSQL database, we use dictionaries instead of SQLAlchemy models. We define a helper function in app/models.py to format MongoDB documents:

from app.database import mongo class Item: @staticmethod def to_dict(item): return { "id": str(item["_id"]), "name": item["name"], "description": item.get("description", ""), }
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Creating API Routes

We define CRUD routes in app/routes.py using Flask Blueprints.

1. Create an Item 

@api_bp.route("/items", methods=["POST"]) def create_item(): data = request.json item = {"name": data["name"], "description": data.get("description")} result = mongo.db.items.insert_one(item) return jsonify({"id": str(result.inserted_id), **item}), 201
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2. Retrieve All Items 

@api_bp.route("/items", methods=["GET"]) def get_items(): items = mongo.db.items.find() return jsonify([Item.to_dict(item) for item in items])
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3. Retrieve a Single Item 

@api_bp.route("/items/<string:item_id>", methods=["GET"]) def get_item(item_id): item = mongo.db.items.find_one({"_id": ObjectId(item_id)}) if item: return jsonify(Item.to_dict(item)) return jsonify({"error": "Item not found"}), 404
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4. Update an Item 

@api_bp.route("/items/<string:item_id>", methods=["PUT"]) def update_item(item_id): data = request.json update_data = {"$set": {"name": data.get("name"), "description": data.get("description")}} result = mongo.db.items.update_one({"_id": ObjectId(item_id)}, update_data) if result.matched_count: updated_item = mongo.db.items.find_one({"_id": ObjectId(item_id)}) return jsonify(Item.to_dict(updated_item)) return jsonify({"error": "Item not found"}), 404
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5. Delete an Item 

@api_bp.route("/items/<string:item_id>", methods=["DELETE"]) def delete_item(item_id): result = mongo.db.items.delete_one({"_id": ObjectId(item_id)}) if result.deleted_count: return jsonify({"message": "Item deleted successfully"}) return jsonify({"error": "Item not found"}), 404
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Testing the API

You can test the API using Postman or cURL.

  • Create an Item: 
 curl -X POST http://127.0.0.1:5000/api/items -H "Content-Type: application/json" -d '{"name": "Laptop", "description": "Gaming laptop"}'
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  • Get All Items: 
 curl -X GET http://127.0.0.1:5000/api/items
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  • Get a Specific Item: 
 curl -X GET http://127.0.0.1:5000/api/items/1
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  • Update an Item: 
 curl -X PUT http://127.0.0.1:5000/api/items/1 -H "Content-Type: application/json" -d '{"name": "Updated Laptop", "description": "High-performance gaming laptop"}'
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  • Delete an Item: 
 curl -X DELETE http://127.0.0.1:5000/api/items/1
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Conclusion

In this guide, we built a Flask CRUD API with MongoDB, using Flask-PyMongo for database interactions. This setup provides a solid foundation for building RESTful services in Flask with NoSQL databases.

🎉 Congratulations! You’ve built a Flask CRUD API with MongoDB. 🚀

Happy coding! 🚀

Exploring the Code

Visit the GitHub repository to explore the code in detail.

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