How to Use SQLAlchemy with Flask for Database Management
🗃️ How to Use SQLAlchemy with Flask for Database Management
SQLAlchemy is a powerful Python ORM (Object Relational Mapper) that integrates seamlessly with Flask. It allows you to interact with your database using Python classes instead of raw SQL.
🔧 1. Install Flask and SQLAlchemy
You can install both using pip:
bash
Copy
Edit
pip install Flask SQLAlchemy
If you're planning to use a virtual environment (recommended):
bash
Copy
Edit
python -m venv venv
source venv/bin/activate # On Windows: venv\Scripts\activate
pip install Flask SQLAlchemy
📁 2. Basic Project Structure
arduino
Copy
Edit
/flask_app
├── app.py
├── models.py
├── config.py
└── requirements.txt
⚙️ 3. Configuration Setup
config.py
python
Copy
Edit
import os
BASE_DIR = os.path.abspath(os.path.dirname(__file__))
class Config:
SQLALCHEMY_DATABASE_URI = 'sqlite:///' + os.path.join(BASE_DIR, 'app.db')
SQLALCHEMY_TRACK_MODIFICATIONS = False
🚀 4. Initialize Flask and SQLAlchemy
app.py
python
Copy
Edit
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from config import Config
app = Flask(__name__)
app.config.from_object(Config)
db = SQLAlchemy(app)
# Import models after db is initialized
from models import User
@app.route('/')
def index():
return "Hello, Flask with SQLAlchemy!"
if __name__ == '__main__':
app.run(debug=True)
🧱 5. Define Your Database Models
models.py
python
Copy
Edit
from app import db
class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(80), unique=True, nullable=False)
email = db.Column(db.String(120), unique=True, nullable=False)
def __repr__(self):
return f'<User {self.username}>'
🛠️ 6. Create the Database and Tables
Run Python in the shell or create a script:
bash
Copy
Edit
python
python
Copy
Edit
from app import db
db.create_all()
exit()
This will create a file called app.db with the tables defined in your models.
✍️ 7. Add and Query Data
Example shell usage:
python
Copy
Edit
from app import db
from models import User
# Create a user
new_user = User(username="john", email="john@example.com")
db.session.add(new_user)
db.session.commit()
# Query users
users = User.query.all()
print(users)
# Filter
john = User.query.filter_by(username="john").first()
print(john.email)
✅ 8. Best Practices
Use Flask-Migrate for migrations (pip install flask-migrate)
Structure your app using Blueprints for larger projects
Set environment variables for DB credentials in production
📦 9. Using Flask-Migrate (Optional but Recommended)
To manage database schema changes easily:
bash
Copy
Edit
pip install Flask-Migrate
In app.py:
python
Copy
Edit
from flask_migrate import Migrate
migrate = Migrate(app, db)
Then run:
bash
Copy
Edit
flask db init
flask db migrate -m "Initial migration"
flask db upgrade
🎯 Conclusion
With Flask and SQLAlchemy, you can:
✅ Define models with Python classes
✅ Interact with databases using ORM
✅ Manage migrations with Flask-Migrate
✅ Build full-featured apps with clean database integration
Learn Full Stack Python Course in Hyderabad
Read More
Introduction to MongoDB for Full Stack Python
Creating and Managing Relationships in Databases with Django ORM
Implementing Authentication with Databases in Python
Using Django ORM to Interact with Databases
Visit Our Quality Thought Training in Hyderabad
Comments
Post a Comment