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Setting Up a Flask Application with SQLAlchemy

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BackendPython

Hi all,
I’m developing a web application using Flask and I want to integrate SQLAlchemy for database management. Can someone provide a step-by-step guide on setting up a Flask application with SQLAlchemy, including models and database migrations?

William Turner

9 months ago

1 Response

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Emily Parker

9 months ago

Hi,
To set up a Flask application with SQLAlchemy:

  1. Install Dependencies: Install Flask and SQLAlchemy.
pip install Flask SQLAlchemy
  1. Create Flask App: Set up the basic structure.
from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///app.db'
db = SQLAlchemy(app)

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True, nullable=False)

@app.route('/')
def hello():
    return "Hello, World!"

if __name__ == '__main__':
    app.run(debug=True)
  1. Create Database: Initialize the database.
flask shell
>>> from app import db
>>> db.create_all()
  1. Add Data: Add data to the database.
>>> from app import User
>>> user = User(username='testuser')
>>> db.session.add(user)
>>> db.session.commit()
  1. Run Migrations: Use Flask-Migrate for database migrations.
pip install Flask-Migrate

Update app.py:

from flask_migrate import Migrate
migrate = Migrate(app, db)

Initialize and run migrations:

flask db init
flask db migrate -m "Initial migration."
flask db upgrade

This setup provides a basic Flask application integrated with SQLAlchemy for database management.

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