setup

name	setup
description	Use when the user asks to "verify SQLAlchemy setup", "check database connection", "is SQLAlchemy configured correctly", "test database setup", or needs to confirm that SQLAlchemy is properly initialized in their Python project.

SQLAlchemy Setup Verification

Verify that SQLAlchemy is correctly configured and the database connection works.

Verification Steps

1. Check Dependencies

Read requirements.txt or pyproject.toml and verify:

Package	Purpose	Required?
SQLAlchemy or Flask-SQLAlchemy	ORM	Yes
alembic or Flask-Migrate	Migrations	Recommended
Database driver (psycopg2, pymysql, etc.)	DB connection	Yes for PostgreSQL/MySQL

SQLite needs no driver — it's built into Python.

2. Check Database URI

Verify the connection string format:

# SQLite (file-based)
'sqlite:///instance/app.db'
'sqlite:///path/to/database.db'
'sqlite:///:memory:'  # In-memory (testing)

# PostgreSQL
'postgresql://user:password@host:5432/dbname'
'postgresql+psycopg2://user:password@host/dbname'

# MySQL
'mysql+pymysql://user:password@host/dbname'

Ensure the URI comes from environment variables, not hardcoded:

# Good
SQLALCHEMY_DATABASE_URI = os.environ.get('DATABASE_URL', 'sqlite:///app.db')

# Bad
SQLALCHEMY_DATABASE_URI = 'postgresql://admin:[e-mail]/mydb'

3. Check Initialization Pattern

For Flask-SQLAlchemy:

# models.py — create db instance
db = SQLAlchemy()

# app.py — bind to app in factory
def create_app():
    app = Flask(__name__)
    db.init_app(app)
    with app.app_context():
        db.create_all()
    return app

For standalone SQLAlchemy:

from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, DeclarativeBase

engine = create_engine(DATABASE_URL)
Session = sessionmaker(bind=engine)

class Base(DeclarativeBase):
    pass

4. Check Model Definitions

Verify models have:

• Primary key defined
• Proper column types and constraints
• Relationships with correct foreign keys
• __tablename__ set explicitly

5. Common Setup Issues

Issue	Symptom	Fix
No database file	OperationalError: unable to open database	Run db.create_all() or flask db upgrade
Wrong driver	ModuleNotFoundError: No module named 'psycopg2'	Install the database driver package
No SQLALCHEMY_TRACK_MODIFICATIONS	Deprecation warning	Set app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
Missing app context	RuntimeError: Working outside of application context	Wrap in with app.app_context():
No migrations	Schema changes drop data	Install Flask-Migrate and run flask db init

What This Skill Does NOT Cover

• Flask application structure (see flask-dev plugin)
• Deployment database setup (belongs in project template)
• Database administration (see postgresql-provision plugin)