Flask Data Persistence

Managing state is at the heart of any web app. This skill focuses on the SQLAlchemy ORM.

Models & relationships

• Declarative Base: Defining tables as Python classes.
• Relationships: Using db.relationship for One-to-Many and Many-to-Many mappings.

Migrations (Flask-Migrate)

Never manually edit your database schema. Use migrations.

1. init: flask db init
2. generate: flask db migrate -m "Added user bio"
3. apply: flask db upgrade

Performance

• Lazy Loading: Understanding select, joined, and subquery loading strategies to avoid N+1 problems.
• Pagination: Use paginate() for manageable data display.