Flask-SQLAlchemy

What it is and what it does

Flask-SQLAlchemy is a Flask extension that bridges Flask applications to SQLAlchemy, the Python SQL toolkit and ORM. It provides a db object that wraps SQLAlchemy functionality with Flask-aware defaults—database URI configuration through app.config, automatic session management tied to Flask's request context, and helper methods for common operations like create_all() and session.execute(). The package aims to reduce boilerplate when using SQLAlchemy in Flask by handling context binding and providing a familiar, Flask-style API.

You define database models as classes inheriting from db.Model, using SQLAlchemy's modern declarative syntax (Mapped types, mapped_column). The extension manages the session lifecycle automatically within Flask's application context, so you can focus on defining schemas and writing queries rather than managing connection pools and session cleanup. It supports current Python versions and works with any SQLAlchemy-compatible database backend.

Use it for

• Building REST APIs with Flask where you need ORM-based data models and automatic session handling per request
• Defining and managing database schemas declaratively in Flask applications without manual session boilerplate
• Prototyping web applications that require SQLite or PostgreSQL backends with minimal database configuration overhead
• Integrating SQLAlchemy queries into Flask route handlers while maintaining clean separation of concerns
• Creating Flask admin interfaces or CRUD applications where ORM models map directly to database tables

Worth the install?

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Install

flask-sqlalchemy on PyPI

Before you install

Low install friction with a pure Python wheel distribution. Actively maintained as of 2026-05-18 with 4311 repository stars, indicating stable, well-established tooling.

License in practice

Permissive BSD license allows use in commercial and proprietary projects without copyleft obligations.

Quickstart

pip install Flask-SQLAlchemy

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column

app = Flask(__name__)
app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///example.sqlite"

class Base(DeclarativeBase):
  pass

db = SQLAlchemy(app, model_class=Base)

class User(db.Model):
    id: Mapped[int] = mapped_column(db.Integer, primary_key=True)
    username: Mapped[str] = mapped_column(db.String, unique=True, nullable=False)

with app.app_context():
    db.create_all()
    db.session.add(User(username="example"))
    db.session.commit()

Package facts

Evidence: flask_sqlalchemy-3.1.1-py3-none-any.whl

Tags

More Dynamic Content packages

See also Flask-Alembic · sqlalchemy-mixins · sqlbag · pylint-flask-sqlalchemy · Flask-Session · Flask-Migrate · Flask-Admin · SQLAlchemy · Flask-Mail