Creating a SQLAlchemy DB instance

SQLAlchemy is a Python SQL toolkit and provides an ORM that gives the flexibility and power of SQL with the feel of Python's object-oriented nature.

Getting ready

Flask-SQLAlchemy is the extension that provides the SQLAlchemy interface for Flask.

This extension can be simply installed using pip as follows:

$ pip install flask-sqlalchemy

The first thing to keep in mind with Flask-SQLAlchemy is the application config parameter that tells SQLAlchemy about the location of the database to be used:

app.config['SQLALCHEMY_DATABASE_URI'] = os.environ('DATABASE_URI')

This SQLALCHEMY_DATABASE_URI is a combination of the database protocol, any authentication needed, and also the name of the database. In the case of SQLite, this would look something like the following:

sqlite:////tmp/test.db

In the case of PostgreSQL, it would look like the following:

postgresql://yourusername:yourpassword@localhost/yournewdb.

This extension then provides a class named Model that helps in...