FastAPI SQLAlchemy Models Concepts

Learning objective: By the end of this lesson, you will be able to understand the purpose of SQLAlchemy models in a Python application.

What is SQLAlchemy?

SQLAlchemy is a tool that helps Python developers interact with databases more easily. It is called an Object-Relational Mapper (ORM) because it “maps” (or translates) data stored in a database into Python objects, and vice versa.

What Does That Mean?

Normally, to work with a database, you would write SQL queries to add, retrieve, update, or delete data.
With SQLAlchemy, you don’t need to write SQL directly. Instead, you can work with Python objects, and SQLAlchemy will handle the behind-the-scenes process of translating your actions into SQL statements.

Here’s a visual of how this works:

SQLAlchemy ORM

SQL Records (rows in a database) ↔ Python Objects (instances of classes in Python)

SQLAlchemy takes care of the complex details of communicating with the database so you can focus on writing Python code to manipulate data.

Why use SQLAlchemy?

Benefit	Description
Simplicity	Interact with your database using Python code instead of raw SQL.
Maintainability	Easier to read and maintain, with less complex SQL embedded in the code.
Portability	Switching databases (ex: from SQLite to PostgreSQL) is simpler because your code is less dependent on specific SQL dialects
Safety	Protects against SQL injection attacks by using parameterized queries.

Next steps: Preparing the data layer of the API

First, we’re going to be writing some models to represent our Tea data using SQLAlchemy.
Then we’re then going to be writing a small Python script, called seed.py. This little program will be able to put some initial data into our SQL Database, using our models.

Let’s get started!