Lesson Complete!

What you learned

• How REST APIs exchange data using requests and responses over HTTP
• The HTTP methods you will use throughout this course: GET, POST, PATCH, and DELETE
• How to install FastAPI and uvicorn to run your API server
• How Pydantic validates incoming data and rejects anything that does not match your model
• How to define an Expense model with field-level constraints like minimum length and allowed categories
• How to write a custom field validator that checks the date format before the data reaches your endpoint

Next up

In the next lesson, you will build your first working endpoint. You will write a POST route that accepts expense data, assigns it a unique identifier, stores it, and returns the result. By the end, you will test it live in FastAPI's built-in Swagger UI.