Getting Started with FastAPI: Creating Your First Web App with a Python Tutorial

In this tutorial, we will be building our first web app using FastAPI, a modern, fast (high-performance), web framework for building APIs with Python 3.6+ based on standard Python type hints. FastAPI is built on top of Starlette for the web parts and Pydantic for the data validation and serialization parts.

Prerequisites:

• Python 3.6+
• pip (Python package installer)

Step 1: Install FastAPI and Uvicorn

First, we need to install FastAPI and Uvicorn, which is a lightning-fast ASGI server implementation, using the following pip commands:

pip install fastapi
pip install uvicorn

Step 2: Create a FastAPI App

Create a new Python file, for example, app.py, and import the necessary modules:

from fastapi import FastAPI
app = FastAPI()

Step 3: Define a Path Operation

Define a path operation using a decorators such as @app.get() or @app.post(). For example, let’s create a basic "Hello World" API:

@app.get("/")
def read_root():
    return {"Hello": "World"}

Step 4: Run the FastAPI App

To run the FastAPI app, use Uvicorn with the following command:

uvicorn app:app --reload

This command tells Uvicorn to run the app module and use the app FastAPI instance. The --reload flag enables hot-reloading, which means that the server will automatically reload when you make changes to your code.

Step 5: Test the API

Open your browser or a REST client like Postman and navigate to http://localhost:8000 to see the "Hello World" response.

Congratulations! You have built your first web app using FastAPI. You can now explore more features such as request validation, dependency injection, and more.

Additional Resources:

• FastAPI Documentation: https://fastapi.tiangolo.com/
• Starlette Documentation: https://www.starlette.io/
• Pydantic Documentation: https://pydantic-docs.helpmanual.io/

I hope this tutorial was helpful for you to get started with building web apps using FastAPI. Happy coding!