Introduction to FastAPI: A Beginner’s Guide

FastAPI is a modern web framework for building APIs with Python. It is fast, easy to use, and highly efficient, making it a popular choice among developers. In this tutorial, we will cover the basics of FastAPI and show you how to create a simple API with it.

To get started with FastAPI, you will need to have Python installed on your machine. You can download and install Python from the official website. Once Python is installed, you can install FastAPI using pip, Python’s package manager. Open a terminal or command prompt and run the following command:

pip install fastapi

After installing FastAPI, you will also need to install a tool called uvicorn to run the FastAPI application. You can install uvicorn using pip as well:

pip install uvicorn

Now that you have FastAPI and uvicorn installed, let’s create a simple API using FastAPI. Create a new Python file, for example app.py, and open it in your favorite code editor. In this file, write the following code to create a basic FastAPI application:

from fastapi import FastAPI

app = FastAPI()

@app.get('/')
async def read_root():
    return {'message': 'Hello, World!'}

In this code snippet, we first import the FastAPI class from the fastapi module. We then create an instance of the FastAPI class called app. Next, we define a route for the root URL (/) using the @app.get decorator. The read_root function will be invoked whenever a GET request is made to the root URL, and it will return a JSON response with the message ‘Hello, World!’.

To run the FastAPI application, open a terminal or command prompt, navigate to the directory where your app.py file is located, and run the following command:

uvicorn app:app --reload

This command tells uvicorn to run the app object defined in the app.py file, with auto-reloading enabled. You should see output similar to the following:

INFO: Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)

Now that your FastAPI application is running, you can open a web browser and navigate to http://127.0.0.1:8000/ to see your API in action. You should see a JSON response with the message ‘Hello, World!’.

FastAPI supports automatic generation of API documentation using the OpenAPI standard. To view the generated documentation for your API, navigate to http://127.0.0.1:8000/docs in your web browser. You will see an interactive documentation page where you can explore your API endpoints and make test requests.

In this tutorial, you learned the basics of FastAPI and how to create a simple API using it. FastAPI offers many more features and capabilities, such as request validation, dependency injection, and more. I encourage you to explore the FastAPI documentation to learn more about what you can do with this powerful web framework. Happy coding!