FastAPI is a modern, high-performance web framework for building APIs with Python 3.7+. It is designed to make it easy to create robust, scalable, and fast APIs. FastAPI leverages Python’s type hints to provide automatic data validation and documentation, making it both powerful and developer-friendly.
Key Features of FastAPI:
- High Performance: FastAPI is one of the fastest Python frameworks available, due to its asynchronous capabilities and reliance on Starlette for the web parts.
- Automatic Interactive API Documentation: FastAPI generates interactive API documentation using Swagger UI and ReDoc, making it easy to explore and test your API endpoints.
- Data Validation: It uses Pydantic for data validation, ensuring that incoming data adheres to defined schemas.
- Type Hints: FastAPI utilizes Python’s type hints to provide editor support, data validation, and automatic documentation.
1.2 Why Use FastAPI?
- Performance: FastAPI is built on Starlette and Pydantic, which are designed for performance. This makes FastAPI a suitable choice for high-performance applications.
- Ease of Use: FastAPI’s automatic validation and documentation features reduce the need for boilerplate code and manual documentation, which speeds up development.
- Scalability: FastAPI’s asynchronous support allows for handling many concurrent requests efficiently, making it suitable for high-traffic applications.
1.3 Comparison with Other Frameworks
FastAPI vs. Flask:
- Asynchronous Support: FastAPI supports asynchronous request handling out-of-the-box, whereas Flask does not.
- Automatic Validation and Documentation: FastAPI generates interactive documentation automatically, while Flask requires additional libraries and manual setup.
FastAPI vs. Django:
- Microservices vs. Monolithic: FastAPI is more suited for building microservices due to its lightweight nature, whereas Django is a full-stack framework with built-in ORM and admin panels.
- Performance: FastAPI typically outperforms Django in API-only use cases due to its asynchronous capabilities.
1.4 Getting Started with FastAPI
Installation
To start using FastAPI, you’ll need to install it along with Uvicorn, an ASGI server for running FastAPI applications.
pip install fastapi uvicornCreating Your First FastAPI Application
Here’s a simple FastAPI application to get you started:
# app/main.py
from fastapi import FastAPI
app = FastAPI()
@app.get("/")
def read_root():
return {"message": "Hello, World!"}Running Your Application
To run your FastAPI application, use Uvicorn:
uvicorn app.main:app --reloadThe --reload option is useful for development as it automatically reloads the server when code changes.
1.5 Understanding the Code
FastAPI Instance:
app = FastAPI()The FastAPI class is the core of your application. You create an instance of it to define your application and its routes.
Route Definition:
@app.get("/")
def read_root():
return {"message": "Hello, World!"}The @app.get("/") decorator defines a route for HTTP GET requests to the root path. The function read_root() is called when this route is accessed and returns a JSON response with a “Hello, World!” message.
Interactive API Documentation:
Once your server is running, you can access the interactive API documentation at:
Summary
In this chapter, you have learned the basics of FastAPI, including its key features, how it compares to other frameworks, and how to create and run a basic FastAPI application. FastAPI’s performance and ease of use make it an excellent choice for modern web APIs. In the following chapters, we will dive deeper into more advanced features and practical applications of FastAPI.
