Unveiling the Power of FastAPI in Python

If you’re developing or interested in API development in Python, chances are you’ve come across FastAPI. It’s a modern, fast (high-performance), web framework for building APIs with Python 3.6+ based on standard Python type hints. In this blog post, we’ll delve into the world of FastAPI, and see why it’s becoming the go-to tool for API development.

Key Features of FastAPI

Before diving in, let’s first look at some of the key features of FastAPI:

1. Speed: FastAPI is on par with NodeJS and addresses HTTP requests at a similar rate to Go, thanks to its non-blocking nature and usage of Starlette for the web parts and Pydantic for the data parts.
2. Data validation: Use Python 3.6+ type declarations for request body parameters, path parameters, and query parameters.
3. Easy to use: FastAPI is designed to be easy and intuitive to use while providing great editor support.
4. Asynchronous support: Python 3.7 brought us the ‘async’ and ‘await’ keywords for handling asynchronous I/O, which FastAPI fully supports.

Setting Up a Basic FastAPI Application

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from fastapi import FastAPI

app = FastAPI()

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

You just built a FastAPI application that responds to HTTP GET requests at the endpoint /.

FastAPI and Pydantic for Data Validation

One of FastAPI’s main features is automatic request validation. Let’s extend our application and introduce some validation.

from pydantic import BaseModel

class Item(BaseModel):
    name: str
    number: int

@app.post("/items/")
def create_item(item: Item):
    return item

In this example, we’ve defined a model Item using Pydantic. The function create_item expects a POST request with a body that matches the structure of Item. If the request doesn’t match, FastAPI will automatically return a helpful error message.

Asynchronous Support

FastAPI supports the creation of asynchronous endpoints out of the box. You can define an async endpoint using the async keyword.

@app.get("/async-endpoint")
async def read_items():
    return {"Hello": "Async World"}

Automatic Documentation with FastAPI

FastAPI automatically generates two types of API documentation. To view them, run your application and visit these URLs:

1. http://localhost:8000/docs (Interactive API documentation)
2. http://localhost:8000/redoc (ReDoc API documentation)

Conclusion

FastAPI shines in its simplicity, speed, and automatic validation and documentation features. If you’re getting started with or are already involved in API development with Python, give FastAPI a spin – it’s a joy to work with!

In the future posts, we will go deeper into advanced features of FastAPI, such as OAuth2 authentication, CORS, Background Tasks, and more. Stay tuned!

References:

• FastAPI documentation: https://fastapi.tiangolo.com