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fastapi python

FastAPI is a modern, high-performance, web framework for building APIs with Python. It is designed to make it easy to develop APIs quickly and efficiently, with features like automatic validation, serialization, and documentation generation. Here are some key features and concepts related to FastAPI:

  1. Fast: FastAPI is built on top of Starlette for asynchronous request handling, making it highly performant. It takes advantage of Python 3.6+ async and await syntax to handle concurrent connections efficiently.
  2. Type Annotations: FastAPI leverages Python type hints to automatically generate API documentation and validate request and response data. This makes it easy to create well-documented APIs with minimal effort.
  3. Automatic Validation: FastAPI automatically validates incoming request data against defined data models using Pydantic models. If there are validation errors, it returns appropriate error responses.
  4. Automatic API Documentation: FastAPI generates interactive API documentation (Swagger UI and ReDoc) based on your code and type annotations. This documentation is easy to browse and test directly from your browser.
  5. Dependency Injection: You can use dependency injection to manage the logic and data required for handling requests. This allows you to keep your code modular and maintainable.
  6. Authentication and Authorization: FastAPI supports various authentication methods and authorization checks, making it suitable for building secure APIs.
  7. WebSocket Support: In addition to traditional HTTP routes, FastAPI supports WebSocket routes, enabling real-time communication.
  8. Middleware: You can use middleware to perform tasks like logging, authentication, and request/response modification.

Here’s a basic example of creating a FastAPI application:

from fastapi import FastAPI

app = FastAPI()

async def read_root():
    return {"message": "Hello, World!"}

async def read_item(item_id: int, query_param: str = None):
    return {"item_id": item_id, "query_param": query_param}

In this example, we import FastAPI, create an instance of the FastAPI class, and define two API routes using Python’s async functions. The type hints in the function parameters automatically generate documentation and perform data validation.

To run a FastAPI application, you typically use a web server like Uvicorn:

uvicorn main:app --host --port 8000

This command runs the FastAPI application defined in a file named and listens on port 8000.

FastAPI is a powerful and feature-rich framework for building APIs in Python, and it has gained popularity in the Python community for its developer-friendly features and high performance.

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