FastAPI: An Introduction to Using FastAPI

FastAPI is a modern, fast (high-performance), web framework for building APIs with Python 3.6+ based on standard Python type hints. It is designed to be easy to use, fast to develop with, and highly performant.

Here are some key features and advantages of FastAPI:

Key Features

• High Performance: FastAPI is one of the fastest Python frameworks available, on par with NodeJS and Go in terms of performance.
• Easy to Use: It provides an easy-to-use interface, reducing the complexity involved in creating API endpoints.
• Automatic Documentation: FastAPI automatically generates interactive API documentation using Swagger UI and ReDoc.
• Type Hints and Validation: It uses Python-type hints to perform data validation and serialization, ensuring type safety and reducing bugs.
• Dependency Injection: Built-in dependency injection system allows for a clean and maintainable codebase.
• Asynchronous Support: Full support for asynchronous programming, which helps in handling a large number of concurrent connections efficiently.
• Standards-Based: It is built on top of standard Python-type hints and the OpenAPI standard, ensuring compatibility and ease of integration with other tools and libraries.

Getting Started

To create a basic API with FastAPI, follow these steps:

1. Install FastAPI and an ASGI server (e.g., uvicorn):

pip install fastapi uvicorn

2. Create a basic FastAPI app:

from fastapi import FastAPI

app = FastAPI()

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

@app.get("/items/{item_id}")
async def read_item(item_id: int, q: str = None):
return {"item_id": item_id, "q": q}

3. Run the application:

uvicorn main:app --reload

#Here, main refers to your Python file (e.g., main.py), and app is the FastAPI instance.

4. Open a Web Browser:

After starting your FastAPI app, open a web browser and navigate to http://127.0.0.1:8000/.

Steps to Access the Documentation

To find the automatically generated API documentation for your FastAPI application, you can access the following URLs after running your FastAPI app.

1. Swagger UI: Provides an interactive API documentation interface.

• URL: /docs
• Example: http://127.0.0.1:8000/docs

2. ReDoc: An alternative interactive API documentation interface.

• URL: /redoc
• Example: http://127.0.0.1:8000/redoc

Customizing Documentation URLs

If you want to customize the paths for the documentation, you can do so by specifying the docs_url and redoc_url parameters when creating your FastAPI app instance:

from fastapi import FastAPI

app = FastAPI(
    docs_url="/my-custom-docs",
    redoc_url="/my-custom-redoc"
)

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

In this example, the Swagger UI documentation would be available at http://127.0.0.1:8000/my-custom-docs and the ReDoc documentation at http://127.0.0.1:8000/my-custom-redoc. By default, FastAPI provides these automatically generated documentation interfaces, making it easy to test and interact with your API endpoints.