Python API course: Part #59 – FastAPI Routers

In this tutorial, we will be diving into the concept of FastAPI routers in Python. FastAPI is a modern web framework for building APIs with Python that is known for its speed, simplicity, and type checking capabilities. Routers are a key feature of FastAPI that allow you to organize your API endpoints into reusable components.

Before we get started, make sure you have FastAPI installed in your Python environment. You can install it using pip:

pip install fastapi

You will also need to install a ASGI server like uvicorn to run your FastAPI application:

pip install uvicorn

Now that you have FastAPI installed, let’s create a basic FastAPI application with a router. Create a new Python file, for example app.py, and import the necessary modules:

from fastapi import FastAPI
from fastapi.routing import APIRouter

Next, let’s create our FastAPI app instance and a router instance:

app = FastAPI()
router = APIRouter()

Now, let’s define a couple of endpoints for our API. Create a function that will be the handler for the endpoint, for example:

@router.get("/hello")
async def hello_world():
    return {"message": "Hello, World!"}

In this code snippet, we defined a simple endpoint that responds with a JSON object containing a "message" key with the value "Hello, World!".

Finally, we need to include our router in the FastAPI app instance so that it can handle requests to the endpoint we defined. Add the following line to the app.py file:

app.include_router(router)

Now, you can run your FastAPI app using the uvicorn server:

uvicorn app:app --reload

Navigate to http://127.0.0.1:8000/hello in your web browser, and you should see the JSON response with the message "Hello, World!".

Routers are a powerful feature of FastAPI that allow you to organize your API endpoints into separate modules. This can help keep your codebase clean and manageable, especially as your project grows in complexity. You can create multiple routers and include them in your FastAPI app to partition your routes according to their functionality or purpose.

In this tutorial, we have covered the basics of using routers in FastAPI to create modular API endpoints. You can expand on this foundation by creating more routers, defining additional endpoints, and incorporating more complex logic into your API. FastAPI’s intuitive API design and performance make it a great choice for building web APIs with Python.