FastAPI MVC CRUD Build Mounting the FastAPI Router

Learning Objective: By the end of this lesson, you will be able to mount routers in a FastAPI project to organize and manage API endpoints efficiently, and test your FastAPI app by making API requests.

Organizing the application with routers

In FastAPI, routers allow us to organize and manage our API endpoints. Instead of having all your endpoints in the main.py file, you can split them into separate modules. This helps keep the code clean and maintainable.

Import the router controller module

We’ve already created the teas controller, which defines the /teas route for retrieving the tea data. Now, we need to include this router into our main application.

Open the main.py file and add the following code:

# main.py

from fastapi import FastAPI
from controllers.teas import router as TeasRouter  # Import the teas router

app = FastAPI()

# Include the teas router with a prefix '/api'
app.include_router(TeasRouter, prefix="/api")


@app.get('/')
def home():
    # Hello world function
    return {'message': 'Hello World!'}

In this code, the line app.include_router(TeasRouter, prefix="/api") does two important things:

1. Mounts the TeasRouter: This makes all the routes defined in the teas controller available to the application.

2. Adds a prefix /api: This means that all routes from the TeasRouter will now be available at paths like /api/teas instead of just /teas.

Testing the API

Now that we’ve organized our code, it’s time to test it!

1. Start the FastAPI server by running the following command in your terminal:

pipenv run uvicorn main:app --reload

1. Open your browser and navigate to http://127.0.0.1:8000/api/teas.

   • This will trigger the GET /api/teas route from the teas controller.

If everything is set up correctly, you should see the following JSON response with the mock tea data:

{
  "teas": [
    { "id": 1, "name": "chai", "in_stock": true, "rating": 4.2 },
    { "id": 2, "name": "lemongrass", "in_stock": true, "rating": 3.8 },
    { "id": 3, "name": "matcha", "in_stock": false, "rating": 4.4 }
  ]
}

Add more routes

Now that your basic setup is complete, it’s time to expand the functionality by adding more routes to your API.

Add a route for a single tea

Let’s say we want to retrieve a specific tea by its id. To do this, we’ll add a new GET route to the teas controller.

1. Open controllers/teas.py and add the following code:

# teas.py

from fastapi import APIRouter
from models.tea_data import teas_db

router = APIRouter()

@router.get("/teas")
def get_teas():
    # Get all teas
    return teas_db

@router.get("/teas/{tea_id}")
def get_single_tea(tea_id: int):
    # Get tea by ID
    for tea in teas_db['teas']:
        if tea['id'] == tea_id:
            return tea
    # If tea with the given ID is not found
    raise HTTPException(status_code=404, detail="Tea not found")

• @router.get("/teas/{tea_id}"): This is a route to handle GET requests for a specific tea by id. The {tea_id} part in the URL is a path parameter that captures the ID of the tea.
• get_tea(tea_id: int): This function looks up the tea by its id from the teas_db mock data. If no tea is found with that ID, it returns a “Tea not found” message.

Testing the new route

1. Start your FastAPI server again if it’s not running:

pipenv run uvicorn main:app --reload

1. Now, navigate to http://127.0.0.1:8000/api/teas/1 in your browser, replacing 1 with the ID of the tea you want to retrieve.

   • You should see the specific tea’s data returned in the same JSON format.

{
  "id": 1,
  "name": "chai",
  "in_stock": true,
  "rating": 4.2
}

In the next steps, you can continue expanding your FastAPI app by adding more routes to handle creating, updating, and deleting teas!