Python Falcon – App Class

Python Falcon App class serves as the foundation for creating scalable and efficient web applications. In this article, we’ll discuss the Falcon’s App class, exploring its features, and benefits.

What is Python Falcon – App Class?

Falcon App class is essential for any Falcon-based application. It provides developers with an easy way to define API resources, manage request routing, and incorporate middleware. By using the App class, developers can make their applications effectively, resulting in code that’s both easy to maintain and efficient. To import the Falcon App class in Python, use the below command.

import falcon

Python Falcon – App Class

Python Falcon supports both the WSGI (Web Server Gateway Interface) and ASGI (Asynchronous Server Gateway Interface) protocols. Falcon’s support for both protocols is facilitated by two distinct classes: falcon.App for WSGI applications and falcon.asgi.App for ASGI applications.

• ASGI App Class
• WSGI App Class

Create a Virtual Environment

First, create the virtual environment using the below commands:

python -m venv env 
.\env\Scripts\activate.ps1

Install Necessary Library

Before using Falcon, it is necessary to install the Falcon library by executing the following command in the terminal:

pip install falcon 

ASGI App Class Example

In this example, below Python code creates a Falcon ASGI application that responds with a JSON message when accessed at the /hello endpoint. It utilizes the Falcon framework to define a resource class with an asynchronous on_get method to handle GET requests.

Python3

import falcon
from falcon.asgi import App as ASGIApp


class HelloWorldResource:
    async def on_get(self, req, resp):
        resp.media = {'message': 'Hello, Falcon ASGI!'}


app = ASGIApp()
app.add_route('/hello', HelloWorldResource())

if __name__ == '__main__':
    import uvicorn
    uvicorn.run(app, host='localhost', port=8000)

Output

WSGI App Class Example

In this example, below Python code defines a Falcon WSGI application that responds with a simple text message “Hello, Falcon WSGI!” when accessed at the /hello endpoint. It sets the response status code to 200 OK, content type to plain text, and assigns the message to the response body.

Python3

import falcon

class HelloWorldResource:
    def on_get(self, req, resp):
        resp.status = falcon.HTTP_200
        resp.content_type = 'text/plain'
        resp.text = 'Hello, Falcon WSGI!'

# Create a Falcon application instance
app = falcon.App()

# Add a route to the HelloWorldResource
app.add_route('/hello', HelloWorldResource())

# Run the Falcon application using a WSGI server
if __name__ == '__main__':
    from wsgiref import simple_server

    # Create a WSGI server instance
    httpd = simple_server.make_server('localhost', 8000, app)
    print('Serving on localhost:8000...')
    # Start the server
    httpd.serve_forever()

Output

Python Falcon – App Class Examples

Below are the examples of Python Falcon – App Class:

Create App Class for User Details

In this example, below Python code uses Falcon framework to create two resources for handling user-related requests: UserResource for fetching a list of users and UserProfileResource for retrieving individual user profiles based on their ID. The /users endpoint responds with a list of user data, while /users/{user_id} returns the profile information of a specific user.

Python3

import falcon

class UserResource:
    def on_get(self, req, resp):
        # Logic to fetch and return user data from database
        resp.media = {
            'users': [{'id': 1, 'name': 'Alice'}, {'id': 2, 'name': 'Bob'}]}

class UserProfileResource:
    def on_get(self, req, resp, user_id):
        # Logic to fetch and return user profile data based on user_id
        resp.media = {'user_id': user_id, 'profile': {
            'email': 'alice@example.com', 'age': 30}}

app = falcon.App()
app.add_route('/users', UserResource())
app.add_route('/users/{user_id}', UserProfileResource())

if __name__ == '__main__':
    from wsgiref import simple_server
    httpd = simple_server.make_server('localhost', 8000, app)
    print('Serving on localhost:8000...')
    httpd.serve_forever()

Output

localhost:8000/users

Create App Class for Products

In this example, below Python code sets up a Falcon application to manage product data. It includes two resources: ProductResource for the product catalog and ProductDetailResource for specific product details. The /products endpoint lists products with IDs, names, and prices, while /products/{product_id} provides detailed info.

Python

import falcon

class ProductResource:
    def on_get(self, req, resp):
        # Logic to fetch and return product catalog data from database
        resp.media = {'products': [{'id': 1, 'name': 'Product A', 'price': 20.99},
                                   {'id': 2, 'name': 'Product B', 'price': 15.49}]}

class ProductDetailResource:
    def on_get(self, req, resp, product_id):
        # Logic to fetch and return product details based on product_id
        resp.media = {'product_id': product_id, 'name': 'Product A', 'price': 20.99, 'description': 'Lorem ipsum'}

app = falcon.App()
app.add_route('/products', ProductResource())
app.add_route('/products/{product_id}', ProductDetailResource())

if __name__ == '__main__':
    from wsgiref import simple_server
    httpd = simple_server.make_server('localhost', 8000, app)
    print('Serving on localhost:8000...')
    httpd.serve_forever()

Output

localhost:8000/products

localhost:8000/products/1

Conclusion

In conclusion , The Falcon App class empowers developers to build fast, scalable, and maintainable APIs with ease. Its minimalist design, coupled with powerful features such as resource handling, routing, and middleware support, makes it a preferred choice for API development in Python. By following best practices and leveraging the flexibility of the App class, developers can create exceptional APIs that meet the needs of their users and businesses.