Authentication Hook
Let’s create a simple example where we use a before hook to check for an authentication token in the request headers.
Step 1: Setting Up Falcon
Firstly, install Falcon if you haven’t installed already:
pip install falcon
Step 2: Writing the Hook
Create a file named app.py and start by importing the necessary modules and writing the hook function:
#app.py
import falcon
# Define the authentication hook
def auth_hook(req, resp, resource, params):
token = req.get_header('Authorization')
if token != 'secret-token':
raise falcon.HTTPUnauthorized('Authentication required',
'Please provide a valid token.')
- auth_hook is a function that checks for an Authorization header in the request.
- If the token is not secret-token, it raises an HTTPUnauthorized exception, which results in a 401 Unauthorized response.
Step 3: Creating a Resource
Next, define a resource where the hook will be applied:
#app.py
# Define the resource with request handlers
class ResourceWithAuth:
@falcon.before(auth_hook)
def on_get(self, req, resp):
resp.media = {'message': 'You are authenticated!'}
@falcon.before(auth_hook)
def on_post(self, req, resp):
resp.media = {'message': 'Data received!'}
ResourceWithAuth is a resource class with two methods:
- on_get: Handles GET requests and responds with a JSON message.
- on_post: Handles POST requests and responds with a JSON message.
Step 4: Setting Up the API
Set up the Falcon API and add the route:
#app.py continue...
# Set up the Falcon API and add the route
app = falcon.App()
app.add_route('/secure', ResourceWithAuth())
# Run the application using the built-in WSGI server
if __name__ == '__main__':
from wsgiref.simple_server import make_server
with make_server('', 8000, app) as httpd:
print('Serving on port 8000...')
httpd.serve_forever()
Running the Application
Run your Falcon application, using:
python app.py
You should see the output indicating that the server is running:
output
Python Falcon – Hooks
In Falcon, hooks are type of callbacks that are defined by the user and are executed before or after a responder method in a particular resource class to process client request. They are useful in as much as they allow a client to add or overwrite request processing functionality at certain predefined stages.