Custom middleware creation in Flask - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a Flask middleware class that initializes with the app.

Flask

class CustomMiddleware:
    def __init__(self, [1]):
        self.app = app

Drag options to blanks, or click blank then click option'

Aapp

Brequest

Cself

Dmiddleware

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'request' instead of 'app' as the parameter.

Not accepting any parameter in __init__.

The middleware class needs to accept the app as a parameter to wrap it.

2fill in blank

medium

Complete the code to make the middleware callable by Flask.

Flask

    def __call__(self, [1], start_response):
        return self.app([1], start_response)

Drag options to blanks, or click blank then click option'

Arequest

Bresponse

Cself

Denviron

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'request' instead of 'environ'.

Using 'self' as the first argument.

The __call__ method of middleware receives the WSGI environment dictionary as the first argument.

3fill in blank

hard

Fix the error in the middleware call to pass the correct arguments.

Flask

    def __call__(self, environ, [1]):
        return self.app(environ, start_response)

Drag options to blanks, or click blank then click option'

Astart_response

Bresponse

Cself

Drequest

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'response' or 'request' instead of 'start_response'.

Omitting the second argument.

The second argument to __call__ is the start_response callable used by WSGI.

4fill in blank

hard

Fill both blanks to add a print statement before calling the app.

Flask

    def __call__(self, [1], [2]):
        print("Middleware active")
        return self.app([1], [2])

Drag options to blanks, or click blank then click option'

Aenviron

Bstart_response

Crequest

Dresponse

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'request' or 'response' instead of WSGI parameters.

Swapping the order of arguments.

The __call__ method must accept environ and start_response to work correctly.

5fill in blank

hard

Fill all three blanks to wrap the Flask app with the middleware.

Flask

app = Flask(__name__)
app.wsgi_app = [1](app.[2])

@app.route('/')
def home():
    return [3]

Drag options to blanks, or click blank then click option'

ACustomMiddleware

Bwsgi_app

C"Hello, Middleware!"

Drun

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning middleware directly to app instead of app.wsgi_app.

Returning a function instead of a string in the route.

We wrap the Flask app's wsgi_app with CustomMiddleware and return a string from the route.