[Solved] Identify the error in this WSGI middleware implementation: class BrokenMiddleware: def __init__(self, app): self.app = app def __call__(self, environ, start_response):... | Flask

Flask - Middleware and Extensions

Identify the error in this WSGI middleware implementation:

class BrokenMiddleware:
    def __init__(self, app):
        self.app = app
    def __call__(self, environ, start_response):
        # Forgot to call the wrapped app
        return 'Hello'

AMiddleware must call the wrapped app and return its response

BMiddleware should not have an __init__ method

CMiddleware should return a Flask response object, not a string

DMiddleware must not accept environ and start_response parameters

Step-by-Step Solution

Solution:

Step 1: Check middleware call method
The __call__ method must call the wrapped app with environ and start_response to get the response.
Step 2: Identify missing call
This code returns a string directly and does not call the wrapped app, breaking the WSGI chain.
Final Answer:
Middleware must call the wrapped app and return its response -> Option A
Quick Check:
Middleware must call wrapped app [OK]

Quick Trick: Middleware must call and return wrapped app response [OK]

Common Mistakes:

MISTAKES

Returning a string instead of calling app
Removing __init__ method unnecessarily
Misunderstanding WSGI call signature

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More Flask Quizzes

Identify the error in this WSGI middleware implementation:

Step 1: Check middleware call method

Step 2: Identify missing call

Final Answer:

Quick Check:

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