DEBUG mode behavior in Django - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when DEBUG is set to True in Django?

In a Django project, if you set DEBUG = True in settings.py, what is the expected behavior when an error occurs during a request?

A Django disables all middleware and serves static files only.

B Django shows a detailed error page with stack trace and local variables.

C Django silently logs the error and shows a generic 500 error page to the user.

D Django redirects the user to the homepage without any error message.

💡 Hint

Think about what helps developers find bugs during development.

When DEBUG is True, Django shows a detailed error page with the stack trace and local variables to help developers debug issues.

📝 Syntax

intermediate

Which setting causes Django to serve static files automatically?

In Django, when DEBUG is set to True, which of the following is true about serving static files during development?

A Django disables static file serving when DEBUG is True.

B Django requires manual configuration of static file serving regardless of DEBUG.

C Django automatically serves static files using <code>django.contrib.staticfiles</code> app.

D Django serves static files only if <code>STATIC_ROOT</code> is empty.

💡 Hint

Think about what makes development easier without extra setup.

When DEBUG is True, Django serves static files automatically using the django.contrib.staticfiles app, simplifying development.

🔧 Debug

advanced

What error occurs if DEBUG is False but ALLOWED_HOSTS is empty?

In Django, if DEBUG = False and ALLOWED_HOSTS = [], what happens when you try to access the site?

A Django serves the site normally without any error.

B Django redirects all requests to the admin login page.

C Django shows the detailed debug error page with stack trace.

D Django raises a <code>DisallowedHost</code> exception and returns a 400 Bad Request error.

💡 Hint

Think about security restrictions when DEBUG is off.

When DEBUG is False, Django requires ALLOWED_HOSTS to be set. If empty, it raises a DisallowedHost exception and returns a 400 error.

❓ state_output

advanced

How does DEBUG mode affect template caching in Django?

When DEBUG is True, how does Django handle template loading compared to when DEBUG is False?

A Templates are reloaded on every request to reflect changes immediately.

B Templates are cached and never reloaded until the server restarts.

C Templates are compiled to bytecode and stored permanently on disk.

D Templates are disabled and replaced with plain HTML files.

💡 Hint

Think about what helps developers see changes quickly.

With DEBUG=True, Django reloads templates on every request so developers see changes immediately without restarting the server.

🧠 Conceptual

expert

Why should DEBUG never be True in production?

Which of the following is the main reason to never set DEBUG = True in a production Django environment?

A It exposes sensitive information like secret keys and database credentials in error pages.

B It disables all middleware, causing security holes.

C It automatically deletes user data after errors occur.

D It prevents the server from handling HTTPS requests.

💡 Hint

Think about what information error pages show when debugging is on.

DEBUG=True shows detailed error pages that can reveal sensitive data, which attackers could exploit. This is why it must be off in production.

Practice

1. What is the main purpose of setting DEBUG = True in a Django project?

easy

A. To enable database backups automatically

B. To improve website speed in production

C. To disable all logging

D. To show detailed error messages during development

Solution

1. Step 1: Understand the role of DEBUG in Django

   DEBUG mode is designed to help developers by showing detailed error messages and debugging information.

2. Step 2: Identify the correct purpose

   Setting DEBUG = True enables detailed error pages, which is useful only during development, not production.

3. Final Answer:

   To show detailed error messages during development -> Option D

4. Quick Check:

   DEBUG = True shows errors [OK]

Hint: DEBUG = True means show errors for fixing [OK]

Common Mistakes:

• Thinking DEBUG improves production speed
• Confusing DEBUG with logging settings
• Assuming DEBUG enables backups

2. Which of the following is the correct way to disable debug mode in Django's settings.py?

easy

A. DEBUG = False

B. DEBUG = 'False'

C. debug = False

D. DEBUG = 0

Solution

1. Step 1: Check the correct syntax for boolean in Python

   In Python, boolean values are capitalized: True or False without quotes.

2. Step 2: Identify the correct assignment in settings.py

   DEBUG must be assigned the boolean False, not a string or lowercase variable.

3. Final Answer:

   DEBUG = False -> Option A

4. Quick Check:

   Boolean False without quotes disables debug [OK]

Hint: Use capitalized False without quotes to disable debug [OK]

Common Mistakes:

• Using 'False' as a string instead of boolean
• Using lowercase debug variable
• Assigning numeric 0 instead of False

3. Given the following Django settings snippet:

DEBUG = True
ALLOWED_HOSTS = []

What will happen if you access the site from a browser?

medium

A. The site will redirect to a login page

B. The site will show a detailed error page if an error occurs

C. The site will run normally without errors

D. The site will block all hosts and show a 400 error

Solution

1. Step 1: Understand DEBUG and ALLOWED_HOSTS interaction

   When DEBUG is True, Django ignores ALLOWED_HOSTS restrictions and shows detailed errors.

2. Step 2: Predict behavior on error

   If an error occurs, Django will display a detailed debug page to help fix it.

3. Final Answer:

   The site will show a detailed error page if an error occurs -> Option B

4. Quick Check:

   DEBUG True shows detailed errors despite ALLOWED_HOSTS [OK]

Hint: DEBUG True overrides ALLOWED_HOSTS for errors [OK]

Common Mistakes:

• Thinking ALLOWED_HOSTS blocks access when DEBUG is True
• Assuming no error page shows
• Confusing error page with login redirect

4. You set DEBUG = False but still see detailed error pages in production. What is the most likely cause?

medium

A. DEBUG must be set to a string 'False'

B. You forgot to set ALLOWED_HOSTS properly

C. You need to restart the Django server

D. You need to clear browser cache

Solution

1. Step 1: Recall DEBUG False behavior

   When DEBUG is False, detailed error pages should not appear. If they do, the setting likely didn't take effect.

2. Step 2: Identify common mistake

   Changes to settings.py require restarting the Django server to reload the configuration.

3. Final Answer:

   You need to restart the Django server -> Option C

4. Quick Check:

   Restart server after settings changes [OK]

Hint: Restart Django server after changing DEBUG [OK]

Common Mistakes:

• Using string 'False' instead of boolean
• Not restarting server after changes
• Assuming browser cache causes error pages

5. You want to deploy your Django app safely. Which combination of settings is best practice for production?

hard

A. DEBUG = False and ALLOWED_HOSTS set to your domain names

B. DEBUG = False and ALLOWED_HOSTS = []

C. DEBUG = True and ALLOWED_HOSTS = ['*']

D. DEBUG = True and ALLOWED_HOSTS set to your domain names

Solution

1. Step 1: Understand production safety rules

   In production, DEBUG must be False to avoid exposing sensitive info.

2. Step 2: Set ALLOWED_HOSTS correctly

   ALLOWED_HOSTS must list your domain names to restrict access and prevent host header attacks.

3. Step 3: Evaluate options

   Only DEBUG = False with proper ALLOWED_HOSTS is safe for production.

4. Final Answer:

   DEBUG = False and ALLOWED_HOSTS set to your domain names -> Option A

5. Quick Check:

   Production needs DEBUG False + correct ALLOWED_HOSTS [OK]

Hint: Production: DEBUG False + real domains in ALLOWED_HOSTS [OK]

Common Mistakes:

• Leaving DEBUG True in production
• Using wildcard '*' in ALLOWED_HOSTS
• Leaving ALLOWED_HOSTS empty