URL parameters with angle brackets in Django - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Django URL pattern match?

Given the URL pattern path('item/<int:id>/', view_function) and a request to /item/42/, what value does the view receive for id?

Django

from django.urls import path

def view_function(request, id):
    return id

urlpatterns = [
    path('item/<int:id>/', view_function),
]

A The view receives the string '42'

B The view receives the integer 42

C The view receives None

D The view raises a ValueError

💡 Hint

Remember that <int:id> converts the URL part to an integer before passing it.

The <int:id> converter in Django URL patterns parses the URL segment as an integer and passes it as an int to the view.

📝 Syntax

intermediate

Which URL pattern syntax is correct to capture a string parameter named 'username'?

Choose the correct Django URL pattern syntax to capture a string parameter called username.

A path('user/<str:username>/', user_view)

B path('user/username/', user_view)

C path('user/<string:username>/', user_view)

D path('user/<text:username>/', user_view)

💡 Hint

Django uses specific converters like str, int, slug.

The correct syntax uses <str:username> to capture a string parameter named username.

🔧 Debug

advanced

Why does this URL pattern cause a 404 error for /product/abc123/?

Given the URL pattern path('product/<int:product_id>/', product_view), why does accessing /product/abc123/ cause a 404 error?

Django

urlpatterns = [
    path('product/<int:product_id>/', product_view),
]

A Because 'abc123' is not an integer, so the pattern does not match

B Because the URL pattern should use <str:product_id> instead

C Because the URL is missing a trailing slash

D Because the view function is missing

💡 Hint

Check what the <int:product_id> converter expects.

The <int:product_id> converter only matches digits. 'abc123' contains letters, so the URL pattern does not match and Django returns 404.

❓ state_output

advanced

What is the value of 'slug' captured by this URL pattern?

Given the URL pattern path('blog/<slug:slug>/', blog_view) and a request to /blog/hello-world-2024/, what is the value of slug passed to the view?

A 'hello/world/2024'

B 'hello world 2024'

C 'hello_world_2024'

D 'hello-world-2024'

💡 Hint

The slug converter matches letters, numbers, underscores, and hyphens.

The slug converter captures the URL part as a string containing letters, numbers, underscores, or hyphens. The value is 'hello-world-2024'.

🧠 Conceptual

expert

What happens when using angle brackets without specifying a converter in Django URL patterns?

Consider the URL pattern path('page/<page_num>/', page_view). What behavior occurs?

A Django raises a ValueError about invalid path converter syntax

B Django raises a TypeError in the view function

C Django treats 'page_num' as a string parameter by default

D Django ignores the angle brackets and matches literally

💡 Hint

Angle brackets without a colon (<param>) default to the str converter.

Django treats <page_num> (without a converter and colon) as using the default str converter for the 'page_num' parameter.

Practice

1. What does the angle bracket syntax <int:id> in a Django URL pattern do?

easy

A. Creates a static URL segment named 'int:id'.

B. Specifies a query parameter instead of a URL segment.

C. Defines a string variable named 'id' without type conversion.

D. Captures a part of the URL as an integer variable named 'id'.

Solution

1. Step 1: Understand angle brackets in Django URLs

   Angle brackets capture parts of the URL as variables to pass to views.

2. Step 2: Recognize the converter and variable name

   The syntax <int:id> captures an integer named 'id'.

3. Final Answer:

   Captures a part of the URL as an integer variable named 'id'. -> Option D

4. Quick Check:

   URL parameter with <int:id> = integer variable capture [OK]

Hint: Angle brackets capture URL parts as typed variables [OK]

Common Mistakes:

• Thinking it creates a static URL segment
• Confusing query parameters with URL parameters
• Ignoring the type converter like int or str

2. Which of the following is the correct syntax to capture a slug parameter named 'post_slug' in a Django URL pattern?

easy

A. path('post/<str:post_slug>/', views.post_detail)

B. path('post/<slug:post_slug>/', views.post_detail)

C. path('post/<post_slug:slug>/', views.post_detail)

D. path('post/<slug>post_slug/', views.post_detail)

Solution

1. Step 1: Identify correct converter and variable order

   The correct syntax is <converter:variable_name>, so <slug:post_slug> is correct.

2. Step 2: Check the full path syntax

   path('post/<slug:post_slug>/', views.post_detail) uses path('post/<slug:post_slug>/', views.post_detail), which is valid Django syntax.

3. Final Answer:

   path('post/<slug:post_slug>/', views.post_detail) -> Option B

4. Quick Check:

   Converter before variable name = path('post/<slug:post_slug>/', views.post_detail) [OK]

Hint: Use <converter:variable> format for URL parameters [OK]

Common Mistakes:

• Swapping converter and variable name
• Missing colon between converter and variable
• Using invalid syntax like <slug>post_slug

3. Given this URL pattern: path('user/<int:user_id>/', views.profile), what will user_id be if the URL is /user/42/?

medium

A. A slug '42'

B. The string '42'

C. The integer 42

D. A syntax error occurs

Solution

1. Step 1: Understand the int converter effect

   The <int:user_id> converter converts the URL segment to an integer.

2. Step 2: Apply to the URL segment '42'

   The string '42' from the URL is converted to the integer 42 before passing to the view.

3. Final Answer:

   The integer 42 -> Option C

4. Quick Check:

   int converter converts URL part to integer [OK]

Hint: int converter makes URL part an integer, not string [OK]

Common Mistakes:

• Assuming the parameter is a string
• Confusing slug with int converter
• Expecting a syntax error for valid syntax

4. Identify the error in this Django URL pattern: path('article/<int:id>', views.detail)

medium

A. Missing closing angle bracket '>' after 'id'.

B. Using 'int' converter instead of 'str'.

C. View function 'detail' is not imported.

D. URL pattern should not use angle brackets.

Solution

1. Step 1: Check angle bracket syntax

   The pattern uses <int:id> without the closing '>' character, which is invalid syntax.

2. Step 2: Confirm correct syntax

   The correct syntax requires both opening and closing angle brackets: <int:id>.

3. Final Answer:

   Missing closing angle bracket '>' after 'id'. -> Option A

4. Quick Check:

   Angle brackets must be complete <int:id> [OK]

Hint: Always close angle brackets in URL parameters [OK]

Common Mistakes:

• Forgetting the closing '>'
• Confusing converter types
• Assuming view import errors cause syntax issues

5. You want to create a URL pattern that captures a username (letters, numbers, underscores) and a post ID (integer). Which of these is the best Django URL pattern?

hard

A. path('profile/<slug:username>/post/<int:post_id>/', views.post_view)

B. path('profile/<str:username>/post/<int:post_id>/', views.post_view)

C. path('profile/<int:username>/post/<int:post_id>/', views.post_view)

D. path('profile/<username>/post/<post_id>/', views.post_view)

Solution

1. Step 1: Choose correct converter for username

   Usernames usually contain letters, numbers, underscores, so 'slug' converter fits best.

2. Step 2: Confirm integer converter for post ID

   Post ID should be an integer, so <int:post_id> is correct.

3. Step 3: Evaluate options

   path('profile/<slug:username>/post/<int:post_id>/', views.post_view) uses <slug:username> and <int:post_id>, matching requirements perfectly.

4. Final Answer:

   path('profile/<slug:username>/post/<int:post_id>/', views.post_view) -> Option A

5. Quick Check:

   Slug for username + int for post ID = path('profile/<slug:username>/post/<int:post_id>/', views.post_view) [OK]

Hint: Use slug for usernames, int for numeric IDs in URLs [OK]

Common Mistakes:

• Using str converter which allows spaces
• Using int converter for username
• Omitting converters causing string default