Template filters (date, length, default) in Django - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to format the date using the Django template date filter.

Django

{{ post.published_date|[1] }}

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

Adefault:"N/A"

Blength

Cdate:"Y-m-d"

Dupper

Attempts:

3 left

💡 Hint

Common Mistakes

Using the length filter instead of date.

Forgetting to include the format string in quotes.

The date filter formats a date object. Here, "Y-m-d" formats the date as year-month-day.

2fill in blank

medium

Complete the code to get the length of the list using the Django template length filter.

Django

{{ user.friends|[1] }}

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

Alength

Bdate:"Y"

Cdefault:"0"

Dlower

Attempts:

3 left

💡 Hint

Common Mistakes

Using date filter on a list.

Using default filter instead of length.

The length filter returns the number of items in a list or string.

3fill in blank

hard

Fix the error in the code to provide a default value if the variable is empty.

Django

{{ user.nickname|[1] }}

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

Aupper

Blength

Cdate:"d M Y"

Ddefault:"Anonymous"

Attempts:

3 left

💡 Hint

Common Mistakes

Using length filter instead of default.

Not including quotes around the default value.

The default filter shows a fallback value if the variable is empty or undefined.

4fill in blank

hard

Fill both blanks to format the date and provide a default if the date is missing.

Django

{{ event.start_date|[1]|[2] }}

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

Adate:"M d, Y"

Bdefault:"Date not set"

Clength

Dupper

Attempts:

3 left

💡 Hint

Common Mistakes

Reversing the order of filters.

Using length filter instead of default.

First, the date filter formats the date. Then, default shows a message if the date is missing.

5fill in blank

hard

Fill all three blanks to get the length of a list, provide a default if empty, and convert the result to a string.

Django

{{ items|[1]|[2]|[3] }}

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

Alength

Bdefault:"0"

Cstringformat:"%s"

Ddate:"Y"

Attempts:

3 left

💡 Hint

Common Mistakes

Using date filter instead of stringformat.

Not chaining filters in correct order.

First, length counts items. Then, default sets '0' if empty. Finally, stringformat:"%s" converts the number to a string.

Practice

1. What does the Django template filter length do when applied to a list variable?

easy

A. It returns the number of items in the list.

B. It changes the list into a string.

C. It formats the list as a date.

D. It provides a default value if the list is empty.

Solution

1. Step 1: Understand the purpose of the length filter

   The length filter counts how many items are in a list or string.

2. Step 2: Apply the filter to a list variable

   When used on a list, it returns the count of elements inside it.

3. Final Answer:

   It returns the number of items in the list. -> Option A

4. Quick Check:

   length counts items [OK]

Hint: Remember: length counts items, not changes data type [OK]

Common Mistakes:

• Thinking length changes data format
• Confusing length with default filter
• Assuming length formats dates

2. Which of the following is the correct syntax to use the default filter in a Django template to show 'N/A' if a variable user_name is empty?

easy

A. {{ user_name | default:N/A }}

B. {{ user_name | default('N/A') }}

C. {{ user_name | default:'N/A' }}

D. {{ user_name | default=N/A }}

Solution

1. Step 1: Recall the syntax for filters with arguments

   Filters use the pipe symbol and arguments are passed with a colon and quotes for strings.

2. Step 2: Identify the correct syntax for default

   The correct syntax is {{ variable | default:'value' }} using single or double quotes inside the colon.

3. Final Answer:

   {{ user_name | default:'N/A' }} -> Option C

4. Quick Check:

   Use colon and quotes for filter arguments [OK]

Hint: Use colon and quotes for filter arguments [OK]

Common Mistakes:

• Using parentheses instead of colon
• Omitting quotes around string argument
• Using equal sign instead of colon

3. Given the template code:

{{ my_date|date:"Y-m-d" }}

and my_date is a Python datetime object representing March 5, 2024, what will be the output?

medium

A. 2024-03-05

B. 03/05/2024

C. March 5, 2024

D. 05-03-2024

Solution

1. Step 1: Understand the date filter format string

   The format string "Y-m-d" means 4-digit year, dash, 2-digit month, dash, 2-digit day.

2. Step 2: Apply the format to the date March 5, 2024

   Year is 2024, month is 03, day is 05, so output is "2024-03-05".

3. Final Answer:

   2024-03-05 -> Option A

4. Quick Check:

   Date format Y-m-d = 2024-03-05 [OK]

Hint: Match format letters to date parts exactly [OK]

Common Mistakes:

• Confusing month and day order
• Ignoring leading zeros
• Using wrong format letters

4. What is wrong with this Django template code?

{{ items|length:'default' }}

Assuming items is a list variable.

medium

A. The default filter should be used instead of length.

B. The variable items must be converted to string first.

C. The colon should be replaced with a pipe symbol.

D. The length filter does not take any arguments.

Solution

1. Step 1: Check the usage of length filter

   The length filter counts items and does not accept any arguments.

2. Step 2: Identify the error in the code

   Passing 'default' as an argument with colon is invalid syntax for length.

3. Final Answer:

   The length filter does not take any arguments. -> Option D

4. Quick Check:

   length has no arguments [OK]

Hint: Remember: length filter never takes arguments [OK]

Common Mistakes:

• Trying to pass default value to length
• Confusing filter argument syntax
• Using colon incorrectly with length

5. In a Django template, you want to display the length of a list users, but if the list is empty or undefined, show 'No users'. Which template code achieves this correctly?

hard

A. {{ users|default:'No users'|length }}

B. {{ users|length|default:'No users' }}

C. {{ users|length:'No users' }}

D. {{ users|default:'No users' }} (length missing)

Solution

1. Step 1: Understand filter order and behavior

   First, length counts items in users. If users is empty or undefined, length returns 0 or errors.

2. Step 2: Use default after length to provide fallback

   Applying default:'No users' after length replaces empty or zero output with 'No users'.

3. Final Answer:

   {{ users|length|default:'No users' }} -> Option B

4. Quick Check:

   Chain length then default for fallback [OK]

Hint: Apply length first, then default for fallback text [OK]

Common Mistakes:

• Applying default before length (wrong fallback)
• Passing argument to length filter
• Omitting length filter when counting