Template includes for reusability in Django - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of using template includes in Django?

Template includes let you reuse parts of HTML code across different pages. This helps keep your templates clean and avoids repeating the same code.

beginner

How do you include one template inside another in Django?

Use the {% include 'template_name.html' %} tag inside your main template to insert the content of another template.

intermediate

Can you pass variables to an included template in Django? If yes, how?

Yes, you can pass variables using {% include 'template.html' with var1=value1 var2=value2 %}. The included template can then use these variables.

intermediate

What happens if the included template file does not exist?

Django will raise a TemplateDoesNotExist error unless you use ignore missing like {% include 'file.html' ignore missing %}, which skips the error and shows nothing.

beginner

Why is using template includes better than copying and pasting HTML code?

Using includes means you only update code in one place. This reduces mistakes and saves time when you want to change shared parts like headers or footers.

Which Django template tag is used to insert one template inside another?

A {% include 'template.html' %}

B {% import 'template.html' %}

C {% extend 'template.html' %}

D {% load 'template.html' %}

The correct tag to include a template is {% include 'template.html' %}.

How can you pass a variable named 'user' to an included template?

A {% include 'file.html' with user=user %}

B {% include 'file.html' user=user %}

C {% include 'file.html' set user=user %}

D {% include 'file.html' pass user=user %}

You pass variables using the 'with' keyword: {% include 'file.html' with user=user %}.

What does the 'ignore missing' option do in an include tag?

A It caches the included template

B It loads a default template instead

C It shows an error message on the page

D It skips the error if the included template is missing

'ignore missing' prevents errors if the template file is not found and simply shows nothing.

Why should you use template includes instead of copying HTML code?

A To avoid using CSS

B To make templates load faster

C To keep code DRY and easier to maintain

D To prevent JavaScript errors

Includes help keep code DRY (Don't Repeat Yourself) and easier to update.

Which of these is NOT a valid use of the include tag?

A {% include 'header.html' %}

B {% include 'base.html' extends %}

C {% include 'sidebar.html' ignore missing %}

D {% include 'footer.html' with year=2024 %}

'extends' is a different tag and cannot be combined with include like that.

Explain how template includes improve code reusability in Django projects.

Think about how you would share a header or footer across many pages.

Describe how to pass data to an included template and why it might be useful.

Passing variables lets the included template show different content.

Practice

1. What is the main purpose of using {% include %} in Django templates?

easy

A. To reuse parts of templates like headers or footers in multiple pages

B. To execute Python code inside the template

C. To define variables for use in the template

D. To create loops inside the template

Solution

1. Step 1: Understand the role of {% include %}

   This tag is used to insert reusable template parts, such as headers or footers, into other templates.

2. Step 2: Compare with other template features

   Executing Python code or defining variables is done differently, not with {% include %}.

3. Final Answer:

   To reuse parts of templates like headers or footers in multiple pages -> Option A

4. Quick Check:

   Template reuse = To reuse parts of templates like headers or footers in multiple pages [OK]

Hint: Remember: include = reuse template parts like header/footer [OK]

Common Mistakes:

• Thinking include runs Python code
• Confusing include with variable assignment
• Using include to create loops

2. Which of the following is the correct syntax to include a template named menu.html inside another template?

easy

A. {% include menu.html %}

B. {% include 'menu.html' %}

C. {% include "menu.html %}

D. {% include 'menu' %}

Solution

1. Step 1: Check the syntax for including templates

   The correct syntax requires the template name as a quoted string inside the include tag, like {% include 'menu.html' %}.

2. Step 2: Evaluate the options

   {% include menu.html %} misses quotes, {% include "menu.html %} malformed double quotes (missing closing quote), {% include 'menu' %} misses the file extension.

3. Final Answer:

   {% include 'menu.html' %} -> Option B

4. Quick Check:

   Include syntax = {% include 'menu.html' %} [OK]

Hint: Include template name in single quotes inside {% include %} [OK]

Common Mistakes:

• Forgetting quotes around template name
• Omitting file extension
• Using variable name without quotes

3. Given the following templates:

{% raw %}{# base.html #}%

  
    {% include 'header.html' %}
    
Welcome
  
{% endraw %}

And header.html contains:

{% raw %}
Menu
{% endraw %}

What will be the rendered output of base.html?

medium

A. Error: header.html not found

B.

{% include 'header.html' %}
Welcome

C.

Menu
Welcome

D.

Menu
Welcome

Solution

1. Step 1: Understand how {% include %} works

   The include tag inserts the full content of header.html into base.html at the include position.

2. Step 2: Replace include with header content

   Replacing {% include 'header.html' %} with <header><nav>Menu</nav></header> gives the full HTML output.

3. Final Answer:

   <html> <body> <header><nav>Menu</nav></header> <h1>Welcome</h1> </body> </html> -> Option D

4. Quick Check:

   Include inserts full template content =
   Menu

   Welcome

   [OK]

Hint: Include inserts full content exactly where placed [OK]

Common Mistakes:

• Expecting include tag to remain in output
• Assuming partial content inserted
• Thinking include causes error if file exists

4. You wrote {% include header.html %} in your template but get a TemplateSyntaxError. What is the most likely cause?

medium

A. Missing quotes around the template name in the include tag

B. The header.html file does not exist

C. You need to use {% extends %} instead of {% include %}

D. You forgot to load the include tag library

Solution

1. Step 1: Identify syntax rules for include

   The template name must be a quoted string inside the include tag, like {% include 'header.html' %}.

2. Step 2: Analyze the error cause

   Omitting quotes causes TemplateSyntaxError because Django expects a string literal.

3. Final Answer:

   Missing quotes around the template name in the include tag -> Option A

4. Quick Check:

   Quotes required for template name = Missing quotes around the template name in the include tag [OK]

Hint: Always put template names in quotes inside {% include %} [OK]

Common Mistakes:

• Forgetting quotes around template name
• Confusing include with extends
• Assuming include tag needs loading

5. You want to create a reusable navigation menu that highlights the current page. You have menu.html included in multiple templates. How can you pass the current page name to menu.html using {% include %}?

hard

A. {% include 'menu.html' current_page='home' %}

B. {% include 'menu.html' only current_page='home' %}

C. {% include 'menu.html' with current_page='home' %}

D. {% include 'menu.html' as current_page='home' %}

Solution

1. Step 1: Recall how to pass variables with include

   Django allows passing variables to included templates using with keyword inside the include tag.

2. Step 2: Check syntax correctness

   The correct syntax is {% include 'menu.html' with current_page='home' %}. Other options are invalid syntax.

3. Final Answer:

   {% include 'menu.html' with current_page='home' %} -> Option C

4. Quick Check:

   Pass variables with 'with' keyword = {% include 'menu.html' with current_page='home' %} [OK]

Hint: Use 'with' keyword to pass variables in {% include %} [OK]

Common Mistakes:

• Omitting 'with' keyword when passing variables
• Using 'only' incorrectly with variables
• Trying to assign variables with 'as'