Tags in Django Templates

Tags in Django Templates

Tags in Django Templates look like this: {% tag %}. Tags are more complex than variables: Tags can create text in the output, control structure with loops or logic, and load external information into the Django template to be used by later variables.

In Django templates, tags provide arbitrary logic during the rendering process. For example, a tag can output text, serve as a control structure with the help of loops or logic e.g. a ‘for’ loop or an ‘if’ statement. A tag can also grab information from the database.

Given below is an example of the usage of tags in Django templates. The code will print “Hello, {{ user.username }}.”  only if user.is_authenticated is true. {% csrf_token %}, {% if user.is_authenticated %} and {%endif %} are tags while {{ user.username}} is a variable.

{% csrf_token %}  
 
{% if user.is_authenticated %}  
    Hello, {{ user.username }}.  
{% endif %} 

 

Let’s take our user as logged in with a username of ‘Naman’, then the above template will render to:

Hello, Naman.

 

Commonly used Tags in Django Templates

Autoescape :

This tag controls the current auto-escaping behaviour. autoescape tag accepts either on or off as the argument and that determines whether auto-escaping is in effect or not. The block ends with an endautoescape ending tag.

When autoescaping is on, which is the default, the HTML tags in variables will be escaped using HTML entities before placing the result into the output (but after any filters have been applied). 

Example Usage autoescape on:

variable_item = '<p>You are <em>intelligent</em> and smart!</p>'
 
{% autoescape %}  
    { variable_item }  
{% endautoescape %} 

    

Output:

 

Example usage autoescape off:

variable_item = '<p>You are <em>intelligent</em> and smart!</p>'
 
{% autoescape off %}  
    { variable_item }  
{% endautoescape %} 

 

Output:

Comment :

We use Comment tags to comment out code to prevent interpretation of template tags or variables and prevent the content from being delivered. Any content between {% comment %} and {% endcomment %} is ignored by the Django template. Any optional content may be inserted in {% comment <content> %}.

Example Usage:

variable_item = '<p>You are <em>intelligent</em> and smart!</p>'
 
{% comment “should we remove this?” %}  
    { variable_item }  
{% endcomment %}     

 

The above code will comment out everything between {% comment %} and {% endcomment %}. The comment here added is useful for fellow developers.

Cycle and for loop: 

The cycle tag iterates through all of its given arrays one by one and produces an argument every time with the iterated item. It produces the first argument on the first iteration, the second argument on the second iteration, the third argument on the third iteration, etc. Once alliteration is completed the tag cycles to the first iteration again and produces the first argument again.

The {% for %} tag iterates over every item in the array. We can access the item using a context variable.

Example usage: 

seat_arrangement = ['Naman', 'Nisha', 'Rahul', 'Snehal', 'Joy']

<ol> 
{% for all student in seat_arrangement %}  
    <li class="{% cycle 'row1' 'row2' %}">{{ student }}</li>  
{% endfor %} 
</ol>

 

The above code iterates through seat_arrangement using {% for %} tag. In every iteration, the {% cycle %} tag cycles through ‘row1’ and ‘row2’ to produce a list of sitting arrangements of students.

Output:

<ol>   <li class="row1">Naman</li>   <li class="row2">Nisha</li>   <li class="row1">Rahul</li>   <li class="row2">Snehal</li>   <li class="row1">Joy</li> </ol>

 

Extends :

This tag is used for the inheritance of Django templates. We don’t need to repeat the same code again and again. With extends, we can inherit Django templates as well as Django variables.

Example usage: 

{% extends "./header.html" %}

 

In the above code with the extent tag, we have inherited the header.html template in our new template.

If :

The {% if %} tag in the Django template is the conditional tag, and it works just like it does in Python.

Example Usage:

a= 5
b= 6
c= 5
{% if a == b %}
  <p>a is equal to b</p>
{% elif a == c %}
  <p>a is equal to c</p>
{% else %}
  <p>a is not equal to c and b</p>
{% endif %}

 

The above code checks if a is equal to b or c using Django operators and prints the answer after rendering the template. The output of the following code is:

Output:

a is equal to c

 

For …empty loop :

The {% for %} tag can take an optional {% empty %} clause whose text is displayed if the given array is empty or could not be found:

Example usage: 

seat_arrangement = []

<ol> 
{% for all student in seat_arrangement %}  
    <li class="{% cycle 'row1' 'row2' %}">{{ student }}</li>
{% empty %}
    <li>Sorry, no students in this list.</li>  
{% endfor %} 
</ol>

 

Since the seat_arrangement list is empty, it will display the text under the {% empty %} clause.

Output:

<ol>   <li>Sorry, no students in this list.</li> </ol>

 

Boolean Operators:

The {% if %} tags may use and, not and or operator to test several variables with a given variable:

Example usage: 

{% if student_list and teacher_list %}
    Both students and teachers are available.
{% endif %}

{% if not seat_arrangement %}
    There are no seat arrangement.
{% endif %}

{% if student_list or teacher_list %}
    There are some students or some teachers.
{% endif %}

 

In the above example, we can see the usage of boolean operators with some dummy student and teacher lists. Refer to the official docs to learn more about Boolean Operators.

Include :

We can use include tags in Django templates to load one template in another and render it with the current context. The template name can be a variable or a (quoted) string, in either single or double-quotes.

Example usage: 

{% include "./header.html" %}

 

Generally, the template name is relative to the template’s root directory. A string argument may be a relative path starting with ./ or ../.

Lorem :

The lorem tag provides random "lorem ipsum" Latin text. This is useful for delivering sample texts in templates.

The tag takes three optional arguments:

1. count: The number of items (based on method) to output.
2. method     
   • b – plain-text paragraphs (the default).
   • p – HTML paragraphs.
   • w – words.    
3. random – When included, outputs random Latin words in place of the traditional lorem ipsum text.

Example usage: 

• {% lorem %} will output the standard "lorem ipsum" paragraph.
• {% lorem 2 p %} will output the standard "lorem ipsum" paragraph and two random sections, each wrapped in HTML tags.
• {% lorem 2 w random %} will output two random Latin words.

Frequently Asked Questions

1. What are some other tags in Django templates?
   Some other essential tags in Django are firstof, now, url, load, etc.
    
2. What is the Django Template?
   A Django template is a python string or a text document marked up using the Django template language. It uses its syntax to deal with tags, variables, filters, etc. 

Key Takeaways

In this article, we learned about Tags in Django Template and used some commonly used tags in Django.

Don't stop here. Check out the blogs Best Django Books, Top 30 Basic Django Interview Questions: Part 1, and Top 30 Intermediate Django Interview Questions: Part 2.

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