Boolean Operators - Django Template Tags

Django provides the ability to use conditional logic like if, else, and elif using Boolean operators within templates. This allows you to conditionally render parts of a webpage based on values passed from your views.

Syntax:

{% if variable boolean_operator value %}
// statements
{% endif %}

We can also use multiple operators such as and, or, and not to build more complex conditions.

For Example:

{% if athlete_list and coach_list %}
    Both athletes and coaches are available.
{% endif %}

{% if not athlete_list %}
    There are no athletes.
{% endif %}

{% if athlete_list or coach_list %}
    There are some athletes or some coaches.
{% endif %}

{% if not athlete_list or coach_list %}
    There are no athletes or there are some coaches.
{% endif %}

{% if athlete_list and not coach_list %}
    There are some athletes and absolutely no coaches.
{% endif %}

Notice that if tag may take one or several {% elif %} clauses, as well as an {% else %} clause that will be displayed if all previous conditions fail. These clauses are optional.

Example of Boolean Operators in Django

Let’s look at a working example using a Django project geeksforgeeks with an app named geeks.

Refer to the following articles to check how to create a project and an app in Django.  

• How to Create a Basic Project using MVT in Django?
• How to Create an App in Django ?

After setting up the project and app folder, follow these steps:

1. views.py

Create a view through which we will pass the context dictionary in geeks/views.py: 

from django.shortcuts import render

def geeks_view(request):
    context = {
        "data": 99,
    }
    return render(request, "geeks.html", context)

2. urls.py

Create a url path to map to this view in geeks/urls.py,

from django.urls import path
from .views import geeks_view

urlpatterns = [
    path('', geeks_view),
]

3. templates/geeks.html

Create a geeks.html file in templates folder of the app (geeks) if the folder already exists, if not then create the templates folder and then the geeks.html file in it:

{% if data == 99 %}
    Value in data is: {{ data }}
{% else %}
    Data is empty
{% endif %}

Run the app using command- python manage.py runserver and visit http://127.0.0.1:8000/ to see the output.

Common Boolean Operators in Django Templates

== (Equal to)

Returns True if values on both side of the operator are equal.

{% if somevar == "x" %}
somevar is equal to "x"
{% endif %}

!= (Not equal to)

Returns True if the values are not equal.

{% if somevar != "x" %}
somevar is not equal to "x"
{% endif %}

< (Less than)

Checks if the left value is less than the right value.

{% if somevar < 100 %}
somevar is less than 100
{% endif %}

> (Greater than)

Checks if the left value is greater than the right value.

{% if somevar > 0 %}
somevar is greater than 0
{% endif %}

<= (Less than or equal to)

Checks if the left value is less than or equal to the right value.

{% if somevar <= 100 %}
somevar is less than or equal to 100
{% endif %}

>= (Greater than or equal to)

Checks if the left value is greater than or equal to the right value.

{% if somevar >= 1 %}
somevar is greater than or equal to 1
{% endif %}

in (Contained within)

Tests if a value exists in a list, string, or QuerySet.

{% if "bc" in "abcdef" %}
  "bc" is found in "abcdef"
{% endif %}

{% if "hello" in greetings %}
  "hello" is in the greetings list or set
{% endif %}

{% if user in users %}
  user is present in the users QuerySet
{% endif %}

not in (Not contained within)

It's the negation (opposite) of the in operator.

{% if "z" not in "abc" %}
  "z" is not found in "abc"
{% endif %}

is (Object identity)

Tests if two values are the same object.

{% if somevar is True %}
  This appears if and only if somevar is True.
{% endif %}

{% if somevar is None %}
  This appears if somevar is None, or if somevar is not found in the context.
{% endif %}

is not (Negated object identity)

Tests if two values are not the same object.

{% if somevar is not True %}
  somevar is not exactly True
{% endif %}

{% if somevar is not None %}
  somevar is not None
{% endif %}

and, or, not (Logical operators)

• and: All conditions must be True
• or: At least one condition must be True
• not: Reverses the boolean value

{% if user.is_active and user.is_staff %}
  User is active and is a staff member
{% endif %}

{% if user.is_superuser or user.is_staff %}
  User is either a superuser or staff
{% endif %}

{% if not user.is_authenticated %}
  User is not logged in
{% endif %}