A Django template is a text document or a Python string marked-up using the Django template language. Django being a powerful Batteries included framework provides convenience to rendering data in a template. Django templates not only allow passing data from view to template, but also provides some limited features of a programming such as variables, for loops, comments, extends, if else etc.
This article revolves about how to use if tag in Templates. The {% if %} tag evaluates a variable, and if that variable is “true” (i.e. exists, is not empty, and is not a false boolean value) the contents of the block are output.
Syntax:
{% if variable %}
// statements
{% else %}
// statements
{% endif %}
Example:
html
{% if athlete_list %} Number of athletes: {{ athlete_list|length }}{% elif athlete_in_locker_room_list %} Athletes should be out of the locker room soon!{% else %} No athletes.{% endif %} |
In the above, if athlete_list is not empty, the number of athletes will be displayed by the {{ athlete_list|length }} variable.
As one can see, the 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.
if – Django template Tags Explanation
Illustration of How to use if tag in Django templates using an Example. Consider a project named neveropen having an app named Lazyroar.
Refer to the following articles to check how to create a project and an app in Django.
Now create a view through which we will pass the context dictionary,
In Lazyroar/views.py,
Python3
# import Http Response from djangofrom django.shortcuts import render # create a functiondef Lazyroar_view(request): # create a dictionary context = { "data" : 99, } # return response return render(request, "Lazyroar.html", context) |
Create a url path to map to this view. In Lazyroar/urls.py,
Python3
from django.urls import path# importing views from views.pyfrom .views import Lazyroar_viewurlpatterns = [ path('', Lazyroar_view),] |
Create a template in templates/Lazyroar.html,
html
{% if data %}Value in data is : - {{ data }}{% else %}Data is empty{% endif%} |
Let’s check what is displayed on “/” are displayed in the template.
{% else %}
Let’s check if {% else %} statement is working or not.
Now let’s pass an empty array and use empty tag along with for tag.
In Lazyroar/views.py,
Python3
## import Http Response from djangofrom django.shortcuts import render # create a functiondef Lazyroar_view(request): # create a dictionary context = { "data" : False, } # return response return render(request, "Lazyroar.html", context) |
Now, check http://127.0.0.1:8000/,
Advanced Usage
if tags may use and, or not to test a number of variables or to negate a given variable:
{% 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 %}
