How to Set a Value of Variable Inside Template Code in Django

Django is powerful and popular Python-based web framework that follows the model-template-view (MTV) architecture. While Django encourages separating logic from presentation, there are instances where setting a variable’s value directly within a template becomes necessary. Although its generally recommended to handle such operations within the view or the context processor, there are a few ways to achieve this directly in the template.

Using Django Template Tags

Django provides template tags that enable programmer to perform various operations directly within the template. Heres an overview of how to set a value of a variable inside a template code using Django template tags:

1. Assigning a value to a variable:

To set a value to a variable within a Django template, use the with tag as follows:

{% with variable_name=value %}
    {{ variable_name }}
{% endwith %}

For example, if you want to set variable current_user with the value of the current logged-in user, you can do the following:

{% with current_user=request.user %}
    {{ current_user.username }}
{% endwith %}

2. Conditional assignment:

You can use the if statement to conditionally set the value of a variable in the template. Here’s an example:

{% if condition %}
    {% with variable_name=value1 %}
        {{ variable_name }}
    {% endwith %}
{% else %}
    {% with variable_name=value2 %}
        {{ variable_name }}
    {% endwith %}
{% endif %}

Custom Template Tags or Filters

In more complex scenarios, you might need to create your custom template tags or filters to set the value of a variable. This approach is particularly useful when you need to perform more intricate data manipulation directly within the template.

Creating a custom template tag:

1. Define the custom template tag in a file, say custom_tags.py.
2. Register the custom tag in the Django app.
3. Use the custom tag in the template to set the value of a variable.

Best Practices

While setting a value within a template can provide quick solution, it is generally recommended to keep business logic away from presentation layer. Overuse of such techniques might lead to convoluted templates and make the code harder to maintain.