Is django can modify variable value in template?

Question

I want to write template that render somethings only one time.

My ideas is create flag variable for check it is first time or not ?

My code

{% with "true" as data %}
    {% if data == "true" %}
        //do somethings
        ** set data to "false" **
    {% else %}
        //do somethings
    {% endif %}
{% endwith %}

I don't know How to change variable in django template ? (Is it possible ?)

Or

Better way for do this.

Thank you

Answer 1

This can be done with a Django custom filter

django custom filter

def update_variable(value):
    data = value
    return data

register.filter('update_variable', update_variable)

{% with "true" as data %}
    {% if data == "true" %}
        //do somethings
        {{update_variable|value_that_you_want}}
    {% else %}
        //do somethings
    {% endif %}
{% endwith %}

Answer 2

NIKHIL RANE's answer doesn't work for me. Custom simple_tag() can be used to do the job:

@register.simple_tag
def update_variable(value):
    """Allows to update existing variable in template"""
    return value

and then use it like this:

{% with True as flag %}
    {% if flag %}
        //do somethings
        {% update_variable False as flag %}
    {% else %}
        //do somethings
    {% endif %}
{% endwith %}