How to change value of variable in django template?

Question

I want to declare a flag variable in django template and the change it if some thing happened. But when I change value of variable by custom tag it is declared a new variable and doesn't change.

for example my template tag and django template is:

template tag:

@register.simple_tag
def update_variable(value):
    return  value

html:

{% with True as flag %}
     <h1>1: {{ flag }}</h1>
     {% for e in events %}
         {% if e.title == '***' %}
             {% update_variable False as flag %}
             <h1>2: {{ flag }}</h1>
         {% endif %}
     {% endfor %}
     <h1>3: {{ flag }}</h1>
{% endwith %}

and result is:

1: True
2: False
3: True

But the end result should be False! How to do this?

how would it be? the last flag is outside loop, so its taking the one you declared with with — Exprator
same as you have done inside loop. use that template tag before the last flag again — Exprator
It's an example... actually I want to check all elements of an array and if there isn't what i want then change the flag to False, so I want to change it inside of for loop. — Majid A
This is almost certainly the wrong approach. You shouldn't be trying to manipulate values in the template; there's a reason there's no way to do that directly. What exactly are you trying to do with this flag? — Daniel Roseman

Majid A Majid A · Accepted Answer · 2019-07-17T12:36:36

I find a solution for it. for check all element of list we can use custom filter an do some thing there:

html:

 //load custom filter
 {% load my_filters %}


 {% if "anything we want"|is_in:events.all %}
    //do some thing...
 {% else %}
    //do some thing...
 {% end if%}

custom filter in my_filter file:

 register = template.Library()

 def is_in(case, list):
     for element in list:
        if element.time_span == case:
            return True
     return False
 register.filter(is_in)

How to change value of variable in django template?

1 Answers