How to call function within if statement in Django template

Question

I have a custom template tag as following:

@register.simple_tag
def call_method(obj, method_name, *args):
    """
    Usage
    in shell
    obj.votes.exists(user_id)

    in template
    {% call_method obj.votes 'exists' user.id %}
    """
    method = getattr(obj, method_name)
    return method(*args)

Then I can call it in the template (Class-based detail view) as following.

{% call_method object.votes 'exists' user.id %}

My question is how can use this template tag in If statement? For example, why I cannot use like:

{% if call_method object.votes 'exists' user.id %}

I am using django-vote [https://github.com/shanbay/django-vote][1]

My goal is to check whether a user already voted so that I can change the class of the vote button. Otherwise, I can already check it in view. And it works fine.

If it is not possible to use the simple tag with argument within If statement, could you please suggest a way to reach my goal?

Edit: I am adding view.

def vote(request, slug):
    term = Term.objects.get(slug=slug)

    if term.votes.exists(user_id=request.user.id):
        term.votes.down(user_id=request.user.id)
    else:
        term.votes.up(user_id=request.user.id)

    return HttpResponseRedirect(term.get_absolute_url())

and Model:

class Term(VoteModel, models.Model):

Ammad Khalid · Accepted Answer · 2020-01-05 13:36:06Z

1

why not to pass the variable from view to template? for example inside of view context you can set your own context variable, for example:

class MyView(generic.DetailView):

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        obj = self.get_object()
        is_user_voted_already = obj.votes.exists(user_id)
        context.update({
            'is_user_voted_already': is_user_voted_already
        })
        return context

and in template view you can check. Just like this:

{% if is_user_voted_already %}code here if user voted already{%else}code here user not voted already{%endif%}

answered Jan 5, 2020 at 13:36

Ammad Khalid

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1 Comment

sagayev Over a year ago

Ammad, overlooked your answer at first. It works actually. Changed user_id to self.request.user.id. Thank you very much.

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