Issue with custom template tags in Django?

Question

I think my template tags are being called when I don't want them to be called, but I can't find a fix anywhere. This is what I have in html:

{% load cTemplateTags %}
    {% if n.priority == 1 %}
        {% if not n.read %}

        <li>
            <div class="alert alert-dismissible alert-warning">
                <button type="button" class="close" data-dismiss="alert" onclick="{% set n = True %}">x</button>
                <a href="{{n.url}}" class="alert-link"> {{n.message}}</a>
            </div>
        </li>
        {% endif %}

    {% endif %}

In my template tags:

from django import template
from notifications.models import Notification
register = template.Library()


class SetVarNode(template.Node):

    def __init__(self, var_name, var_value):
        self.var_name = var_name
        self.var_value = var_value

    def render(self, context):
        try:
            value = template.Variable(self.var_value).resolve(context)
        except template.VariableDoesNotExist:
            value = ""


        for n in Notification.objects.all():
            if n.actor == context[self.var_name].actor:
                if n.message == context[self.var_name].message:
                    if n.priority == context[self.var_name].priority:
                        if n.date == context[self.var_name].date:
                            n.read = bool(self.var_value)
                            n.save()


        return u""


@register.tag(name='set')
def set_var(parser, token):
    """
    {% set some_var = '123' %}
    """

    parts = token.split_contents()
    if len(parts) < 4:
        raise template.TemplateSyntaxError("'set' tag must be of the form: {% set <var_name> = <var_value> %}")

    print(token)
    #print(parts[3])
    return SetVarNode(parts[1], parts[3])

Is there anyway to get my onClick in the HTML to only fire when the button is actually clicked? For whatever reason when I reload the page the value is set to True even though I never clicked the button. Please let me know if you guys can think of anything!

Answer 1

Templates are rendered by the server. Which means all the tags get processed on the server and a plain HTML page is then generated which is sent to the browser/client.

In short:

<button onClick="{% set n = True %}">x</button>

will be rendered to the browser/client as:

<button onClick="True">x</button>

---

UPDATE

Since, you're trying to update the value of n.read asynchronously when a button is clicked, you'll need to find a way to communicate to the server to update the value of n.read .

Below is a minimal example of performing an AJAX request to the server using jQuery library.

<button id="myBtn" data-id="{{ n.id }}">x</button>

<!-- JavaScript -->
<!-- Don't forget to include jQuery -->
<script>
$("#myBtn").on('click', function(), {
    var nId = $(this).attr('data-id');
    $.ajax({
        type: 'POST',
        url: '/link/to/the/view/',
        data: {'id': nId}, // this way server will know which object to update
    });
});
</script>

Now, an AJAX request will be made to the server. You'll need to implement a view on the server which takes care of updating and saving the n object.

---

UPDATE 2

You can find a lot more examples on using Django and AJAX (jQuery) by searching StackOverflow. Well, you can start here .