You cannot put a templatetag into another. Your for-loop is a templatetag that expects the name of an element in your context to iterate over.
If you want to handle the navigation in a template tag you should consider using inclusion tags.
Inclusion tags are functions that use templates to render their data.
A very basic implementation could look something like this:
tags.py
@register.inclusion_tag('navigation.html')
def navigation(selected_id=None):
return {
'navigation': Division.objects.all(),
'selected':selected_id,
}
In your templatetag file you create a dictionary with the navigation items and optionally the currentl selected item to highlight this navigation element.
navigation.html
<ul>
{% for item in navigation %}
<li{% if item.id == selected %} class="selected"{% endif %}>
<a href="{{ item.get_absolute_url }}">{{ item.DivisionValue }}</a>
</li>
{% endfor %}
</ul>
the navigation.html uses the dictionary from the python function as context so you start with simply iterating over the navigation.
base.html
{% navigation %}
or
{% navigation current_division.id %}
In the base.html you call the inclusion tag like a normal template tag. if you want to highlight the current item you add its id as a argument.