Custom template tag for Django to return link tag, if target path is not current, and text if it is

link_unless_current

# Writing custom template tags:
# https://docs.djangoproject.com/en/3.0/howto/custom-template-tags/#writing-custom-template-tags
#
# Usage:
# {% link_unless_current 'target_path_name' 'optional_link_text' %}
# returns
# if not current: <a href="{ reverse(target_path_name) }">{ link_text }</a>
# if current:     <strong>{ link_text }</strong>

from django.template import Library
from django.urls import reverse
from django.utils.html import format_html, mark_safe
import re

register = Library()

@register.simple_tag(takes_context=True)
def link_unless_current(context, target_path_name, link_text=''):
    """
    (Link should not target current page, in terms of UX)
    Returns link tag if target path is not current.
    Highlightes if target is parent of current.
    """
    current_path = context['request'].path
    target_path = reverse(target_path_name)

    if link_text == '':
        link_text = target_path_name.capitalize()

    response = '<a href="{}">{}</a>'

    if current_path == target_path:
        # is current
        response = format_html(
            '<strong>{}</strong>',
            link_text,
        )
    elif re.match(target_path, current_path):
        # is parent of current
        response = format_html(
            response,
            target_path,
            mark_safe(f'<strong>{link_text}</strong>'),
        )
    else:
        # not related to current
        response = format_html(
            response,
            target_path,
            link_text,
        )

    return response