Django url template with query parameters

I'm trying to pass query parameters via my view into a link, but it escapes me on how to actually achieve this in a good way.

My template is as following:

<a class="link-button" href="{% url 'videos:index' %}?tag={{ tag }}&page={{ next }}">Next</a>

This returns what I want:

http://127.0.0.1:8000/videos/?tag=1&page=2

While this works, it's quite fragile, does not handle None values and there must be a better way of doing this.

I tried to pass this via the urltemplate tag but it did not seem to be what I was looking for since it requires url config changes for path:

{% url 'videos:index' page=next tag=tag %}

Is there an actual way of doing this or a template tag I can use to get the parameters? I tried searching for this but it gave me a lot of old results and more path urls, like: /videos/page-1/tag-1/ which I'm not looking for.

I was hoping to do something like:

<a href="{% url 'videos:index'}?{% params page=next tag=tag %}">Next</a>

Solution

There is no builtin support, but you can add one yourself. You can for example define the following template tag. We can for example construct files in boldface:

app/
    templatetags/
        __init__.py
        urlparams.py

Where in urlparams.py, we define:

from django import template
from urllib.parse import urlencode

register = template.Library()

@register.simple_tag
def urlparams(*_, **kwargs):
    safe_args = {k: v for k, v in kwargs.items() if v is not None}
    if safe_args:
        return '?{}'.format(urlencode(safe_args))
    return ''

In the template, we can then load the template tag and then use it like with:

{% load urlparams %}

<a href="{% url 'videos:index'}{% urlparams page='1' tag='sometag' %}">Next</a>

Note that strictly speaking, the URL parameters can contain the same key multiple times. This is here not possible. So we can not generate all possible URL parameters, but this is usually quite rare, and in my opinion not a good idea in the first place.