Django template add GET parameter after current URL

Question

Previously, I handled my translation with GET parameter, by requesting the ?lang=<lang_code> on URL.

<h6>{% trans "Translate" %}</h6>
{% get_current_language as LANGUAGE_CODE %}
{% get_available_languages as LANGUAGES %}
{% get_language_info_list for LANGUAGES as languages %}
<span id="language-icons">
  {% for language in languages %}
    {% if language.code == 'id' %}
      <a href="?lang=id" title="Indonesia">
        <img height="20px" src="{% static 'icons/flags/id.svg' %}">
      </a>
    {% elif language.code == 'en' %}
      <a href="?lang=en" title="English">
        <img height="20px" src="{% static 'icons/flags/us.svg' %}">
      </a>
    {% endif %}
  {% endfor %}
</span>

When I handle with {{ request.META.QUERY_STRING }},
and the previous URL already included lang= param (like: /path/to/?page=2&lang=en).
The next lang= will attempts multiple times (like: /path/to/?page=2&lang=en&lang=id).

I want to replace the old lang=en param with new lang=id. So, the url should be /path/to/?page=2&lang=id.

Here is what I was tried;

{% with QUERY_STRING=request.META.QUERY_STRING %}
  {% if QUERY_STRING %}
    {% if 'lang' in QUERY_STRING %}
      <a href="?{{ QUERY_STRING|replace_with:"lang=id" }}">   <!-- something like `replacer` -->
    {% else %}
      <a href="?{{ QUERY_STRING }}?lang=id %}">...</a>
    {% endif %}
  {% else %}
    <a href="?lang=id">...</a>
  {% endif %}
{% endwith %}

I just think, the above problem maybe nice when handle with templatetags, like:

@register.filter
def append_url_param(request, replacer='lang=id'):
    params = request.META.QUERY_STRING        # 'id=1&lang=en'
    replacer_list = replacer.split('=')

    if len(replacer_list) > 1:
        key = replacer_list[0]
        value = replacer_list[-1]

        if key in params:
            params = params.replace(????)

Asked By: binpy

||

Source

Answer 1

Finally, I solved this problem with urllib.parse library:

from urllib import parse


@register.filter
def append_url_param(url, rep='lang=id'):
    """
    function to replace the query string of url.
    :param `url` is string full url or GET query params.
    :param `rep` is string replacer.
    """
    rep_list = rep.split('=')
    queries = url

    if len(rep_list) > 1:
        rep_key = rep_list[0]
        rep_val = rep_list[1]
    
        if 'http' in url:
            queries = parse.urlsplit(url).query

        dict_params = dict(parse.parse_qsl(queries))
        dict_params.update({rep_key: rep_val})

        queries_list = []

        for (k, v) in dict_params.items():
            queries_list.append('%s=%s' % (k, v))

        base_url_list = url.split('?')
        base_url = base_url_list[0]
        
        if len(base_url_list) <= 1:
            base_url = ''
        
        queries_str = '&'.join(queries_list)

        return '%s?%s' % (base_url, queries_str)

    return url

and to use in the template;

<a href="{{ request.META.QUERY_STRING|append_url_param:'lang=id' }}">...</a>

<a href="{{ request.META.QUERY_STRING|append_url_param:'lang=en' }}">...</a>

The result example;

<a href="?page=1&q=abc&lang=id">...</a>

<a href="?id=3&lang=en">...</a>

Console example;

>>> url = 'http://127.0.0.1:8000/add-edit/?id=3&page=1&lang=en'
>>> append_url_param(url=url, rep='lang=id')
'http://127.0.0.1:8000/add-edit/?id=3&page=1&lang=id'
>>>
>>>
>>> url = 'id=3&page=1&lang=id'
>>> append_url_param(url=url, rep='lang=en')
'?id=3&page=1&lang=en'
>>>

Answered By: binpy

Django template add GET parameter after current URL

Question:

Answers: