In a Django template, how to specify a dictionary key which is itself an attribute?

Question

I\'m working on a Django project with a ListView that has both a search form, known in the view\'s context as search_form, and a filter form, fil

Answer 1

I finally solved this by writing a custom get filter as described in Django template how to look up a dictionary value with a variable:

from django import template

register = template.Library()


@register.filter
def get(dictionary, key):
    return dictionary.get(key)

I updated _search.html as follows:

{% load get %}

<form action="{% url action %}" method="get" class="left search col s6 hide-on-small-and-down" novalidate>
  <div class="input-field">
    <input id="search" placeholder="{{ placeholder }}"
        autocomplete="off" type="search" name="q"
        value="{{ search_form.q.value.strip|default:'' }}"
        data-query="{{ search_form.q.value.strip|default:'' }}">
    <label for="search" class="active"><i class="material-icons search-icon">search</i></label>
    <i data-behavior="search-clear"
        class="material-icons search-icon"
        {% if not search_form.q.value %}style="display: none;"{% endif %}>close</i>
  </div>
  {% if filter_form %}
    {% for field in filter_form %}
      <input type="hidden" name="{{ field.name }}" value="{{ request.GET|get:field.name }}"/>
    {% endfor %}
  {% endif %}
</form>

Now, if I try to search a filtered result, it works as expected:

Note that this also works fine for the filters that are not applied - these have the value None instead of an empty string - without any need to filter them out in the form.

Answer 2

So it basically boils down to not submitting keys in the GET request that have an empty string value. This appears to be unsupported natively in HTML; you need some JS magic to make this happen. See this thread: How to prevent submitting the HTML form's input field value if it empty

However, a pure Django solution would be to modify your filter dict to exclude keys that are null. I am not sure how you are filtering this in Django, but assuming you have override the get_queryset method; you can always do:

def get_queryset(self):
    qs = super(YourView, self).get_queryset()
    filters = {k, v for k, v in request.GET.items() if v != ''}  # Be as generic/specific as needed here for exclusion
    qs = qs.filter(**filters)  # Fire your filtering logic here; this is a sample
    return qs