Multiple choice form within an advanced search form - django

Question

I am trying to create a multiple choice form where any combination of languages can be chosen. It's within a search form field:
class AdvancedSearchForm(SearchForm):
terms_show_partial_matches = forms.BooleanField(required=False,
label=_("Show partial matches in terms")
)
definitions_show_partial_matches = forms.BooleanField(required=False,
label=_("Show partial matches in definitions")
)
case_sensitive = forms.BooleanField(required=False,
label=_("Case sensitive")
)
...
I would like to implement something like this:
filter_by_part_of_speech = forms.ModelChoiceField(
queryset=PartOfSpeech.objects.all(), required=False,
label=_("Filter by part of speech")
)
However, it needs to be a multiple choice field so that any of the values can be chosen. Ideally though, I'm looking for a form where checkboxes are already checked. So something like this:
LANG_CHOICES = (
("1", "lang1"),
("2", "lang2"),
("3", "lang3"),
("4", "lang4"),
)
filter_by_language = forms.MultipleChoiceField(choices=Language.objects.all().filter(name__in=LANG_CHOICES).values(), required=False, label=_("Filter by language"))
The filter is called from the view with something like this:
tqs = tqs.filter(language=language_filter)
Now although the search works fine, the values are not displayed. On the other hand, they are displayed if I fill up a list and simply write:
choices=list(lang_list)
But then, obviously, the search is not actually performed.
Therefore, my questions are:
Can the constructor be adapted to display the values correctly?
Should I rather implement the filter in the view? If so, how?
Am I using the correct type of form or are there better options, such as providing a list of checkboxes that are checked by default?
I am using Django 2.2 (planning to upgrade soon) for now.
The template file simply refers to the search def in the view, which calls the advanced search form and the others:
{% block breadcrumbs_item %}{% trans "Advanced Search" %}{% endblock %}
Not that relevant I think, but here is the Language model:
class Language(models.Model):
iso_code = models.CharField(primary_key=True, max_length=10, verbose_name=_("ISO code"))
name = models.CharField(max_length=50, verbose_name=_("name"))
description = models.TextField(verbose_name=_("description"), null=True, blank=True)
class Meta:
verbose_name = _("language")
verbose_name_plural = _("languages")
def __str__(self):
return _("%(language_name)s (%(iso_code)s)") % {'language_name': self.name, 'iso_code': self.iso_code}
EDIT: Clarification based on Milo Persic's reply.
The request method in the view for the search functionality (that includes calling AdvancedSearchForm) is GET.
if request.method == 'GET' and 'search_string' in request.GET:
if "advanced" in request.path:
search_form = AdvancedSearchForm(request.GET)
else:
search_form = SearchForm(request.GET)
if search_form.is_valid():
tqs = Translation.objects.all()
dqs = Definition.objects.all()
data = search_form.cleaned_data
...
language_filter = data['filter_by_language']
case_filter = data['case_sensitive']
qs = apply_filters(tqs, dqs, language_filter, case_filter, orig_search_string)
etc.
The search form and results are appended and returned as context to the template:
return render(request, template_name, context)
Within AdvancedSearchForm, variables using ModelChoiceField as well as BooleanField are defined. The ModelChoiceField is the one I'm trying to replace with something more user friendly:
filter_by_language = forms.ModelChoiceField(
queryset=Language.objects.all(), required=False,
label=_("Filter by language")
)
The idea is that the default search result will include all four languages (it won't be more than that) but that any combination of them can be unchecked if so desired. With ModelChoiceField, it seems that only one can be chosen.
I'm still trying to learn if ModelMultipleChoiceField is the correct choice, but this is what I have so far:
filter_by_language = forms.ModelMultipleChoiceField(required=True, queryset=Language.objects.all().filter(name__in=LANG_CHOICES).values(),
widget=forms.CheckboxSelectMultiple)
Nothing next to "filter by language".
Only using the names in LANG_CHOICES instead of the numbers actually result in something but it shows the query set. Narrowing it down using "value_list('name')" shows only the language name but still with the syntax, e.g. "('English',)".
mmcf_qs = Language.objects.all().filter(name__in=LANG_CHOICES).values_list('name')
filter_by_language = forms.ModelMultipleChoiceField(required=True, queryset=mmcf_qs)
I'm trying to figure out how to extract the text but maybe this isn't the right approach.

Answer 1

I would use something like CheckBoxSelectMultiple in the form:
(disclaimer, I do not know if this is supported as written in django 2.2)
filter_by_language = forms.ModelMultipleChoiceField(required=True,
queryset=Language.objects.all().filter(name__in=LANG_CHOICES).values(),
widget=forms.CheckboxSelectMultiple)
And there are plenty of stack posts on how to make the initial values checked, like this one.
Also, if you end up with a long list of check boxes (a likely scenario using this widget), you can style them into columns for better UX, like so:
<style>
.my-language-checkboxes {
column-width: 25%;
column-count: 4;
column-fill: balance;
}
</style>
<div id="my-language-checkboxes">
{{ form.filter_by_language }}
</div>
As for the view, I'll make an assumption that you know how to write a basic view and it's the save method you need. In that case, you'll need something like:
if request.method == 'POST:
if form.is_valid():
form.save_m2m()
This also assumes that you are relating languages back to a parent object via a ManyToManyField, which is a common scenario.