How to change the rendered field in Django's ModelForm queryset? - django

Question

I want to change the rendered field shown in a model form choicefield, based on some user selected feature, which is language in my case.
I've got a two models. Of the two, the 'Vastausvaihtoehto' model saves an answer in both english and finnish, saving it to the database. It also returns the finnish answer by default, because that's how I've defined the unicode function:
Model
class Vastausvaihtoehto(models.Model):
...
vastaus_fi = models.CharField(
verbose_name=_(u'Vastaus'),
max_length=256,
null=True,
blank=True,
)
vastaus_en = models.CharField(
verbose_name=_(u'Vastaus_en'),
max_length=256,
null=True,
blank=True,
)
...
def __unicode__(self):
return u'%s' % (self.vastaus_fi)
class Valinta(models.Model):
organisaatio = models.ForeignKey(
Organisaatio,
related_name=_(u'valinta'),
null=True,
blank=True,
on_delete=models.CASCADE,
)
kysymys = models.ForeignKey(
Kysymysvaihtoehto,
related_name=_(u'valinta'),
null=True,
blank=True,
)
vastausvaihtoehto = models.ForeignKey(
Vastausvaihtoehto,
related_name=_(u'valinta'),
null=True,
blank=True,
)
def __unicode__(self):
return u'%s' % (self.kysymys)
I also have a ModelForm, that I use to select the correct choices
Form
class ValintaForm(ModelForm):
class Meta:
model = Valinta
fields = '__all__'
widgets = {
'organisaatio':forms.HiddenInput(),
'kysymys':forms.HiddenInput(),
'vastausvaihtoehto':forms.RadioSelect(),
}
And here's my view:
View
class kysymys(View):
template_name = 'mytemplate.html'
success_url = 'something'
def get(self, request, pk, question_id, *args, **kwargs):
kysymys = Kysymysvaihtoehto.objects.get(kysymys_id=int(question_id))
vastausvaihtoehdot = Vastausvaihtoehto.objects.filter(kysymysvaihtoehto=kysymys)
if request.LANGUAGE_CODE == 'fi':
# What do I put here?
else:
# What do I put in here?
form = ValintaForm()
form.fields['vastausvaihtoehto'].queryset = vastausvaihtoehdot
form.fields['vastausvaihtoehto'].empty_label = None
return render(request, self.template_name, {
'form':form,
'kysymys':kysymys,
"pk":pk,
"question_id":question_id,
})
I've tried to query just some certain values using values and values_list, and set them as the ModelForm queryset:
#Like so:
answers_en = Vastausvaihtoehto.objects.filter(kysymysvaihtoehto=kysymys).values_list('pk','vastaus_en')
form.fields['vastausvaihtoehto'].queryset = answers_en
But that does not render the form correctly. Should I add a helper method to the 'Vastausvaihtoehto' model, which returns the english name when called?
I know it's possible to circumvent this by just not using ModelForms, but is there a way to do this while using a ModelForm?

Answer 1

Define your ModelForm with an __init__ method which will accept language and question_id as keyword arguments.
class ValintaForm(ModelForm):
class Meta:
model = Valinta
fields = '__all__'
widgets = {
'organisaatio':forms.HiddenInput(),
'kysymys':forms.HiddenInput(),
'vastausvaihtoehto':forms.RadioSelect(),
}
def __init__(self, *args, **kwargs):
language = kwargs.pop('language', None)
question_id = kwargs.pop('question_id')
super(ValintaForm, self).__init__(*args, **kwargs)
if language == "fi":
kysymys = Kysymysvaihtoehto.objects.get(kysymys_id=int(question_id))
vastausvaihtoehdot = Vastausvaihtoehto.objects.filter(kysymysvaihtoehto=kysymys)
self.fields['vastausvaihtoehto'].queryset = vastausvaihtoehdot
else:
# put your other conditions here
pass
In your views, when you initialize your form, pass the keyword arguments
form = ValintaForm(language=request.LANGUAGE_CODE, question_id=question_id)
Or if you think it is better, you can pass the whole queryset to the forms.
def __init__(self, *args, **kwargs):
qs = kwargs.pop('qs')
super(ValintaForm, self).__init__(*args, **kwargs)
self.fields['vastausvaihtoehto'].queryset = qs
Pass the query set when you initialize form
form = ValintaForm(qs=vastausvaihtoehdot)