Django: Forms Queryset

Question

I wonder if that is the right approach. I first call queryset=Reward.objects.all() just to change it right after and filter it. However, I couldn't come up with a better solution. Do you have any thoughts on that?

   class ClaimRewardForm(forms.ModelForm):
        note = forms.CharField(widget=forms.Textarea)
        title = forms.ModelChoiceField(queryset=Reward.objects.all())
        # note = forms.DropDown()

        class Meta:
            model = Reward
            fields = ['title']

        def __init__(self, *args, **kwargs):
            super().__init__(*args, **kwargs)
            self.fields['title'].queryset = Reward.objects.filter(event=self.initial['event'])

Answer 1

If you should process set of models, try change your approach to FormSets https://docs.djangoproject.com/en/2.0/topics/forms/formsets/

Briefly, FormSets approach seem so: 1. Declare ClaimRewardForm class for single model (Reward in your case) 2. Declare ClaimRewardFormSet for ClaimRewardForm with overriding

class BaseClaimRewardFormSet(BaseModelFormSet):

    """By default, when you create a formset from a model, the formset
    will use a queryset that includes all objects in the model"""

    def __init__(self, *args, **kwargs):
        if 'event' in kwargs.keys():
            event = kwargs.pop('event')
        else:
            event = None
        super().__init__(*args, **kwargs)
        if event is not None:
            self.queryset = Reward.objects.filter(event=event)
        else:
            self.queryset = Reward.objects.none()


ClaimRewardFormSet = forms.modelformset_factory(Reward, RewardForm, 
formset=BaseClaimRewardFormSet) 

Answer 2

That queryset is never evaluated, because you always replace it on instantiation, so it doesn't really matter what you put there.

One alternative night be to use Reward.objects.none() to indicate that it's never used.