CODEWITHSUNDEEP
pythondjangodjango-forms
xdna
xdna

Reputation: 43

Django form: Cleaned data in if statement

I'm new to both python and django and now I've been struggling with this form for a while. What I got is a form with three fields. I want it to be possible to leave each of these fields blank and in the view I'm trying to make an if-elif-else statement depending on what fields that are left blank. It is here it goes wrong though.

If I leave field1 blank a is an empty list if i print it but in the if statement a == [ ] doesn't seem to count. It jumps direcltly to the else part where an error occurs at the random function since it can't be used on d (which is an empty list since it has been filtered with a).

Everything works fine if I don't leave any field in the form blank.

My questions: Is it not possible to do if statements on the cleaned data or am I just doing it all wrong? Why doesn't "if a == [ ]" count?

Here is how parts of the code looks. The view:

def SomeFunction(request):
  if request.method == 'POST':
    form = SomeForm(request.POST)
    if form.is_valid():
        a = form.cleaned_data['field1']
        b = form.cleaned_data['field2']
        c = form.cleaned_data['field3']

        form = form.save()

        if a == []:
            d = Model2.objects.filter(Model2field2=b, Model2field3=c).distinct()
            e = random.choice(d)
            return render(request, 'SomePage.html', {
                'e' : e
            })

        #Here I have some similar elif statements..

        else:
            d = Model2.objects.filter(Model2field1=a, Model2field2=b, Model2field3=c).distinct()
            e = random.choice(d)
            return render(request, 'SomePage.html', {
                'e' : e
            })

The form:

class SomeForm(forms.ModelForm):
  class Meta:
    model = Model1
    fields = ['field1', 'field2', 'field3']
    widgets = {
        'field1' : forms.CheckboxSelectMultiple,
        'field2' : forms.CheckboxSelectMultiple,
        'field3' : forms.CheckboxSelectMultiple,
    }

Upvotes: 2

Views: 834

Answers (2)

Daniel Roseman
Daniel Roseman

Reputation: 599788

You're checking if a is, specifically, an empty list. But that will never be true: the empty value for a ModelMultipleChoiceField (which is the field that is created for a ManyToManyField) is an empty queryset - see the documentation.

Instead, just use a boolean comparison:

if not a:

Upvotes: 1

Lara
Lara

Reputation: 2236

You can do it:

if a is None:
    ....

Upvotes: 1

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