Form function is always passing as valid

Question

I created a form and a view that checks if a user's input, lesson_instrument and lesson_level, match the user object's values of instrument1 and level1. The form is intended to pass if lesson_instrument == instrument1, and level1 >= lesson_level. However, no matter the input I put in the form, the form always passes as valid, it doesn't fail, even when the function does not meet the requirements. I would greatly appreciate any help in solving this issue as I can't seem to figure out what's wrong.

forms.py

class LessonForm(forms.ModelForm):
    lesson_instrument = forms.ChoiceField(choices=instrument_list, widget=forms.Select(attrs={'class' : 'form-control', 'required' : 'True'}))
    lesson_level = forms.ChoiceField(choices=level_list, widget=forms.Select(attrs={'class' : 'form-control', 'required' : 'True'}))
    lesson_length = forms.ChoiceField(choices=length_list, widget=forms.Select(attrs={'class' : 'form-control', 'required' : 'True'}))
    lesson_day = forms.ChoiceField(choices=day_list, widget=forms.Select(attrs={'class' : 'form-control', 'required' : 'True'}))
    lesson_time = forms.ChoiceField(choices=time_list, widget=forms.Select(attrs={'class' : 'form-control', 'required' : 'True'}))
    lesson_weekly = forms.BooleanField(required=False)

    class Meta:
        model = Lesson
        fields = ('lesson_instrument', 'lesson_level', 'lesson_length', 'lesson_day', 'lesson_time', 'lesson_weekly')

    def lesson_allowed(self):
        # Check that the user is allowed to teach that instrument and level
        lesson_instrument = self.cleaned_data.get("lesson_instrument")
        lesson_level = self.cleaned_data.get("lesson_level")

        if lesson_instrument == user.instrument1:
            level1 = user.level1
            if lesson_level == "Beginner":
                lesson_level = 1
                if level1 == 'Beginner':
                    level1 = 1 
                    if level1  >= lesson_level:
                        return lesson_instrument
                        return lesson_level
                if level1 == 'Advanced':
                    level1 = 2 
                    if level1  >= lesson_level:
                        return lesson_instrument
                        return lesson_level
                if level1 == 'Intermediate':
                    level1 = 3 
                    if level1  >= lesson_level:
                        return lesson_instrument
                        return lesson_level 
            if lesson_level == "Advanced":
                lesson_level = 2
                if level1 == 'Beginner':
                    level1 = 1 
                    if level1  >= lesson_level:
                        return lesson_instrument
                        return lesson_level
                if level1 == 'Advanced':
                    level1 = 2 
                    if level1  >= lesson_level:
                        return lesson_instrument
                        return lesson_level
                if level1 == 'Intermediate':
                    level1 = 3 
                    if level1  >= lesson_level:
                        return lesson_instrument
                        return lesson_level 
            if lesson_level == "Intermediate":
                lesson_level = 3
                if level1 == 'Beginner':
                    level1 = 1 
                    if level1  >= lesson_level:
                        return lesson_instrument
                        return lesson_level
                if level1 == 'Advanced':
                    level1 = 2 
                    if level1  >= lesson_level:
                        return lesson_instrument
                        return lesson_level
                if level1 == 'Intermediate':
                    level1 = 3 
                    if level1  >= lesson_level:
                        return lesson_instrument
                        return lesson_level

views.py

def new_lesson(request):
    if request.method == 'POST':
        form = LessonForm(request.POST)

        if form.is_valid():
            lessons = form.save(commit=False)
            lessons.user = request.user
            lessons.save()
            messages.success(request,'Lesson successfully created')
            return redirect('/teacher/schedule')

        else:
            messages.error(request, 'Information entered was invalid')

    else:
        form = LessonForm()

    lessons = Lesson.objects.filter(user=request.user)
    form = LessonForm(request.POST)
    context = {'form' : form, 'lessons': lessons}
    return render(request, 'teacher/new_lesson.html', context)

Answer 1

For custom validation, you should define a custom clean() method for your form. See this section in the Django docs. It looks like this is what you're attempting to do with your lesson_allowed method, but you should call it clean() and throw forms.ValidationError() if it does not pass.