Django Design Patterns and Best Practices: Industry-standard web development techniques and solutions using Python, 2nd Edition

by Arun Ravindran

class PersonDetailsForm(forms.Form): name = forms.CharField(max_length=100) age = forms.IntegerField() def __init__(self, *args, **kwargs): upgrade = kwargs.pop("upgrade", False) super().__init__(*args, **kwargs) # Show first class option? if upgrade: self.fields["first_class"] = forms.BooleanField( label="Fly First Class?") Now, we just need to pass the PersonDetailsForm(upgrade=True) keyword argument to make an additional Boolean input field (a checkbox) appear. A newly introduced keyword argument has to be removed or popped before we call super to avoid the unexpected keyword error. If we use a FormView class for this example, then we need to pass the keyword argument by overriding the get_form_kwargs method of the View class, as shown in the following code: class PersonDetailsEdit(generic.FormView): ... def get_form_kwargs(self): kwargs = super().get_form_kwargs() kwargs["upgrade"] = True return kwargs

Create and use dynamic forms