Django Form field initial value on failed validation

Question

how do I set the value of a field element after a form has been submitted but has failed validation? e.g.

if form.is_valid():
    form.save()
else:
    form.dat         


        

Answer 1

You can put it in the form class like this:

class MyForm(forms.Form):

    MY_VALUE = 'SOMETHING'
    myfield = forms.CharField(
        initial=MY_VALUE,
        widget=forms.TextInput(attrs={'disabled': 'disabled'})

    def __init__(self, *args, **kwargs):

        # If the form has been submitted, populate the disabled field
        if 'data' in kwargs:
            data = kwargs['data'].copy()
            self.prefix = kwargs.get('prefix')
            data[self.add_prefix('myfield')] = MY_VALUE
            kwargs['data'] = data

        super(MyForm, self).__init__(*args, **kwargs) 

The way it works, is it tests to see if any data has been passed in to the form constructor. If it has, it copies it (the uncopied data is immutable) and then puts the initial value in before continuing to instantiate the form.