Setting initial Django form field value in the __init__ method

I had that exact same problem and I solved it doing this:

def __init__(self, *args, **kwargs):    instance = kwargs.get('instance', None)    kwargs.update(initial={        # 'field': 'value'        'km_partida': '1020'    })    super(ViagemForm, self).__init__(*args, **kwargs)    # all other stuff

Try this way:

super(ViagemForm, self).__init__(*args, **kwargs)if field_value:    #self.initial[field_name] = field_value    self.fields[field_name].initial = field_value

I want to mention, although this might not solve your problem, that an 'initial' dict kwarg sent to a form appears to get preference over field['field_name'].initial.

class MyView(View):    form = MyForm(initial={'my_field': 'first_value'})class MyForm(Form):    def __init__(self, *args, **kwargs):        super().__init__(*args, **kwargs)        self.fields['my_field'].initial = 'second_value'

my_field rendered will have initial set to 'first_value'.

Some options (among others) might be:

Determine second_value in the view before initializing the form:

class MyView(View):    # determine second_value here    form = MyForm(initial={'my_field': 'second_value'})

replace first_value with second_value in initial before calling super():

class MyForm(Form):    def __init__(self, *args, **kwargs):        # determine second_value here        if kwargs.get('initial', None):            kwargs['initial']['my_field'] = 'second_value'        super().__init__(*args, **kwargs)

Make sure 'first_value' isn't in kwargs['initial'] before calling super():

class MyForm(Form):    def __init__(self, *args, **kwargs):        if kwargs.get('initial', None):            if kwargs['initial']['my_field']                del(kwargs['initial']['my_field']        super().__init__(*args, **kwargs)        # determine second_value here        self.fields['my_field'].initial = 'second_value'