Django modelform widget attributes replaced or disregarded - django

Question

I've been scratching my head over this for the last little while. I have been able to change the modelfield's field queryset and widget attributes, well somewhat!
class InvoiceItemForm(ModelForm):
UOM = forms.ChoiceField (choices = site_defaults.UOM)
class meta:
model = InvoiceItem
fields = ['name', 'costcode', 'rate', 'quantity',]
labels = {'name': 'Item', 'rate': 'Cost Per Unit', 'quantity': 'Base Quantity'}
widgets = {'UOM': forms.Select(choices = site_defaults.UOM )}
def __init__(self, current_user, current_project, *args, **kwargs):
''' Rendering custom ModelForm '''
super(InvoiceItemForm, self).__init__(*args, **kwargs)
the_title = None
the_instance = kwargs.get('instance', None)
if the_instance:
the_costcode = the_instance.costcode
if the_costcode:
the_title = the_costcode.title
self.fields['costcode'].queryset = CostCode.objects.filter(project = current_project, item = 0)
self.fields['costcode'].widget = forms.TextInput(attrs={'class': 'site-flex-select-large', 'value': the_title})
When this is rendered, the costcode field takes the right instance. Also, the class is shown as site-flex-select-large, but the title is shown as the instance.id and not the_title which is the instance.title (a text field is displayed with value of 192 instead of the title of the invoice item).
Why is Django ignoring some changes and accepting some other changes to the field?
I'm not sure if it is a relevant detail or not, but the modelform is used in an inlineformset:
expenses_forms = self.InvoiceItem_InlineFormSet(instance = the_invoice, prefix='expenses', form_kwargs={'current_user': user, 'current_project': project})

Answer 1

A fields widget is not the place that you should be setting initial values for fields. You should set this in the "initial" kwarg to the form's __init__ method, you can pass it to the call to super. You then can set the costcode widget in the Meta
class InvoiceItemForm(ModelForm):
UOM = forms.ChoiceField (choices = site_defaults.UOM)
class Meta:
model = InvoiceItem
fields = ['name', 'costcode', 'rate', 'quantity',]
labels = {'name': 'Item', 'rate': 'Cost Per Unit', 'quantity': 'Base Quantity'}
widgets = {
'UOM': forms.Select(choices = site_defaults.UOM ),
'costcode': forms.TextInput(attrs={'class': 'site-flex-select-large'})
}
def __init__(self, current_user, current_project, *args, **kwargs):
the_instance = kwargs.get('instance', None)
if the_instance:
the_costcode = the_instance.costcode
if the_costcode:
initial = kwargs.get('initial', {})
initial['costcode'] = the_costcode.title
kwargs['initial'] = initial
super(InvoiceItemForm, self).__init__(*args, **kwargs)
EDIT: like Willem says, the costcode field is a TextInput so it does not make sense to set a queryset attribute on it unless you change it to a select

Answer 2

The value is not taken from the attrs, it is taken from the value of that field. You can set the .initial attribute of the field, like:
def __init__(self, current_user, current_project, *args, **kwargs):
''' Rendering custom ModelForm '''
super(InvoiceItemForm, self).__init__(*args, **kwargs)
the_title = None
the_instance = kwargs.get('instance', None)
if the_instance:
the_costcode = the_instance.costcode
if the_costcode:
the_title = the_costcode.title
self.fields['costcode'].queryset = CostCode.objects.filter(project=current_project, item=0)
self.fields['costcode'].initial = the_title
self.fields['costcode'].widget = forms.TextInput(attrs={'class': 'site-flex-select-large'})
That being said, by using a TextInput, it will, as far as I know, just ignore the queryset, and it will not properly validate the data. I think you better use a Select widget [Django-doc] here, and then use some CSS/JavaScript to make it searchable through text.