Customize/remove Django select box blank option

Question

I'm using Django 1.0.2. I've written a ModelForm backed by a Model. This model has a ForeignKey where blank=False. When Django generates HTML for this form it creates a select box with one option for each row in the table referenced by the ForeignKey. It also creates an option at the top of the list that has no value and displays as a series of dashes:

<option value="">---------</option>

What I'd like to know is:

1. What is the cleanest way to remove this auto-generated option from the select box?

2. What is the cleanest way to customize it so that it shows as:

   <option value="">Select Item</option>
   

In searching for a solution I came across Django ticket 4653 which gave me the impression that others had the same question and that the default behavior of Django may have been modified. This ticket is over a year old so I was hoping there might be a cleaner way to accomplish these things.

Thanks for any help,

Jeff

Edit: I've configured the ForeignKey field as such:

verb = models.ForeignKey(Verb, blank=False, default=get_default_verb)

This does set the default so that it's no longer the empty/dashes option but unfortunately it doesn't seem to resolve either of my questions. That is, the empty/dashes option still appears in the list.

Answer 1

from the docs

The blank choice will not be included if the model field has blank=False and an explicit default value (the default value will be initially selected instead).

so set the default and you're ok

Answer 2

If all else fails there's always JQuery*.

It's dirty but it works.

(*choose your JS poison)

Edit - I'd like to see some justifications for the downvote - it's arguable that a JS solution is cleaner than the accepted answer and it's certainly quicker to implement. I'd say that this is a reasonable case for 'progressive enhancement'.

Answer 3

Haven't tested this, but based on reading Django's code here and here I believe it should work:

class ThingForm(models.ModelForm):
  class Meta:
    model = Thing

  def __init__(self, *args, **kwargs):
    super(ThingForm, self).__init__(*args, **kwargs)
    self.fields['verb'].empty_label = None

EDIT: This is documented, though you wouldn't necessarily know to look for ModelChoiceField if you're working with an auto-generated ModelForm.

EDIT: As jlpp notes in his answer, this isn't complete - you have to re-assign the choices to the widgets after changing the empty_label attribute. Since that's a bit hacky, the other option that might be easier to understand is just overriding the entire ModelChoiceField:

class ThingForm(models.ModelForm):
  verb = ModelChoiceField(Verb.objects.all(), empty_label=None)

  class Meta:
    model = Thing

Answer 4

With Carl's answer as a guide and after rooting around the Django source for a couple hours I think this is the complete solution:

1. To remove the empty option (extending Carl's example):

   class ThingForm(models.ModelForm):
     class Meta:
       model = Thing
   
   
     def __init__(self, *args, **kwargs):
       super(ThingForm, self).__init__(*args, **kwargs)
       self.fields['verb'].empty_label = None
       # following line needed to refresh widget copy of choice list
       self.fields['verb'].widget.choices =
         self.fields['verb'].choices
   

2. To customize the empty option label is essentially the same:

   class ThingForm(models.ModelForm):
     class Meta:
       model = Thing
   
   
     def __init__(self, *args, **kwargs):
       super(ThingForm, self).__init__(*args, **kwargs)
       self.fields['verb'].empty_label = "Select a Verb"
       # following line needed to refresh widget copy of choice list
       self.fields['verb'].widget.choices =
         self.fields['verb'].choices
   

I think this approach applies to all scenarios where ModelChoiceFields are rendered as HTML but I'm not positive. I found that when these fields are initialized, their choices are passed to the Select widget (see django.forms.fields.ChoiceField._set_choices). Setting the empty_label after initialization does not refresh the Select widget's list of choices. I'm not familiar enough with Django to know if this should be considered a bug.

Answer 5

See here for the complete debate on and methods for resolution of this issue.