How to set title and class in the HTML for the options of a ModelChoiceField?

Question

I have a model

class MyModel(models.Model):
    name = models.CharField(max_length=80, unique=True)
    parent = models.ForeignKey('self', null=True, blank=True)

I want to render a ModelChoiceField for that model that looks like:

<select name="mymodel" id="id_mymodel">
    <option value="1" title="Value 1" class="">Value 1</option>
    <option value="2" title="Value 2" class="Value 1">Value 2</option>
</select>

The differences between this output and the default output for a ModelChoiceField are the title and class elements in the OPTION tag. They don't exist in ModelChoiceField's default output.

For my purposes:

• The title element is supposed to be the Option Name.
• The class element is supposed to be self.parent.name. (this is my problem)

So, in the HTML snippet above, Value 1 has no parent and Value 2 has a parent of Value 1.

What is the best mechanism to change ModelChoiceField's default HTML output?

---

EDIT: I understand how to create a new Widget for rendering HTML. The problem is how to render a value from the underlying model in each of the options.

Answer 1

Look at my example about how to create custom fields in this post

Answer 2

You could make your own widget:

from django.forms.widgets import Select 

class MySelect(Select):

    def __init__(self, attrs=None, choices=(), model):
       self.model = model
       super(Select, self).__init__(attrs)

    def render_options(self, choices, selected_choices):
        def render_option(option_value, option_label):
            option_value = force_unicode(option_value)
            option = self.model.objects.get(pk=option_value)
            selected_html = (option_value in selected_choices) and u' selected="selected"' or ''
            return u'<option value="%s"%s class="%s">%s</option>' % (
                escape(option_value), selected_html,
                str(obj.parent.name),
                conditional_escape(force_unicode(option_label)))
        # Normalize to strings.
        selected_choices = set([force_unicode(v) for v in selected_choices])
        output = []
        for option_value, option_label in chain(self.choices, choices):
            if isinstance(option_label, (list, tuple)):
                output.append(u'<optgroup label="%s">' % escape(force_unicode(option_value)))
                for option in option_label:
                    output.append(render_option(*option))
                output.append(u'</optgroup>')
            else:
                output.append(render_option(option_value, option_label))
        return u'\n'.join(output)

If you also want to chance the field's label: the field class has a method label_from_instance.