Custom widget not being marked safe - django

Question

I'm creating a custom widget to display a choice field as a row of buttons.
So far, I've copied the code from the Django source for rendering a radio-choice field as my starting point:
#html_safe
#python_2_unicode_compatible
class ButtonInput(SubWidget):
input_type = 'radio'
def __init__(self, name, value, attrs, choice, index):
self.name = name
self.value = value
self.attrs = attrs
self.choice_value = force_text(choice[0])
self.choice_label = force_text(choice[1])
self.index = index
if 'id' in self.attrs:
self.attrs['id'] += "_%d" % self.index
self.value = force_text(self.value)
def __str__(self):
return self.render()
def render(self, name=None, value=None, attrs=None):
if self.id_for_label:
label_for = format_html(' for="{}"', self.id_for_label)
else:
label_for = ''
attrs = dict(self.attrs, **attrs) if attrs else self.attrs
return format_html(
'<label{}>{} {}</label>', label_for, self.tag(attrs), self.choice_label
)
def is_checked(self):
return self.value == self.choice_value
def tag(self, attrs=None):
attrs = attrs or self.attrs
final_attrs = dict(attrs, type=self.input_type, name=self.name, value=self.choice_value)
if self.is_checked():
final_attrs['checked'] = 'checked'
return format_html('<input{} />', flatatt(final_attrs))
#property
def id_for_label(self):
return self.attrs.get('id', '')
class ButtonFieldRenderer(ChoiceFieldRenderer):
choice_input_class = ButtonInput
class ButtonSelect(RendererMixin, Select):
renderer = ButtonFieldRenderer
_empty_value = ''
My issue is that this code renders the correct HTML, but it's not marked safe - the HTML code renders onto the page. Given that this code is essentially copied straight from the Django source code, this is very surprising.
What is missing? How do I make my widget class html-safe?

Answer 1

Changing the strings in the render method for u'' worked for me
def render(self, name=None, value=None, attrs=None):
if self.id_for_label:
label_for = format_html(u' for="{}"', self.id_for_label)
else:
label_for = ''
attrs = dict(self.attrs, **attrs) if attrs else self.attrs
return format_html(
u'<label{}>{} {}</label>', label_for, self.tag(attrs), self.choice_label
)