BoundField vs iommi
2025-02-15
In Django 5.2 we got a way to easier customize attributes of forms. Adam Johnson posted an example on mastodon, which I’ve slightly abbreviated below:
class WideLabelBoundField(BoundField):
def label_tag(self, contents=None, attrs=None, label_suffix=None):
if attrs is None:
attrs = {}
attrs['class'] = 'wide'
return super().label_tag(contents, attrs, label_suffix)
class NebulaForm(Form):
name = CharField(
bound_field_class=WideLabelBoundField,
)
To set a single CSS class on a single label, you have to create an entire class. Let’s look at the same thing in iommi:
class NebulaForm(Form):
name = Field.text(
label__attrs__class__wide=True,
)
But, you might object, what if you need to run some code to customize it? Like if the example didn’t just set "wide" as the value, but set it to "wide" only for staff?
Not only is this also easy in iommi, I would argue it’s even easier and cleaner than in the BoundField case above:
class NebulaForm(Form):
name = Field.text(
label__attrs__class__wide=lambda user, **_: user.is_staff,
)