Add class to Django label_tag() output

问题

I need some way to add a class attribute to the output of the label_tag() method for a forms field.

I see that there is the ability to pass in an attrs dictionary and I have tested it in the shell and I can do something like:

for field in form:
    print field.label_tag(attrs{\'class\':\'Foo\'})

I will see the class=\'Foo\' in my output, but I don\'t see a way to add an attrs argument from the template - in fact, templates are designed specifically against that, no?

Is there a way in my form definition to define the class to be displayed in the label?

In the form, I can do the following to give the inputs a class

self.fields[\'some_field\'].widget.attrs[\'class\'] = \'Foo\'

I just need to have it output the class for the as well.

回答1:

A custom template tag seems to be the solution. A custom filter would also do, although it can be less elegant. But you would need to fall back to custom form rendering in both cases.

If this is a task of high importance; I'd create a Mixin that allows me to annotate the form fields with label classes and supplies form rendering methods using those classes. So that the following code works:

{{ form.as_table_with_label_classes }}

But I'd like to ask; Do you really need a class on the label tag? I mean HTML design-wise. It is absolutely necessary to add a class in there? Couldn't it be solved with some CSS like:

encapsulating_selector label {
    some-attr: some-value;
}

I sometimes use jQuery for such cases where; it will improve the page if it works, but it won't be a disaster if it doesn't. And keep the HTML source as lean as possible.

回答2:

Technique 1

I take issue with another answer's assertion that a filter would be "less elegant." As you can see, it's very elegant indeed.

@register.filter(is_safe=True)
def label_with_classes(value, arg):

    return value.label_tag(attrs={'class': arg})

Using this in a template is just as elegant:

{{ form.my_field|label_with_classes:"class1 class2"}}

Technique 2

Alternatively, one of the more interesting technique I've found is: Adding * to required fields.

You create a decorator for BoundField.label_tag that will call it with attrs set appropriately. Then you monkey patch BoundField so that calling BoundField.label_tag calls the decorated function.

from django.forms.forms import BoundField

def add_control_label(f):
    def control_label_tag(self, contents=None, attrs=None):
        if attrs is None: attrs = {}
        attrs['class'] = 'control-label'
        return f(self, contents, attrs) 
    return control_label_tag

BoundField.label_tag = add_control_label(BoundField.label_tag)    

回答3:

How about adding the CSS class to the form field in the forms.py, like:

class MyForm(forms.Form):
    title = forms.CharField(widget=forms.TextInput(attrs={'class': 'foo'}))

then I just do the following in the template:

<label for="id_{{form.title.name}}" class="bar">
    {{ form.title }}
</label>

Of course this can easily be modified to work within a for loop tag in the template.

回答4:

A bit too late but came across a similar problem. Hope this helps you.

class MyForm(forms.ModelForm):

    def __init__(self, *args, **kwargs):
        super(MyForm, self).__init__(*args, **kwargs)
        self.fields['myfield1'].widget.attrs.update(
            {'class': 'form-control'})
        self.fields['myfield2'].widget.attrs.update(
            {'class': 'form-control'})

    def as_two_col_layout(self):

        return self._html_output(
            normal_row='<div class="form-group"><span class="col-xs-2">%(label)s</span> <div class="col-xs-10">%(field)s%(help_text)s</div></div>',
            error_row='%s',
            row_ender='</div>',
            help_text_html=' <span class="helptext">%s</span>',
            errors_on_separate_row=True)

    class Meta:

        model = mymodel
        fields = ['myfield1', 'myfield2']

回答5:

I am agree with answer number one, with css this could be done, but. What is the reson for this to be in django source?

In django.forms.forms.py there's this definition that shows there's code to display attrs in labels:

class BoundField(StrAndUnicode): 
# ....
def label_tag(self, contents=None, attrs=None):
    contents = u'<label for="%s"%s>%s</label>' % (widget.id_for_label(id_), attrs, unicode(contents))

but _html_output calls this function without attrs:

label = bf.label_tag(label) or ''

So it seems that django is partially prepared to this but actually it does not used it.

回答6:

@register.simple_tag
def advanced_label_tag(field):
    """ Return form field label html marked to fill by `*` """
    classes = []
    attrs = {}
    contents = force_unicode(escape(field.label))

    if field.field.required:
        classes.append(u'required')
        contents = force_unicode('%s <span>*</span>'%escape(field.label))

    if classes:
        attrs['class'] = u' '.join(classes)

    return field.label_tag(contents=contents, attrs=attrs)

回答7:

class CustomBoundField(BoundField):
    def label_tag(self, contents=None, attrs=None):
        if self.field.required:
            attrs = {'class': 'required'}
        return super(CustomBoundField, self).label_tag(contents, attrs)

class ImportViewerForm(forms.Form):
    url = fields.URLField(widget=forms.TextInput(attrs={'class': 'vTextField'}))
    type = fields.ChoiceField(choices=[('o', 'Organisation'), ('p', 'Program')], widget=forms.RadioSelect,
                              help_text='Url contain infornation about this type')
    source = fields.ChoiceField(choices=[('h', 'hodex'), ('s', 'studyfinder')], initial='h', widget=forms.RadioSelect)

    def __getitem__(self, name):
        "Returns a BoundField with the given name."
        try:
            field = self.fields[name]
        except KeyError:
            raise KeyError('Key %r not found in Form' % name)
        return CustomBoundField(self, field, name)

class Media:
    css = {'all': [settings.STATIC_URL + 'admin/css/forms.css']}

You need change method label_tag in BoundField class, and use it in form

来源：https://stackoverflow.com/questions/414679/add-class-to-django-label-tag-output