[django] clean field

__init__.py

from clean_field import *

clean_field.py

from django.forms.util import ValidationError

def clean_field(form, field_name):
    """
    Get the cleaned value of a field, without requiring the entire form to be
    valid.
    """
    try:
        return form.fields[field_name].clean(form.data.get(field_name, None))
    except ValidationError:
        return None