Renders a form field like a django-crispy-forms field::

        {% load crispy_forms_tags %}
        {{ form.field|as_crispy_field }}

    or::

        {{ form.field|as_crispy_field:"bootstrap" }}

def as_crispy_field(field, template_pack=TEMPLATE_PACK, label_class="", field_class=""):
    """
    Renders a form field like a django-crispy-forms field::

        {% load crispy_forms_tags %}
        {{ form.field|as_crispy_field }}

    or::

        {{ form.field|as_crispy_field:"bootstrap" }}
    """
    if not isinstance(field, forms.BoundField) and settings.DEBUG:
        raise CrispyError('|as_crispy_field got passed an invalid or inexistent field')

    attributes = {
        'field': field,
        'form_show_errors': True,
        'form_show_labels': True,
        'label_class': label_class,
        'field_class': field_class,
    }
    helper = getattr(field.form, 'helper', None)

    template_path = None
    if helper is not None:
        attributes.update(helper.get_attributes(template_pack))
        template_path = helper.field_template
    if not template_path:
        template_path = '%s/field.html' % template_pack
    template = get_template(template_path)

    c = Context(attributes).flatten()
    return template.render(c)