old_contents: 
  from __future__ import absolute_import
  from copy import deepcopy
  
  from django.db import models
  from django import forms
  from django.utils.translation import ugettext_lazy as _
  
  from django_filters import filterset
  from .filters import BooleanFilter, IsoDateTimeFilter
  from .. import compat, utils
  
  
  FILTER_FOR_DBFIELD_DEFAULTS = deepcopy(filterset.FILTER_FOR_DBFIELD_DEFAULTS)
  FILTER_FOR_DBFIELD_DEFAULTS.update({
      models.DateTimeField: {'filter_class': IsoDateTimeFilter},
      models.BooleanField: {'filter_class': BooleanFilter},
  })
  
  
  class FilterSet(filterset.FilterSet):
      FILTER_DEFAULTS = FILTER_FOR_DBFIELD_DEFAULTS
  
      def __init__(self, *args, **kwargs):
          super(FilterSet, self).__init__(*args, **kwargs)
  
          if compat.is_crispy():
              from crispy_forms.helper import FormHelper
              from crispy_forms.layout import Layout, Submit
  
              layout_components = list(self.form.fields.keys()) + [
                  Submit('', _('Submit'), css_class='btn-default'),
              ]
              helper = FormHelper()
              helper.form_method = 'GET'
              helper.template_pack = 'bootstrap3'
              helper.layout = Layout(*layout_components)
  
              self.form.helper = helper
  
      @property
      def qs(self):
          from rest_framework.exceptions import ValidationError
  
          try:
              return super(FilterSet, self).qs
          except forms.ValidationError as e:
              raise ValidationError(utils.raw_validation(e))
  
new_contents: 
  from __future__ import absolute_import
  from copy import deepcopy
  
  from django.db import models
  from django import forms
  from django.utils.translation import ugettext_lazy as _
  
  from django_filters import filterset
  from .filters import BooleanFilter, IsoDateTimeFilter
  from .. import compat, utils
  
  
  FILTER_FOR_DBFIELD_DEFAULTS = deepcopy(filterset.FILTER_FOR_DBFIELD_DEFAULTS)
  FILTER_FOR_DBFIELD_DEFAULTS.update({
      models.DateTimeField: {'filter_class': IsoDateTimeFilter},
      models.BooleanField: {'filter_class': BooleanFilter},
  })
  
  
  class FilterSet(filterset.FilterSet):
      FILTER_DEFAULTS = FILTER_FOR_DBFIELD_DEFAULTS
  
      @property
      def form(self):
          form = super(FilterSet, self).form
  
          if compat.is_crispy():
              from crispy_forms.helper import FormHelper
              from crispy_forms.layout import Layout, Submit
  
              layout_components = list(form.fields.keys()) + [
                  Submit('', _('Submit'), css_class='btn-default'),
              ]
              helper = FormHelper()
              helper.form_method = 'GET'
              helper.template_pack = 'bootstrap3'
              helper.layout = Layout(*layout_components)
  
              form.helper = helper
  
          return form
  
      @property
      def qs(self):
          from rest_framework.exceptions import ValidationError
  
          try:
              return super(FilterSet, self).qs
          except forms.ValidationError as e:
              raise ValidationError(utils.raw_validation(e))
  
subject: Move crispy helper to '.form' property