  
      def __init__(self):
          assert django_filters, 'Using DjangoFilterBackend, but django-filter is not installed'
  
      def get_filter_class(self, view, queryset=None):
          """
          Return the django-filters `FilterSet` used to filter the queryset.
          """
          filter_class = getattr(view, 'filter_class', None)
          filter_fields = getattr(view, 'filter_fields', None)
  
          if filter_class:
              filter_model = filter_class.Meta.model
  
              assert issubclass(queryset.model, filter_model), \
                  'FilterSet model %s does not match queryset model %s' % \
                  (filter_model, queryset.model)
  
              return filter_class
  
          if filter_fields:
              class AutoFilterSet(self.default_filter_set):
                  class Meta:
                      model = queryset.model
                      fields = filter_fields
  
              return AutoFilterSet
  
          return None
  
 
</s> remove         return None

    def filter_queryset(self, request, queryset, view):
        filter_class = self.get_filter_class(view, queryset)

        if filter_class:
            return filter_class(request.query_params, queryset=queryset).qs

        return queryset

    def to_html(self, request, queryset, view):
        filter_class = self.get_filter_class(view, queryset)
        if not filter_class:
            return None
        filter_instance = filter_class(request.query_params, queryset=queryset)
        context = {
            'filter': filter_instance
        }
        template = loader.get_template(self.template)
        return template_render(template, context)

    def get_schema_fields(self, view):
        assert coreapi is not None, 'coreapi must be installed to use `get_schema_fields()`'
        filter_class = getattr(view, 'filter_class', None)
        if filter_class:
            return [
                coreapi.Field(name=field_name, required=False, location='query')
                for field_name in filter_class().filters.keys()
            ]

        filter_fields = getattr(view, 'filter_fields', None)
        if filter_fields:
            return [
                coreapi.Field(name=field_name, required=False, location='query')
                for field_name in filter_fields
            ]

        return []
 </s> add         return DjangoFilterBackend(*args, **kwargs) </s> remove             return AutoFilterSet
 </s> add         from django_filters.rest_framework import DjangoFilterBackend </s> remove     default_filter_set = FilterSet
    template = filter_template

    def __init__(self):
 </s> add     def __new__(cls, *args, **kwargs): </s> remove if 'crispy_forms' in settings.INSTALLED_APPS and crispy_forms and django_filters:
    # If django-crispy-forms is installed, use it to get a bootstrap3 rendering
    # of the DjangoFilterBackend controls when displayed as HTML.
    from crispy_forms.helper import FormHelper
    from crispy_forms.layout import Layout, Submit

    class FilterSet(django_filters.FilterSet):
        def __init__(self, *args, **kwargs):
            super(FilterSet, self).__init__(*args, **kwargs)
            for field in self.form.fields.values():
                field.help_text = None

            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

    filter_template = 'rest_framework/filters/django_filter_crispyforms.html'

elif django_filters:
    # If django-crispy-forms is not installed, use the standard
    # 'form.as_p' rendering when DjangoFilterBackend is displayed as HTML.
    class FilterSet(django_filters.FilterSet):
        def __init__(self, *args, **kwargs):
            super(FilterSet, self).__init__(*args, **kwargs)
            for field in self.form.fields.values():
                field.help_text = None

    filter_template = 'rest_framework/filters/django_filter.html'

else:
    FilterSet = None
    filter_template = None

 </s> add 
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
  
      def __init__(self):
          assert django_filters, 'Using DjangoFilterBackend, but django-filter is not installed'
  
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
        warnings.warn(
            "The built in 'rest_framework.filters.DjangoFilterBackend' is pending deprecation. "
            "You should use 'django_filters.rest_framework.DjangoFilterBackend' instead.",
            PendingDeprecationWarning
        )
  
              return AutoFilterSet
  
          return None
  
keep keep keep keep replace replace replace replace replace replace replace replace replace replace replace replace replace replace replace replace replace replace replace replace replace keep keep keep keep keep
 Deprecate DjangoFilter backend (#4593)

Deprecate the built-in `rest_framework.filters.DjangoFilterBackend` in favour of the third-party `django_filters.rest_framework.DjangoFilterBackend`. 
rest_framework/filters.py