so far so good

all tests pass

rest_framework/compat.py

@@ -140,7 +140,7 @@ if markdown is not None and pygments is not None:
                 code = m.group(2).replace('\t', '    ')
                 code = pygments.highlight(code, lexer, self.formatter)
                 code = code.replace('\n\n', '\n&nbsp;\n').replace('\n', '<br />').replace('\\@', '@')
-                return '\n\n%s\n\n' % code
+                return f'\n\n{code}\n\n'
             ret = self.pattern.sub(repl, "\n".join(lines))
             return ret.split("\n")
 

rest_framework/decorators.py

@@ -41,7 +41,7 @@ def api_view(http_method_names=None):
 
         # api_view applied with eg. string instead of list of strings
         assert isinstance(http_method_names, (list, tuple)), \
-            '@api_view expected a list of strings, received %s' % type(http_method_names).__name__
+            f'@api_view expected a list of strings, received {type(http_method_names).__name__}'
 
         allowed_methods = set(http_method_names) | {'options'}
         WrappedAPIView.http_method_names = [method.lower() for method in allowed_methods]
@@ -199,7 +199,7 @@ class MethodMapper(dict):
 
     def _map(self, method, func):
         assert method not in self, (
-            "Method '%s' has already been mapped to '.%s'." % (method, self[method]))
+            f"Method '{method}' has already been mapped to '.{self[method]}'.")
         assert func.__name__ != self.action.__name__, (
             "Method mapping does not behave like the property decorator. You "
             "cannot use the same method name for each mapping declaration.")

rest_framework/exceptions.py

@@ -84,10 +84,8 @@ class ErrorDetail(str):
         return not self.__eq__(other)
 
     def __repr__(self):
-        return 'ErrorDetail(string=%r, code=%r)' % (
-            str(self),
-            self.code,
-        )
+        return f"ErrorDetail(string='{str(self)}', code='{self.code}')"
+
 
     def __hash__(self):
         return hash(str(self))

rest_framework/fields.py

@@ -280,7 +280,7 @@ class CreateOnlyDefault:
         return self.default
 
     def __repr__(self):
-        return '%s(%s)' % (self.__class__.__name__, repr(self.default))
+        return f'{self.__class__.__name__}({repr(self.default)})'
 
 
 class CurrentUserDefault:
@@ -290,7 +290,7 @@ class CurrentUserDefault:
         return serializer_field.context['request'].user
 
     def __repr__(self):
-        return '%s()' % self.__class__.__name__
+        return f'{self.__class__.__name__}()'
 
 
 class SkipField(Exception):

rest_framework/filters.py

@@ -294,8 +294,8 @@ class OrderingFilter(BaseFilterBackend):
             'param': self.ordering_param,
         }
         for key, label in self.get_valid_fields(queryset, view, context):
-            options.append((key, '%s - %s' % (label, _('ascending'))))
-            options.append(('-' + key, '%s - %s' % (label, _('descending'))))
+            options.append((key, f'{label} - {_("ascending")}'))
+            options.append(('-' + key, f'{label} - {_("descending")}'))
             context['options'] = options
         return context
 

rest_framework/generics.py

@@ -61,9 +61,9 @@ class GenericAPIView(views.APIView):
         (Eg. return a list of items that is specific to the user)
         """
         assert self.queryset is not None, (
-            "'%s' should either include a `queryset` attribute, "
-            "or override the `get_queryset()` method."
-            % self.__class__.__name__
+            f"'{self.__class__.__name__}' should either include a `queryset` attribute, "
+            f"or override the `get_queryset()` method."
+
         )
 
         queryset = self.queryset
@@ -120,9 +120,8 @@ class GenericAPIView(views.APIView):
         (Eg. admins get full serialization, others get basic serialization)
         """
         assert self.serializer_class is not None, (
-            "'%s' should either include a `serializer_class` attribute, "
+            f"'{self.__class__.__name__}' should either include a `serializer_class` attribute, "
             "or override the `get_serializer_class()` method."
-            % self.__class__.__name__
         )
 
         return self.serializer_class

rest_framework/parsers.py

@@ -64,7 +64,7 @@ class JSONParser(BaseParser):
             parse_constant = json.strict_constant if self.strict else None
             return json.load(decoded_stream, parse_constant=parse_constant)
         except ValueError as exc:
-            raise ParseError('JSON parse error - %s' % str(exc))
+            raise ParseError(f'JSON parse error - {str(exc)}')
 
 
 class FormParser(BaseParser):
@@ -109,7 +109,7 @@ class MultiPartParser(BaseParser):
             data, files = parser.parse()
             return DataAndFiles(data, files)
         except MultiPartParserError as exc:
-            raise ParseError('Multipart form parse error - %s' % str(exc))
+            raise ParseError(f'Multipart form parse error - {str(exc)}')
 
 
 class FileUploadParser(BaseParser):

rest_framework/relations.py

@@ -46,6 +46,7 @@ class Hyperlink(str):
     We use this for hyperlinked URLs that may render as a named link
     in some contexts, or render as a plain URL in others.
     """
+
     def __new__(cls, url, obj):
         ret = super().__new__(cls, url)
         ret.obj = obj
@@ -70,11 +71,12 @@ class PKOnlyObject:
     instance, but still want to return an object with a .pk attribute,
     in order to keep the same interface as a regular model instance.
     """
+
     def __init__(self, pk):
         self.pk = pk
 
     def __str__(self):
-        return "%s" % self.pk
+        return f"{self.pk}"
 
 
 # We assume that 'validators' are intended for the child serializer,
@@ -376,9 +378,9 @@ class HyperlinkedRelatedField(RelatedField):
 
     def to_representation(self, value):
         assert 'request' in self.context, (
-            "`%s` requires the request in the serializer"
+            f"`{self.__class__.__name__}` requires the request in the serializer"
             " context. Add `context={'request': request}` when instantiating "
-            "the serializer." % self.__class__.__name__
+            "the serializer."
         )
 
         request = self.context['request']

rest_framework/renderers.py

@@ -197,7 +197,7 @@ class TemplateHTMLRenderer(BaseRenderer):
             return self.resolve_template(template_names)
         except Exception:
             # Fall back to using eg '404 Not Found'
-            body = '%d %s' % (response.status_code, response.status_text.title())
+            body = f'{response.status_code} {response.status_text.title()}'
             template = engines['django'].from_string(body)
             return template
 
@@ -414,9 +414,9 @@ class BrowsableAPIRenderer(BaseRenderer):
 
         render_style = getattr(renderer, 'render_style', 'text')
         assert render_style in ['text', 'binary'], 'Expected .render_style ' \
-            '"text" or "binary", but got "%s"' % render_style
+            f'"text" or "binary", but got "{render_style}"'
         if render_style == 'binary':
-            return '[%d bytes of binary content]' % len(content)
+            return f'[{len(content)} bytes of binary content]'
 
         return content.decode('utf-8') if isinstance(content, bytes) else content
 
@@ -660,9 +660,9 @@ class BrowsableAPIRenderer(BaseRenderer):
         response_headers = OrderedDict(sorted(response.items()))
         renderer_content_type = ''
         if renderer:
-            renderer_content_type = '%s' % renderer.media_type
+            renderer_content_type = f'{renderer.media_type}'
             if renderer.charset:
-                renderer_content_type += ' ;%s' % renderer.charset
+                renderer_content_type += f' ;{renderer.charset}'
         response_headers['Content-Type'] = renderer_content_type
 
         if getattr(view, 'paginator', None) and view.paginator.display_page_controls:

rest_framework/request.py

@@ -180,11 +180,8 @@ class Request:
             self.authenticators = (forced_auth,)
 
     def __repr__(self):
-        return '<%s.%s: %s %r>' % (
-            self.__class__.__module__,
-            self.__class__.__name__,
-            self.method,
-            self.get_full_path())
+        return f'<{self.__class__.__module__}.{self.__class__.__name__}: ' \
+               f"{self.method} '{self.get_full_path()}'>"
 
     def _default_negotiator(self):
         return api_settings.DEFAULT_CONTENT_NEGOTIATION_CLASS()

rest_framework/serializers.py

@@ -1105,20 +1105,17 @@ class ModelSerializer(Serializer):
         if fields and fields != ALL_FIELDS and not isinstance(fields, (list, tuple)):
             raise TypeError(
                 'The `fields` option must be a list or tuple or "__all__". '
-                'Got %s.' % type(fields).__name__
+                f'Got {type(fields).__name__}.'
             )
 
         if exclude and not isinstance(exclude, (list, tuple)):
             raise TypeError(
-                'The `exclude` option must be a list or tuple. Got %s.' %
-                type(exclude).__name__
+                f'The `exclude` option must be a list or tuple. Got {type(exclude).__name__}.'
             )
 
         assert not (fields and exclude), (
-            "Cannot set both 'fields' and 'exclude' options on "
-            "serializer {serializer_class}.".format(
-                serializer_class=self.__class__.__name__
-            )
+            f"Cannot set both 'fields' and 'exclude' options on "
+            f"serializer {self.__class__.__name__}."
         )
 
         assert not (fields is None and exclude is None), (

rest_framework/throttling.py

@@ -91,7 +91,7 @@ class SimpleRateThrottle(BaseThrottle):
         try:
             return self.THROTTLE_RATES[self.scope]
         except KeyError:
-            msg = "No default throttle rate set for '%s' scope" % self.scope
+            msg = f"No default throttle rate set for '{self.scope}' scope"
             raise ImproperlyConfigured(msg)
 
     def parse_rate(self, rate):

rest_framework/urlpatterns.py

@@ -9,7 +9,7 @@ def _get_format_path_converter(suffix_kwarg, allowed):
         if len(allowed) == 1:
             allowed_pattern = allowed[0]
         else:
-            allowed_pattern = '(?:%s)' % '|'.join(allowed)
+            allowed_pattern = f'(?:{"|".join(allowed)})'
         suffix_pattern = r"\.%s/?" % allowed_pattern
     else:
         suffix_pattern = r"\.[a-z0-9]+/?"
@@ -99,7 +99,7 @@ def format_suffix_patterns(urlpatterns, suffix_required=False, allowed=None):
         if len(allowed) == 1:
             allowed_pattern = allowed[0]
         else:
-            allowed_pattern = '(%s)' % '|'.join(allowed)
+            allowed_pattern = f'({"|".join(allowed)})'
         suffix_pattern = r'\.(?P<%s>%s)/?$' % (suffix_kwarg, allowed_pattern)
     else:
         suffix_pattern = r'\.(?P<%s>[a-z0-9]+)/?$' % suffix_kwarg
@@ -107,6 +107,6 @@ def format_suffix_patterns(urlpatterns, suffix_required=False, allowed=None):
     converter_name, suffix_converter = _get_format_path_converter(suffix_kwarg, allowed)
     register_converter(suffix_converter, converter_name)
 
-    suffix_route = '<%s:%s>' % (converter_name, suffix_kwarg)
+    suffix_route = f'<{converter_name}:{suffix_kwarg}>'
 
     return apply_suffix_patterns(urlpatterns, suffix_pattern, suffix_required, suffix_route)

rest_framework/validators.py

@@ -48,7 +48,7 @@ class UniqueValidator:
         """
         Filter the queryset to all instances matching the given attribute.
         """
-        filter_kwargs = {'%s__%s' % (field_name, self.lookup): value}
+        filter_kwargs = {f'{field_name}__{self.lookup}': value}
         return qs_filter(queryset, **filter_kwargs)
 
     def exclude_current_instance(self, queryset, instance):
@@ -74,10 +74,7 @@ class UniqueValidator:
             raise ValidationError(self.message, code='unique')
 
     def __repr__(self):
-        return '<%s(queryset=%s)>' % (
-            self.__class__.__name__,
-            smart_repr(self.queryset)
-        )
+        return f'<{self.__class__.__name__}(queryset={smart_repr(self.queryset)})>'
 
 
 class UniqueTogetherValidator:
@@ -160,11 +157,7 @@ class UniqueTogetherValidator:
             raise ValidationError(message, code='unique')
 
     def __repr__(self):
-        return '<%s(queryset=%s, fields=%s)>' % (
-            self.__class__.__name__,
-            smart_repr(self.queryset),
-            smart_repr(self.fields)
-        )
+        return f'<{self.__class__.__name__}(queryset={smart_repr(self.queryset)}, fields={smart_repr(self.fields)})>'
 
 
 class ProhibitSurrogateCharactersValidator:
@@ -231,12 +224,8 @@ class BaseUniqueForValidator:
             }, code='unique')
 
     def __repr__(self):
-        return '<%s(queryset=%s, field=%s, date_field=%s)>' % (
-            self.__class__.__name__,
-            smart_repr(self.queryset),
-            smart_repr(self.field),
-            smart_repr(self.date_field)
-        )
+        return f'<{self.__class__.__name__}(queryset={smart_repr(self.queryset)}, ' \
+               f'field={smart_repr(self.field)}, date_field={smart_repr(self.date_field)})>'
 
 
 class UniqueForDateValidator(BaseUniqueForValidator):
@@ -246,11 +235,10 @@ class UniqueForDateValidator(BaseUniqueForValidator):
         value = attrs[self.field]
         date = attrs[self.date_field]
 
-        filter_kwargs = {}
-        filter_kwargs[field_name] = value
-        filter_kwargs['%s__day' % date_field_name] = date.day
-        filter_kwargs['%s__month' % date_field_name] = date.month
-        filter_kwargs['%s__year' % date_field_name] = date.year
+        filter_kwargs = {field_name: value,
+                         f'{date_field_name}__day': date.day,
+                         f'{date_field_name}__month': date.month,
+                         f'{date_field_name}__year': date.year}
         return qs_filter(queryset, **filter_kwargs)
 
 
@@ -263,7 +251,7 @@ class UniqueForMonthValidator(BaseUniqueForValidator):
 
         filter_kwargs = {}
         filter_kwargs[field_name] = value
-        filter_kwargs['%s__month' % date_field_name] = date.month
+        filter_kwargs[f'{date_field_name}__month'] = date.month
         return qs_filter(queryset, **filter_kwargs)
 
 
@@ -274,7 +262,5 @@ class UniqueForYearValidator(BaseUniqueForValidator):
         value = attrs[self.field]
         date = attrs[self.date_field]
 
-        filter_kwargs = {}
-        filter_kwargs[field_name] = value
-        filter_kwargs['%s__year' % date_field_name] = date.year
+        filter_kwargs = {field_name: value, f'{date_field_name}__year': date.year}
         return qs_filter(queryset, **filter_kwargs)

rest_framework/viewsets.py

@@ -197,7 +197,7 @@ class ViewSetMixin:
 
         for action in actions:
             try:
-                url_name = '%s-%s' % (self.basename, action.url_name)
+                url_name = f'{self.basename}-{action.url_name}'
                 url = reverse(url_name, self.args, self.kwargs, request=self.request)
                 view = self.__class__(**action.kwargs)
                 action_urls[view.get_view_name()] = url

tests/test_exceptions.py

@@ -70,9 +70,9 @@ class ErrorDetailTests(TestCase):
 
     def test_repr(self):
         assert repr(ErrorDetail('msg1')) == \
-            'ErrorDetail(string={!r}, code=None)'.format('msg1')
+            f"ErrorDetail(string='msg1', code='None')"
         assert repr(ErrorDetail('msg1', 'code')) == \
-            'ErrorDetail(string={!r}, code={!r})'.format('msg1', 'code')
+            f"ErrorDetail(string='msg1', code='code')"
 
     def test_str(self):
         assert str(ErrorDetail('msg1')) == 'msg1'

tests/test_filters.py

@@ -208,7 +208,7 @@ class SearchFilterTests(TestCase):
 
             def as_sql(self, compiler, connection):
                 sql, params = compiler.compile(self.lhs)
-                return "trim(%s, 'a')" % sql, params
+                return f"trim({sql}, 'a')", params
 
         with register_lookup(CharField, TrimA):
             # Search including `a`

tests/utils.py

@@ -13,7 +13,7 @@ class MockObject:
             '%s=%s' % (key, value)
             for key, value in sorted(self._kwargs.items())
         ])
-        return '<MockObject %s>' % kwargs_str
+        return f'<MockObject {kwargs_str}>'
 
 
 class MockQueryset: