Replace string interpolation and .format calls with f-strings

Author: akx

example/pexp/management/commands/p2cmd.py

@@ -35,8 +35,8 @@ def wrapper(*arg):
         for r in results:
             res_sum += r
         print(
-            "%s%-19s: %.4f ms, %i queries (%i times)"
-            % (message, func.func_name, res_sum, len(connection.queries), iterations)
+            f"{message}{func.func_name:<19}: {res_sum:.4f} ms, "
+            f"{len(connection.queries)} queries ({iterations} times)"
         )
         sys.stdout.flush()
 
@@ -106,13 +106,12 @@ def poly_sql_query():
 def poly_sql_query2():
     cursor = connection.cursor()
     cursor.execute(
-        """
+        f"""
         SELECT id, pexp_testmodela.field1
         FROM pexp_testmodela
-        WHERE pexp_testmodela.field1=%i
+        WHERE pexp_testmodela.field1={rnd.randint(0, 100)}
         ORDER BY pexp_testmodela.id
         """
-        % rnd.randint(0, 100)
     )
     # row=cursor.fetchone()
     return

example/pexp/management/commands/polybench.py

@@ -39,8 +39,8 @@ def wrapper(*arg):
             res_sum += r
         median = res_sum / len(results)
         print(
-            "%s%-19s: %.0f ms, %i queries"
-            % (message, func.func_name, median, len(connection.queries) / len(results))
+            f"{message}{func.func_name:<19}: {median:.0f} ms, "
+            f"{len(connection.queries) / len(results):d} queries"
         )
         sys.stdout.flush()
 
@@ -61,7 +61,9 @@ def run_vanilla_any_poly(func, iterations=1):
 def bench_create(model):
     for i in range(num_objects):
         model.objects.create(
-            field1="abc" + str(i), field2="abcd" + str(i), field3="abcde" + str(i)
+            field1=f"abc{i}",
+            field2=f"abcd{i}",
+            field3=f"abcde{i}",
         )
     # print 'count:',model.objects.count()
 

polymorphic/admin/childadmin.py

@@ -90,10 +90,10 @@ def change_form_template(self):
 
         return [
             f"admin/{app_label}/{opts.object_name.lower()}/change_form.html",
-            "admin/%s/change_form.html" % app_label,
+            f"admin/{app_label}/change_form.html",
             # Added:
-            "admin/%s/%s/change_form.html" % (base_app_label, base_opts.object_name.lower()),
-            "admin/%s/change_form.html" % base_app_label,
+            f"admin/{base_app_label}/{base_opts.object_name.lower()}/change_form.html",
+            f"admin/{base_app_label}/change_form.html",
             "admin/polymorphic/change_form.html",
             "admin/change_form.html",
         ]
@@ -108,12 +108,11 @@ def delete_confirmation_template(self):
         base_app_label = base_opts.app_label
 
         return [
-            "admin/%s/%s/delete_confirmation.html" % (app_label, opts.object_name.lower()),
-            "admin/%s/delete_confirmation.html" % app_label,
+            f"admin/{app_label}/{opts.object_name.lower()}/delete_confirmation.html",
+            f"admin/{app_label}/delete_confirmation.html",
             # Added:
-            "admin/%s/%s/delete_confirmation.html"
-            % (base_app_label, base_opts.object_name.lower()),
-            "admin/%s/delete_confirmation.html" % base_app_label,
+            f"admin/{base_app_label}/{base_opts.object_name.lower()}/delete_confirmation.html",
+            f"admin/{base_app_label}/delete_confirmation.html",
             "admin/polymorphic/delete_confirmation.html",
             "admin/delete_confirmation.html",
         ]
@@ -129,10 +128,10 @@ def object_history_template(self):
 
         return [
             f"admin/{app_label}/{opts.object_name.lower()}/object_history.html",
-            "admin/%s/object_history.html" % app_label,
+            f"admin/{app_label}/object_history.html",
             # Added:
-            "admin/%s/%s/object_history.html" % (base_app_label, base_opts.object_name.lower()),
-            "admin/%s/object_history.html" % base_app_label,
+            f"admin/{base_app_label}/{base_opts.object_name.lower()}/object_history.html",
+            f"admin/{base_app_label}/object_history.html",
             "admin/polymorphic/object_history.html",
             "admin/object_history.html",
         ]

polymorphic/admin/filters.py

@@ -32,6 +32,6 @@ def queryset(self, request, queryset):
                 if choice_value == value:
                     return queryset.filter(polymorphic_ctype_id=choice_value)
             raise PermissionDenied(
-                'Invalid ContentType "{}". It must be registered as child model.'.format(value)
+                f'Invalid ContentType "{value}". It must be registered as child model.'
             )
         return queryset

polymorphic/admin/helpers.py

@@ -91,7 +91,7 @@ def inline_formset_data(self):
         verbose_name = self.opts.verbose_name
         return json.dumps(
             {
-                "name": "#%s" % self.formset.prefix,
+                "name": f"#{self.formset.prefix}",
                 "options": {
                     "prefix": self.formset.prefix,
                     "addText": gettext("Add another %(verbose_name)s")

polymorphic/admin/inlines.py

@@ -38,7 +38,7 @@ class PolymorphicInlineModelAdmin(InlineModelAdmin):
     #: This can be redefined for subclasses.
     polymorphic_media = Media(
         js=(
-            "admin/js/vendor/jquery/jquery{}.js".format("" if settings.DEBUG else ".min"),
+            f"admin/js/vendor/jquery/{'jquery' if settings.DEBUG else 'jquery.min'}.js",
             "admin/js/jquery.init.js",
             "polymorphic/js/polymorphic_inlines.js",
         ),

polymorphic/admin/parentadmin.py

@@ -97,14 +97,10 @@ def register_child(self, model, model_admin):
             raise RegistrationClosed("The admin model can't be registered anymore at this point.")
 
         if not issubclass(model, self.base_model):
-            raise TypeError(
-                "{} should be a subclass of {}".format(model.__name__, self.base_model.__name__)
-            )
+            raise TypeError(f"{model.__name__} should be a subclass of {self.base_model.__name__}")
         if not issubclass(model_admin, admin.ModelAdmin):
             raise TypeError(
-                "{} should be a subclass of {}".format(
-                    model_admin.__name__, admin.ModelAdmin.__name__
-                )
+                f"{model_admin.__name__} should be a subclass of {admin.ModelAdmin.__name__}"
             )
 
         self._child_admin_site.register(model, model_admin)
@@ -159,7 +155,8 @@ def _get_real_admin_by_ct(self, ct_id, super_if_self=True):
         model_class = ct.model_class()
         if not model_class:
             # Handle model deletion
-            raise Http404("No model found for '{}.{}'.".format(*ct.natural_key()))
+            app_label, model = ct.natural_key()
+            raise Http404(f"No model found for '{app_label}.{model}'.")
 
         return self._get_real_admin_by_model(model_class, super_if_self=super_if_self)
 
@@ -168,7 +165,7 @@ def _get_real_admin_by_model(self, model_class, super_if_self=True):
         # Hence, make sure this is a derived object, or risk exposing other admin interfaces.
         if model_class not in self._child_models:
             raise PermissionDenied(
-                "Invalid model '{}', it must be registered as child model.".format(model_class)
+                f"Invalid model '{model_class}', it must be registered as child model."
             )
 
         try:
@@ -177,7 +174,7 @@ def _get_real_admin_by_model(self, model_class, super_if_self=True):
             real_admin = self._child_admin_site._registry[model_class]
         except KeyError:
             raise ChildAdminNotRegistered(
-                "No child admin site was registered for a '{}' model.".format(model_class)
+                f"No child admin site was registered for a '{model_class}' model."
             )
 
         if super_if_self and real_admin is self:
@@ -273,7 +270,7 @@ def subclass_view(self, request, path):
                     object_id = int(path[0:pos])
             except ValueError:
                 raise Http404(
-                    "No ct_id parameter, unable to find admin subclass for path '{}'.".format(path)
+                    f"No ct_id parameter, unable to find admin subclass for path '{path}'."
                 )
 
             ct_id = self.model.objects.values_list("polymorphic_ctype_id", flat=True).get(
@@ -299,7 +296,8 @@ def add_type_view(self, request, form_url=""):
         if request.META["QUERY_STRING"]:
             # QUERY_STRING is bytes in Python 3, using force_str() to decode it as string.
             # See QueryDict how Django deals with that.
-            extra_qs = "&{}".format(force_str(request.META["QUERY_STRING"]))
+            # TODO: should this use a Django method instead of manipulating the string directly?
+            extra_qs = f"&{force_str(request.META['QUERY_STRING'])}"
 
         choices = self.get_child_type_choices(request, "add")
         if len(choices) == 0:
@@ -315,7 +313,7 @@ def add_type_view(self, request, form_url=""):
         form.fields["ct_id"].choices = choices
 
         if form.is_valid():
-            return HttpResponseRedirect("?ct_id={}{}".format(form.cleaned_data["ct_id"], extra_qs))
+            return HttpResponseRedirect(f"?ct_id={form.cleaned_data['ct_id']}{extra_qs}")
 
         # Wrap in all admin layout
         fieldsets = ((None, {"fields": ("ct_id",)}),)
@@ -351,7 +349,7 @@ def render_add_type_form(self, request, context, form_url=""):
 
         templates = self.add_type_template or [
             f"admin/{app_label}/{opts.object_name.lower()}/add_type_form.html",
-            "admin/%s/add_type_form.html" % app_label,
+            f"admin/{app_label}/add_type_form.html",
             "admin/polymorphic/add_type_form.html",  # added default here
             "admin/add_type_form.html",
         ]
@@ -370,9 +368,9 @@ def change_list_template(self):
 
         return [
             f"admin/{app_label}/{opts.object_name.lower()}/change_list.html",
-            "admin/%s/change_list.html" % app_label,
+            f"admin/{app_label}/change_list.html",
             # Added base class:
-            "admin/%s/%s/change_list.html" % (base_app_label, base_opts.object_name.lower()),
-            "admin/%s/change_list.html" % base_app_label,
+            f"admin/{base_app_label}/{base_opts.object_name.lower()}/change_list.html",
+            f"admin/{base_app_label}/change_list.html",
             "admin/change_list.html",
         ]

polymorphic/base.py

@@ -119,8 +119,10 @@ def validate_model_fields(self, new_class):
         "check if all fields names are allowed (i.e. not in POLYMORPHIC_SPECIAL_Q_KWORDS)"
         for f in new_class._meta.fields:
             if f.name in POLYMORPHIC_SPECIAL_Q_KWORDS:
-                e = 'PolymorphicModel: "%s" - field name "%s" is not allowed in polymorphic models'
-                raise AssertionError(e % (new_class.__name__, f.name))
+                raise AssertionError(
+                    f'PolymorphicModel: "{new_class.__name__}" - '
+                    f'field name "{f.name}" is not allowed in polymorphic models'
+                )
 
     @classmethod
     def validate_model_manager(self, manager, model_name, manager_name):
@@ -133,10 +135,8 @@ def validate_model_manager(self, manager, model_name, manager_name):
             else:
                 extra = ""
             e = (
-                'PolymorphicModel: "{0}.{1}" manager is of type "{2}", but must be a subclass of'
-                " PolymorphicManager.{extra} to support retrieving subclasses".format(
-                    model_name, manager_name, type(manager).__name__, extra=extra
-                )
+                f'PolymorphicModel: "{model_name}.{manager_name}" manager is of type "{type(manager).__name__}", '
+                f"but must be a subclass of PolymorphicManager.{extra} to support retrieving subclasses"
             )
             warnings.warn(e, ManagerInheritanceWarning, stacklevel=3)
             return manager
@@ -145,10 +145,8 @@ def validate_model_manager(self, manager, model_name, manager_name):
             manager.queryset_class, PolymorphicQuerySet
         ):
             e = (
-                'PolymorphicModel: "{}.{}" has been instantiated with a queryset class '
-                "which is not a subclass of PolymorphicQuerySet (which is required)".format(
-                    model_name, manager_name
-                )
+                f'PolymorphicModel: "{model_name}.{manager_name}" has been instantiated with a queryset class '
+                f"which is not a subclass of PolymorphicQuerySet (which is required)"
             )
             warnings.warn(e, ManagerInheritanceWarning, stacklevel=3)
         return manager
@@ -157,7 +155,7 @@ def validate_model_manager(self, manager, model_name, manager_name):
     def base_objects(self):
         warnings.warn(
             "Using PolymorphicModel.base_objects is deprecated.\n"
-            "Use {}.objects.non_polymorphic() instead.".format(self.__class__.__name__),
+            f"Use {self.__class__.__name__}.objects.non_polymorphic() instead.",
             DeprecationWarning,
             stacklevel=2,
         )
@@ -193,7 +191,7 @@ def _default_manager(self):
         manager = super()._default_manager
         if not isinstance(manager, PolymorphicManager):
             warnings.warn(
-                "{}._default_manager is not a PolymorphicManager".format(self.__class__.__name__),
+                f"{self.__class__.__name__}._default_manager is not a PolymorphicManager",
                 ManagerInheritanceWarning,
             )
 

polymorphic/formsets/generic.py

@@ -42,7 +42,7 @@ def get_form(self, ct_field="content_type", fk_field="object_id", **kwargs):
             not isinstance(ct_field, models.ForeignKey)
             or ct_field.remote_field.model != ContentType
         ):
-            raise Exception("fk_name '%s' is not a ForeignKey to ContentType" % ct_field)
+            raise Exception(f"fk_name '{ct_field}' is not a ForeignKey to ContentType")
 
         fk_field = opts.get_field(self.fk_field)  # let the exception propagate
         exclude.extend([ct_field.name, fk_field.name])

polymorphic/formsets/models.py

@@ -188,7 +188,7 @@ def _construct_form(self, i, **kwargs):
                     ct_id = int(self.data[f"{prefix}-polymorphic_ctype"])
                 except (KeyError, ValueError):
                     raise ValidationError(
-                        "Formset row {} has no 'polymorphic_ctype' defined!".format(prefix)
+                        f"Formset row {prefix} has no 'polymorphic_ctype' defined!"
                     )
 
                 model = ContentType.objects.get_for_id(ct_id).model_class()
@@ -243,10 +243,8 @@ def get_form_class(self, model):
         except KeyError:
             # This may happen when the query returns objects of a type that was not handled by the formset.
             raise UnsupportedChildType(
-                "The '{}' found a '{}' model in the queryset, "
-                "but no form class is registered to display it.".format(
-                    self.__class__.__name__, model.__name__
-                )
+                f"The '{self.__class__.__name__}' found a '{model.__name__}' model in the queryset, "
+                f"but no form class is registered to display it."
             )
 
     def is_multipart(self):