Refactor: Replace try/except with contextlib.suppress() (#8676)

rest_framework/fields.py

@@ -1,3 +1,4 @@
+import contextlib
 import copy
 import datetime
 import decimal
@@ -690,15 +691,13 @@ class BooleanField(Field):
     NULL_VALUES = {'null', 'Null', 'NULL', '', None}
 
     def to_internal_value(self, data):
-        try:
+        with contextlib.suppress(TypeError):
             if data in self.TRUE_VALUES:
                 return True
             elif data in self.FALSE_VALUES:
                 return False
             elif data in self.NULL_VALUES and self.allow_null:
                 return None
-        except TypeError:  # Input is an unhashable type
-            pass
         self.fail('invalid', input=data)
 
     def to_representation(self, value):
@@ -1158,19 +1157,14 @@ class DateTimeField(Field):
             return self.enforce_timezone(value)
 
         for input_format in input_formats:
-            if input_format.lower() == ISO_8601:
+            with contextlib.suppress(ValueError, TypeError):
-                try:
+                if input_format.lower() == ISO_8601:
                     parsed = parse_datetime(value)
                     if parsed is not None:
                         return self.enforce_timezone(parsed)
-                except (ValueError, TypeError):
+
-                    pass
+                parsed = self.datetime_parser(value, input_format)
-            else:
+                return self.enforce_timezone(parsed)
-                try:
-                    parsed = self.datetime_parser(value, input_format)
-                    return self.enforce_timezone(parsed)
-                except (ValueError, TypeError):
-                    pass
 
         humanized_format = humanize_datetime.datetime_formats(input_formats)
         self.fail('invalid', format=humanized_format)

rest_framework/pagination.py

@@ -2,6 +2,8 @@
 Pagination serializers determine the structure of the output that should
 be used for paginated responses.
 """
+
+import contextlib
 from base64 import b64decode, b64encode
 from collections import OrderedDict, namedtuple
 from urllib import parse
@@ -257,15 +259,12 @@ class PageNumberPagination(BasePagination):
 
     def get_page_size(self, request):
         if self.page_size_query_param:
-            try:
+            with contextlib.suppress(KeyError, ValueError):
                 return _positive_int(
                     request.query_params[self.page_size_query_param],
                     strict=True,
                     cutoff=self.max_page_size
                 )
-            except (KeyError, ValueError):
-                pass
-
         return self.page_size
 
     def get_next_link(self):
@@ -430,15 +429,12 @@ class LimitOffsetPagination(BasePagination):
 
     def get_limit(self, request):
         if self.limit_query_param:
-            try:
+            with contextlib.suppress(KeyError, ValueError):
                 return _positive_int(
                     request.query_params[self.limit_query_param],
                     strict=True,
                     cutoff=self.max_limit
                 )
-            except (KeyError, ValueError):
-                pass
-
         return self.default_limit
 
     def get_offset(self, request):
@@ -680,15 +676,12 @@ class CursorPagination(BasePagination):
 
     def get_page_size(self, request):
         if self.page_size_query_param:
-            try:
+            with contextlib.suppress(KeyError, ValueError):
                 return _positive_int(
                     request.query_params[self.page_size_query_param],
                     strict=True,
                     cutoff=self.max_page_size
                 )
-            except (KeyError, ValueError):
-                pass
-
         return self.page_size
 
     def get_next_link(self):

rest_framework/parsers.py

@@ -4,7 +4,9 @@ Parsers are used to parse the content of incoming HTTP requests.
 They give us a generic way of being able to handle various media types
 on the request, such as form content or json encoded data.
 """
+
 import codecs
+import contextlib
 
 from django.conf import settings
 from django.core.files.uploadhandler import StopFutureHandlers
@@ -193,17 +195,12 @@ class FileUploadParser(BaseParser):
         Detects the uploaded file name. First searches a 'filename' url kwarg.
         Then tries to parse Content-Disposition header.
         """
-        try:
+        with contextlib.suppress(KeyError):
             return parser_context['kwargs']['filename']
-        except KeyError:
-            pass
 
-        try:
+        with contextlib.suppress(AttributeError, KeyError, ValueError):
             meta = parser_context['request'].META
             disposition, params = parse_header_parameters(meta['HTTP_CONTENT_DISPOSITION'])
             if 'filename*' in params:
                 return params['filename*']
-            else:
+            return params['filename']
-                return params['filename']
-        except (AttributeError, KeyError, ValueError):
-            pass

rest_framework/relations.py

@@ -1,3 +1,4 @@
+import contextlib
 import sys
 from collections import OrderedDict
 from urllib import parse
@@ -170,7 +171,7 @@ class RelatedField(Field):
     def get_attribute(self, instance):
         if self.use_pk_only_optimization() and self.source_attrs:
             # Optimized case, return a mock object only containing the pk attribute.
-            try:
+            with contextlib.suppress(AttributeError):
                 attribute_instance = get_attribute(instance, self.source_attrs[:-1])
                 value = attribute_instance.serializable_value(self.source_attrs[-1])
                 if is_simple_callable(value):
@@ -183,9 +184,6 @@ class RelatedField(Field):
                 value = getattr(value, 'pk', value)
 
                 return PKOnlyObject(pk=value)
-            except AttributeError:
-                pass
-
         # Standard case, return the object instance.
         return super().get_attribute(instance)
 

rest_framework/renderers.py

@@ -6,7 +6,9 @@ on the response, such as JSON encoded data or HTML output.
 
 REST framework also provides an HTML renderer that renders the browsable API.
 """
+
 import base64
+import contextlib
 from collections import OrderedDict
 from urllib import parse
 
@@ -72,11 +74,8 @@ class JSONRenderer(BaseRenderer):
             # then pretty print the result.
             # Note that we coerce `indent=0` into `indent=None`.
             base_media_type, params = parse_header_parameters(accepted_media_type)
-            try:
+            with contextlib.suppress(KeyError, ValueError, TypeError):
                 return zero_as_none(max(min(int(params['indent']), 8), 0))
-            except (KeyError, ValueError, TypeError):
-                pass
-
         # If 'indent' is provided in the context, then pretty print the result.
         # E.g. If we're being called by the BrowsableAPIRenderer.
         return renderer_context.get('indent', None)
@@ -488,11 +487,8 @@ class BrowsableAPIRenderer(BaseRenderer):
                 return
 
             if existing_serializer is not None:
-                try:
+                with contextlib.suppress(TypeError):
                     return self.render_form_for_serializer(existing_serializer)
-                except TypeError:
-                    pass
-
             if has_serializer:
                 if method in ('PUT', 'PATCH'):
                     serializer = view.get_serializer(instance=instance, **kwargs)

rest_framework/serializers.py

@@ -10,6 +10,8 @@ python primitives.
 2. The process of marshalling between python primitives and request and
 response content is handled by parsers and renderers.
 """
+
+import contextlib
 import copy
 import inspect
 import traceback
@@ -1496,12 +1498,10 @@ class ModelSerializer(Serializer):
                 # they can't be nested attribute lookups.
                 continue
 
-            try:
+            with contextlib.suppress(FieldDoesNotExist):
                 field = model._meta.get_field(source)
                 if isinstance(field, DjangoModelField):
                     model_fields[source] = field
-            except FieldDoesNotExist:
-                pass
 
         return model_fields
 

rest_framework/utils/encoders.py

@@ -1,6 +1,8 @@
 """
 Helper classes for parsers.
 """
+
+import contextlib
 import datetime
 import decimal
 import json  # noqa
@@ -58,10 +60,8 @@ class JSONEncoder(json.JSONEncoder):
             )
         elif hasattr(obj, '__getitem__'):
             cls = (list if isinstance(obj, (list, tuple)) else dict)
-            try:
+            with contextlib.suppress(Exception):
                 return cls(obj)
-            except Exception:
-                pass
         elif hasattr(obj, '__iter__'):
             return tuple(item for item in obj)
         return super().default(obj)

rest_framework/utils/serializer_helpers.py

@@ -1,3 +1,4 @@
+import contextlib
 import sys
 from collections import OrderedDict
 from collections.abc import Mapping, MutableMapping
@@ -103,15 +104,13 @@ class JSONBoundField(BoundField):
         # When HTML form input is used and the input is not valid
         # value will be a JSONString, rather than a JSON primitive.
         if not getattr(value, 'is_json_string', False):
-            try:
+            with contextlib.suppress(TypeError, ValueError):
                 value = json.dumps(
                     self.value,
                     sort_keys=True,
                     indent=4,
                     separators=(',', ': '),
                 )
-            except (TypeError, ValueError):
-                pass
         return self.__class__(self._field, value, self.errors, self._prefix)