replace try/except with context manager

If the desire is to simply suppress an error, rather than perform some sort of branching logic, the Python standard library has a paradigm for that: contextlib.suppress()

rest_framework/fields.py

@@ -1157,20 +1157,14 @@ class DateTimeField(Field):
             return self.enforce_timezone(value)
 
         for input_format in input_formats:
-            if input_format.lower() == ISO_8601:
-                try:
+            with contextlib.suppress(ValueError, TypeError):
+                if input_format.lower() == ISO_8601:
                     parsed = parse_datetime(value)
                     if parsed is not None:
                         return self.enforce_timezone(parsed)
-                except (ValueError, TypeError):
-                    pass
-            else:
-                try:
+                else:
                     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

@@ -4,8 +4,10 @@ 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
 from django.http import QueryDict
@@ -193,17 +195,9 @@ 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']
-        except (AttributeError, KeyError, ValueError):
-            pass
+            return params['filename*'] if 'filename*' in params else params['filename']

rest_framework/serializers.py

@@ -1502,7 +1502,7 @@ class ModelSerializer(Serializer):
                 field = model._meta.get_field(source)
                 if isinstance(field, DjangoModelField):
                     model_fields[source] = field
-                    
+
         return model_fields
 
     # Determine the validators to apply...

rest_framework/viewsets.py

@@ -245,4 +245,4 @@ class ModelViewSet(mixins.CreateModelMixin,
     A viewset that provides default `create()`, `retrieve()`, `update()`,
     `partial_update()`, `destroy()` and `list()` actions.
     """
-    pass 
+    pass