Ticket #15889: 15889-get_serializer-specific-exception_2.diff

django/core/serializers/__init__.py

@@ -18 +18 @@
 
 from django.conf import settings
 from django.utils import importlib
+from django.core.serializers.base import SerializerNotFound
 
 # Built-in serializers
 BUILTIN_SERIALIZERS = {
@@ -65 +66 @@
 def get_serializer(format):
     if not _serializers:
         _load_serializers()
+    if format not in _serializers:
+        raise SerializerNotFound(format)
     return _serializers[format].Serializer
 
 def get_serializer_formats():

django/core/serializers/base.py

@@ -8 +8 @@
 from django.utils.encoding import smart_str, smart_unicode
 from django.utils import datetime_safe
 
+class SerializerNotFound(KeyError):
+    """A requested serializer was not found."""
+    pass
+
 class SerializationError(Exception):
     """Something bad happened during serialization."""
     pass

docs/topics/serialization.txt

@@ -38 +38 @@
     out = open("file.xml", "w")
     xml_serializer.serialize(SomeModel.objects.all(), stream=out)
 
+.. note::
+
+    Calling :func:`~django.core.serializers.get_serializer` with an unknown
+    :ref:`format <serialization-formats>` will raise a
+    :class:`~django.core.serializers.SerializerNotFound` exception.
+
 Subset of fields
 ~~~~~~~~~~~~~~~~
 

tests/regressiontests/serializers_regress/tests.py

@@ -17 +17 @@
 
 from django.conf import settings
 from django.core import serializers, management
+from django.core.serializers import SerializerNotFound
 from django.db import transaction, DEFAULT_DB_ALIAS, connection
 from django.test import TestCase
 from django.utils.functional import curry
@@ -350 +351 @@
 # Dynamically create serializer tests to ensure that all
 # registered serializers are automatically tested.
 class SerializerTests(TestCase):
-    pass
-
+    def test_get_unknown_serializer(self):
+        """
+        #15889: get_serializer('unknown_format') raises a SerializerNotFound
+        """
+        unknown = 'unknown format'
+        self.assertRaises(SerializerNotFound,
+                          serializers.get_serializer, unknown)
+        # SerializerNotFound subclasses KeyError for backwards compatibility
+        self.assertRaises(KeyError, serializers.get_serializer, 'unknown')
+
+        # SerializerNotFound is instantiated with the non-existent format
+        try:
+            serializers.get_serializer(unknown)
+        except SerializerNotFound as (msg,):
+            self.assertEqual(msg, unknown)
+
+    def test_get_known_serializer(self):
+        """
+        #15889: make sure getting an existing serializer still works fine
+        """
+        format, module = serializers.BUILTIN_SERIALIZERS.items()[0]
+        self.assertEqual(serializers.get_serializer(format).__module__, module)
+        
 def serializerTest(format, self):
 
     # Create all the objects defined in the test data