Flip arguments for Serializer/Deserializer

rnpridgeon · Ryan P · commit 87de9fab4201 · 2020-03-31T17:23:06.000-04:00
diff --git a/confluent_kafka/deserializing_consumer.py b/confluent_kafka/deserializing_consumer.py
@@ -130,7 +130,7 @@ def poll(self, timeout=-1):
         value = msg.value()
         if self._value_deserializer is not None:
             try:
-                value = self._value_deserializer(ctx, value)
+                value = self._value_deserializer(value, ctx)
             except SerializationError as se:
                 raise ConsumeError(KafkaError._VALUE_DESERIALIZATION,
                                    reason=se.message,
@@ -140,7 +140,7 @@ def poll(self, timeout=-1):
         ctx.field = MessageField.KEY
         if self._key_deserializer is not None:
             try:
-                key = self._key_deserializer(ctx, key)
+                key = self._key_deserializer(key, ctx)
             except SerializationError as se:
                 raise ConsumeError(KafkaError._KEY_DESERIALIZATION,
                                    reason=se.message,
diff --git a/confluent_kafka/schema_registry/avro.py b/confluent_kafka/schema_registry/avro.py
@@ -124,7 +124,7 @@ class AvroSerializer(Serializer):
 
         schema_str (str): Avro Schema declaration.
 
-        to_dict (callable, optional): Callable(SerializationContext, object) -> dict.
+        to_dict (callable, optional): Callable(object, SerializationContext) -> dict.
             Converts object to a dict.
 
         conf (dict): AvroSerializer configuration.
@@ -172,7 +172,7 @@ def __init__(self, schema_registry_client, schema_str,
 
         if len(conf_copy) > 0:
             raise ValueError("Unrecognized properties: {}"
-                             .format(conf_copy.keys()))
+                             .format(", ".format(conf_copy.keys())))
 
         # convert schema_str to Schema instance
         schema = _schema_loads(schema_str)
@@ -188,17 +188,17 @@ def __init__(self, schema_registry_client, schema_str,
         self._schema_name = schema_name
         self._parsed_schema = parsed_schema
 
-    def __call__(self, ctx, obj):
+    def __call__(self, obj, ctx):
         """
         Serializes an object to the Confluent Schema Registry's Avro binary
         format.
 
         Args:
+            obj (object): object instance to serializes.
+
             ctx (SerializationContext): Metadata pertaining to the serialization
                 operation.
 
-            obj (object): object instance to serialize.
-
         Note:
             None objects are represented as Kafka Null.
 
@@ -229,7 +229,7 @@ def __call__(self, ctx, obj):
             self._known_subjects.add(subject)
 
         if self._to_dict is not None:
-            value = self._to_dict(ctx, obj)
+            value = self._to_dict(obj, ctx)
         else:
             value = obj
 
@@ -261,7 +261,7 @@ class AvroDeserializer(Deserializer):
 
         schema_str (str): Avro reader schema declaration.
 
-        from_dict (callable, optional): Callable(SerializationContext, dict) -> object.
+        from_dict (callable, optional): Callable(dict, SerializationContext) -> object.
             Converts dict to an instance of some object.
 
     .. _Schema declaration:
@@ -284,16 +284,16 @@ def __init__(self, schema_registry_client, schema_str, from_dict=None):
                              " from_dict(SerializationContext, dict) -> object")
         self._from_dict = from_dict
 
-    def __call__(self, ctx, value):
+    def __call__(self, value, ctx):
         """
         Decodes a Confluent Schema Registry formatted Avro bytes to an object.
 
         Arguments:
+            value (bytes): bytes
+
             ctx (SerializationContext): Metadata pertaining to the serialization
                 operation.
 
-            value (bytes): bytes
-
         Raises:
             SerializerError if an error occurs ready data.
 
@@ -331,6 +331,6 @@ def __call__(self, ctx, value):
                                          self._reader_schema)
 
             if self._from_dict is not None:
-                return self._from_dict(ctx, obj_dict)
+                return self._from_dict(obj_dict, ctx)
 
             return obj_dict
diff --git a/confluent_kafka/serialization/__init__.py b/confluent_kafka/serialization/__init__.py
@@ -137,16 +137,16 @@ class Serializer(object):
     """
     __slots__ = []
 
-    def __call__(self, ctx, obj):
+    def __call__(self, obj, ctx):
         """
         Converts obj to bytes.
 
         Args:
+            obj (object): object to be serialized
+
             ctx (SerializationContext): Metadata pertaining to the serialization
                 operation
 
-            obj (object): object to be serialized
-
         Raises:
             SerializerError if an error occurs during serialization
 
@@ -200,16 +200,16 @@ class Deserializer(object):
     """
     __slots__ = []
 
-    def __call__(self, ctx, value):
+    def __call__(self, value, ctx):
         """
         Convert bytes to object
 
         Args:
+            value (bytes): bytes to be deserialized
+
             ctx (SerializationContext): Metadata pertaining to the serialization
                 operation
 
-            value (bytes): bytes to be deserialized
-
         Raises:
             SerializerError if an error occurs during deserialization
 
@@ -228,17 +228,16 @@ class DoubleSerializer(Serializer):
         https://docs.confluent.io/current/clients/javadocs/org/apache/kafka/common/serialization/DoubleSerializer.html
 
     """  # noqa: E501
-
-    def __call__(self, ctx, obj):
+    def __call__(self, obj, ctx):
         """
         Serializes float as IEEE 764 binary64 bytes.
 
         Args:
+            obj (object): object to be serialized
+
             ctx (SerializationContext): Metadata pertaining to the serialization
                 operation
 
-            obj (object): object to be serialized
-
         Note:
             None objects are represented as Kafka Null.
 
@@ -266,17 +265,16 @@ class DoubleDeserializer(Deserializer):
         https://docs.confluent.io/current/clients/javadocs/org/apache/kafka/common/serialization/DoubleDeserializer.html
 
     """  # noqa: E501
-
-    def __call__(self, ctx, value):
+    def __call__(self, value, ctx):
         """
         Deserializes float from IEEE 764 binary64 bytes.
 
         Args:
+            value (bytes): bytes to be deserialized
+
             ctx (SerializationContext): Metadata pertaining to the serialization
                 operation
 
-            value (bytes): bytes to be deserialized
-
         Raises:
             SerializerError if an error occurs during deserialization.
 
@@ -301,17 +299,16 @@ class IntegerSerializer(Serializer):
         https://docs.confluent.io/current/clients/javadocs/org/apache/kafka/common/serialization/IntegerSerializer.html
 
     """  # noqa: E501
-
-    def __call__(self, ctx, obj):
+    def __call__(self, obj, ctx):
         """
         Serializes int as int32 bytes.
 
         Args:
+            obj (object): object to be serialized
+
             ctx (SerializationContext): Metadata pertaining to the serialization
                 operation
 
-            obj (object): object to be serialized
-
         Note:
             None objects are represented as Kafka Null.
 
@@ -339,17 +336,15 @@ class IntegerDeserializer(Deserializer):
         https://docs.confluent.io/current/clients/javadocs/org/apache/kafka/common/serialization/IntegerDeserializer.html
 
     """  # noqa: E501
-
-    def __call__(self, ctx, value):
+    def __call__(self, value, ctx):
         """
         Deserializes int from int32 bytes.
 
         Args:
-            ctx (SerializationContext): Metadata pertaining to the serialization
-                operation
-
             value (bytes): bytes to be deserialized
 
+            ctx (SerializationContext): Metadata pertaining to the serialization
+                operation
 
         Raises:
             SerializerError if an error occurs during deserialization.
@@ -387,7 +382,7 @@ class StringSerializer(Serializer):
     def __init__(self, codec='utf_8'):
         self.codec = codec
 
-    def __call__(self, ctx, obj):
+    def __call__(self, obj, ctx):
         """
         Serializes a str(py2:unicode) to bytes.
 
@@ -396,11 +391,11 @@ def __call__(self, ctx, obj):
             Python 3 all str objects are already unicode objects.
 
         Args:
+            obj (object): object to be serialized
+
             ctx (SerializationContext): Metadata pertaining to the serialization
                 operation
 
-            obj (object): object to be serialized
-
         Raises:
             SerializerError if an error occurs during serialization.
 
@@ -435,7 +430,7 @@ class StringDeserializer(Deserializer):
     def __init__(self, codec='utf_8'):
         self.codec = codec
 
-    def __call__(self, ctx, value):
+    def __call__(self, value, ctx):
         """
         Serializes unicode to bytes per the configured codec. Defaults to ``utf_8``.
 
@@ -446,11 +441,11 @@ def __call__(self, ctx, value):
             Python 3 all str objects are already unicode objects.
 
         Args:
+            value (bytes): bytes to be deserialized
+
             ctx (SerializationContext): Metadata pertaining to the serialization
                 operation
 
-            value (bytes): bytes to be deserialized
-
         Raises:
             SerializerError if an error occurs during deserialization.
 
diff --git a/confluent_kafka/serializing_producer.py b/confluent_kafka/serializing_producer.py
@@ -157,11 +157,11 @@ def produce(self, topic, key=None, value=None, partition=-1,
         """
         ctx = SerializationContext(topic, MessageField.KEY)
         if self._key_serializer is not None:
-            key = self._key_serializer(ctx, key)
+            key = self._key_serializer(key, ctx)
 
         ctx.field = MessageField.VALUE
         if self._value_serializer is not None:
-            value = self._value_serializer(ctx, value)
+            value = self._value_serializer(value, ctx)
 
         super(SerializingProducer, self).produce(topic, value, key,
                                                  headers=headers,
diff --git a/examples/avro_consumer.py b/examples/avro_consumer.py
@@ -45,16 +45,16 @@ def __init__(self, name=None, favorite_number=None, favorite_color=None):
         self.favorite_color = favorite_color
 
 
-def dict_to_user(ctx, obj):
+def dict_to_user(obj, ctx):
     """
     Converts object literal(dict) to a User instance.
 
     Args:
+        obj (dict): Object literal(dict)
+
         ctx (SerializationContext): Metadata pertaining to the serialization
             operation.
 
-        obj (dict): Object literal(dict)
-
     """
     if obj is None:
         return None
diff --git a/examples/avro_producer.py b/examples/avro_producer.py
@@ -52,16 +52,16 @@ def __init__(self, name, address, favorite_number, favorite_color):
         self._address = address
 
 
-def user_to_dict(ctx, user):
+def user_to_dict(user, ctx):
     """
     Returns a dict representation of a User instance for serialization.
 
     Args:
+        user (User): User instance.
+
         ctx (SerializationContext): Metadata pertaining to the serialization
             operation.
 
-        user (User): User instance.
-
     Returns:
         dict: Dict populated with user attributes to be serialized.
 
diff --git a/tests/integration/schema_registry/test_avro_serializers.py b/tests/integration/schema_registry/test_avro_serializers.py
@@ -123,9 +123,8 @@ def test_delivery_report_serialization(kafka_cluster, load_avsc, avsc, data, rec
     producer = kafka_cluster.producer(value_serializer=value_serializer)
 
     def assert_cb(err, msg):
-        actual = value_deserializer(SerializationContext(topic,
-                                                         MessageField.VALUE),
-                                    msg.value())
+        actual = value_deserializer(msg.value(),
+                                    SerializationContext(topic, MessageField.VALUE))
 
         if record_type == "record":
             assert [v == actual[k] for k, v in data.items()]
@@ -165,13 +164,13 @@ def test_avro_record_serialization_custom(kafka_cluster):
 
     user = User('Bowie', 47, 'purple')
     value_serializer = AvroSerializer(sr, User.schema_str,
-                                      lambda ctx, user:
+                                      lambda user, ctx:
                                       dict(name=user.name,
                                            favorite_number=user.favorite_number,
                                            favorite_color=user.favorite_color))
 
     value_deserializer = AvroDeserializer(sr, User.schema_str,
-                                          lambda ctx, user_dict:
+                                          lambda user_dict, ctx:
                                           User(**user_dict))
 
     producer = kafka_cluster.producer(value_serializer=value_serializer)
diff --git a/tests/schema_registry/test_avro_serializer.py b/tests/schema_registry/test_avro_serializer.py
@@ -63,8 +63,9 @@ def test_avro_serializer_config_auto_register_schemas_false(mock_schema_registry
     test_serializer = AvroSerializer(test_client, "string",
                                      conf={'auto.register.schemas': False})
 
-    test_serializer(SerializationContext("test-auto-register",
-                                         MessageField.KEY), "test")
+    test_serializer("test",
+                    SerializationContext("test-auto-register",
+                                         MessageField.KEY))
 
     register_count = test_client.counter['POST'].get('/subjects/{}/versions'
                                                      .format(subject), 0)
