Ensure the new eventhub parser backward compatible with the old eventhub extensions

azure/functions/eventhub.py

@@ -105,12 +105,12 @@ class EventHubTriggerConverter(EventHubConverter,
                       typing.List[_eventhub.EventHubEvent]]:
         data_type = data.type
 
-        if cls._is_cardinality_one(trigger_metadata):
-            return cls.decode_single_event(data, trigger_metadata)
-
-        elif cls._is_cardinality_many(trigger_metadata):
+        if cls._is_cardinality_many(trigger_metadata, data_type):
             return cls.decode_multiple_events(data, trigger_metadata)
-
+        elif cls._is_cardinality_one(trigger_metadata, data_type):
+            return cls.decode_single_event(data, trigger_metadata)
+        elif data_type == 'json':  # decode json as single event by default
+            return cls.decode_single_event(data, trigger_metadata)
         else:
             raise NotImplementedError(
                 f'unsupported event data payload type: {data_type}')
@@ -154,9 +154,11 @@ class EventHubTriggerConverter(EventHubConverter,
         elif data.type == 'json':
             parsed_data = json.loads(data.value)
 
-        sys_props = trigger_metadata.get('SystemPropertiesArray')
-
-        parsed_sys_props = json.loads(sys_props.value)
+        parsed_sys_props = {}
+        if trigger_metadata.get('SystemPropertiesArray'):
+            parsed_sys_props = (
+                json.loads(trigger_metadata['SystemPropertiesArray'].value)
+            )
 
         if len(parsed_data) != len(parsed_sys_props):
             raise AssertionError('Number of bodies and metadata mismatched')
@@ -245,9 +247,17 @@ class EventHubTriggerConverter(EventHubConverter,
         return iothub_metadata
 
     @classmethod
-    def _is_cardinality_many(cls, trigger_metadata) -> bool:
-        return 'SystemPropertiesArray' in trigger_metadata
+    def _is_cardinality_many(cls, trigger_metadata, data_type) -> bool:
+        # If the data_type is json and the json contains multiple objects
+        # The SystemPropertiesArray should be set and it gets here
+        return ('SystemPropertiesArray' in trigger_metadata
+                or data_type == 'collection_string'
+                or data_type == 'collection_bytes')
 
     @classmethod
-    def _is_cardinality_one(cls, trigger_metadata) -> bool:
-        return 'SystemProperties' in trigger_metadata
+    def _is_cardinality_one(cls, trigger_metadata, data_type) -> bool:
+        # If the data_type is json and the json contains a single object
+        # The SystemProperties should be set and it gets here
+        return ('SystemProperties' in trigger_metadata
+                or data_type == 'string'
+                or data_type == 'bytes')

tests/test_eventhub.py

@@ -177,6 +177,41 @@ class TestEventHub(unittest.TestCase):
             result[1].iothub_metadata['connection-device-id'], 'MyTestDevice2'
         )
 
+    def test_bytes_without_system_properties(self):
+        result = azf_eh.EventHubTriggerConverter.decode(
+            data=self._generate_single_iothub_datum('bytes'),
+            trigger_metadata={}
+        )
+        self.assertEqual(
+            result.get_body().decode('utf-8'), '{"device-status": "good"}'
+        )
+
+    def test_string_without_system_properties(self):
+        result = azf_eh.EventHubTriggerConverter.decode(
+            data=self._generate_single_iothub_datum('string'),
+            trigger_metadata={}
+        )
+        self.assertEqual(
+            result.get_body().decode('utf-8'), '{"device-status": "good"}'
+        )
+
+    def test_json_without_system_properties(self):
+        result = azf_eh.EventHubTriggerConverter.decode(
+            data=self._generate_single_iothub_datum('json'),
+            trigger_metadata={}
+        )
+        self.assertEqual(
+            result.get_body().decode('utf-8'), '{"device-status": "good"}'
+        )
+
+    def test_mismatch_number_of_bodies_in_metadata(self):
+        # 2 events with no metadata
+        with self.assertRaises(AssertionError):
+            azf_eh.EventHubTriggerConverter.decode(
+                data=self._generate_multiple_iothub_data('collection_string'),
+                trigger_metadata={}
+            )
+
     def _generate_single_iothub_datum(self, datum_type='json'):
         datum = '{"device-status": "good"}'
         if datum_type == 'bytes':