init comment-service

services/comment-service/comment_service/events/post_consumer.py

@@ -0,0 +1,33 @@
+import logging
+
+from comment_service.models.proto import post_pb2
+from comment_service.events.base_consumer import EventConsumer
+
+
+class PostEventConsumer(EventConsumer):
+    """Consumer class responsible for 'post' events.
+    
+    Attributes:
+        CONSUMER_TOPIC: The topic to consume events from.
+        CONSUMER_EVENT_TYPE (post_pb2.PostEvent): Kafka messages are serialised to this type.
+        _db_repo (CommentDBRepository): The repository interface for modifying data.
+        _consumer (aiokafka.AIOKafkaConsumer): The underlying Kafka instance.
+
+    """
+    CONSUMER_TOPIC = "post"
+    CONSUMER_EVENT_TYPE = post_pb2.PostEvent
+
+    async def _process_event(self, event: post_pb2.PostEvent) -> None:
+        """Process a recieved event.
+
+        In response to a Post deleted event, delete any comments
+        that fall under that post.
+
+        Args:
+            event (post_pb2.PostEvent): The decoded protobuf message.
+        
+        """
+        if event.type == "deleted":
+            assert event.data.id != ""
+            await self._db_repo.delete_post_comments(event.data.id)
+            logging.info("succesfully processed PostEvent (type: 'deleted')")