update fix to unit price

courses-events/app/events/daily_sync_course_metadata.py

@@ -5,7 +5,7 @@ from aws_lambda_powertools.utilities.data_classes import (
 )
 from aws_lambda_powertools.utilities.typing import LambdaContext
 from layercake.dateutils import now
-from layercake.dynamodb import DynamoDBPersistenceLayer
+from layercake.dynamodb import DynamoDBPersistenceLayer, KeyPair
 
 from boto3clients import dynamodb_client
 from config import API_URL, COURSE_TABLE
@@ -21,15 +21,16 @@ def lambda_handler(event: DynamoDBStreamEvent, context: LambdaContext) -> bool:
     data = r.json()
     now_ = now()
 
-    with course_layer.batch_writer() as batch:
+    with course_layer.transact_writer() as transact:
         for course in data:
-            batch.put_item(
-                {
-                    'id': {'S': course['id']},
-                    'sk': {'S': 'metadata#unit_price'},
-                    'unit_price': {'N': str(course['metadata']['unit_price'])},
-                    'create_date': {'S': now_.isoformat()},
-                }
+            transact.update(
+                key=KeyPair(course['id'], '0'),
+                update_expr='SET metadata__unit_price = :unit_price, \
+                             updated_at = :updated_at',
+                expr_attr_values={
+                    ':unit_price': course['metadata']['unit_price'],
+                    ':updated_at': now_,
+                },
             )
 
     return True