add relationship

enrollments-events/app/enrollment.py

@@ -73,15 +73,34 @@ def enroll(
             }
         )
 
-        for entity in linked_entities:
-            keyprefix = entity.type.lower()
+        # Relationships between this enrollment and its related entities
+        for parent_entity in linked_entities:
+            perent_id = parent_entity.id
+            entity_sk = f'LINKED_ENTITIES#{parent_entity.type}'
+            keyprefix = parent_entity.type.lower()
+
+            # Child knows the parent
             transact.put(
                 item={
                     'id': enrollment.id,
-                    'sk': f'LINKED_ENTITIES#{entity.type}',
+                    'sk': entity_sk,
+                    'kind': 'PARENT',
                     'created_at': now_,
-                    f'{keyprefix}_id': entity.id,
-                }
+                    f'{keyprefix}_id': perent_id,
+                },
+                cond_expr='attribute_not_exists(sk)',
+            )
+
+            # Parent knows the child
+            transact.put(
+                item={
+                    'id': perent_id,
+                    'sk': entity_sk,
+                    'kind': 'CHILD',
+                    'created_at': now_,
+                    f'{keyprefix}_id': enrollment.id,
+                },
+                cond_expr='attribute_not_exists(sk)',
             )
 
         if org: