[server]: Make return_newest_data accept a list of objectTypes

server/src/functions/return_newest_data/lambda_function.py

@@ -1,6 +1,7 @@
 import boto3
 import json
 import os
+from boto3.dynamodb.conditions import Key, Attr
 
 dynamodb = boto3.resource('dynamodb')
 table = dynamodb.Table(os.environ['TABLE_NAME'])
@@ -9,52 +10,92 @@ gsi_name = "objectType-index"
 def lambda_handler(event, context):
     try:
         query_params = event.get('queryStringParameters', {}) or {}
-        object_type = query_params.get('objectType')
+        object_type_param = query_params.get('objectType')
+
+        # Handle multiple object types if provided
+        if object_type_param:
+            object_types = [obj.strip() for obj in object_type_param.split(',')]
+        else:
+            object_types = []
 
         # Step 1: Retrieve the latest timestamp
-        if object_type:
+        items = []
-            response = table.query(
+
-                IndexName=gsi_name,
+        if object_types:
-                KeyConditionExpression="objectType = :obj",
+            # Scan with a filter for multiple object types to get timestamps
+            response = table.scan(
+                FilterExpression=Attr('objectType').is_in(object_types),
+                ProjectionExpression="#ts",
+                ExpressionAttributeNames={"#ts": "timestamp"}
+            )
+            items.extend(response.get('Items', []))
+
+            # Handle pagination if necessary
+            while 'LastEvaluatedKey' in response:
+                response = table.scan(
+                    FilterExpression=Attr('objectType').is_in(object_types),
                     ProjectionExpression="#ts",
                     ExpressionAttributeNames={"#ts": "timestamp"},
-                ExpressionAttributeValues={":obj": object_type},
+                    ExclusiveStartKey=response['LastEvaluatedKey']
-                Limit=1,
-                ScanIndexForward=False  # Get the latest timestamp
                 )
+                items.extend(response.get('Items', []))
         else:
+            # Scan the entire table if no object types are specified
             response = table.scan(
                 ProjectionExpression="#ts",
                 ExpressionAttributeNames={"#ts": "timestamp"}
             )
+            items.extend(response.get('Items', []))
 
-        if not response.get('Items'):
+            # Handle pagination if necessary
+            while 'LastEvaluatedKey' in response:
+                response = table.scan(
+                    ProjectionExpression="#ts",
+                    ExpressionAttributeNames={"#ts": "timestamp"},
+                    ExclusiveStartKey=response['LastEvaluatedKey']
+                )
+                items.extend(response.get('Items', []))
+
+        if not items:
             return {'statusCode': 200, 'body': json.dumps([])}
 
         # Extract the newest timestamp
-        newest_timestamp = max(int(item['timestamp']) for item in response['Items'])
+        newest_timestamp = max(int(item['timestamp']) for item in items)
 
-        # Convert newest_timestamp to the correct type for DynamoDB comparison
+        # Step 2: Fetch items with the newest timestamp for the specified object types
-        if object_type:
+        items_with_latest_timestamp = []
-            response = table.query(
+
-                IndexName=gsi_name,
+        if object_types:
-                KeyConditionExpression="objectType = :obj AND #ts = :ts",
-                ExpressionAttributeNames={"#ts": "timestamp"},
-                ExpressionAttributeValues={
-                    ":obj": object_type,
-                    ":ts": str(newest_timestamp)  # Ensure correct type
-                }
-            )
-        else:
             response = table.scan(
-                FilterExpression="#ts = :ts",
+                FilterExpression=Attr('objectType').is_in(object_types) & Attr('timestamp').eq(str(newest_timestamp))
-                ExpressionAttributeNames={"#ts": "timestamp"},
-                ExpressionAttributeValues={":ts": str(newest_timestamp)}  # Ensure correct type
             )
+            items_with_latest_timestamp.extend(response.get('Items', []))
+
+            # Handle pagination if necessary
+            while 'LastEvaluatedKey' in response:
+                response = table.scan(
+                    FilterExpression=Attr('objectType').is_in(object_types) & Attr('timestamp').eq(str(newest_timestamp)),
+                    ExclusiveStartKey=response['LastEvaluatedKey']
+                )
+                items_with_latest_timestamp.extend(response.get('Items', []))
+        else:
+            # Scan the entire table for the latest timestamp if no object types are specified
+            response = table.scan(
+                FilterExpression=Attr('timestamp').eq(str(newest_timestamp))
+            )
+            items_with_latest_timestamp.extend(response.get('Items', []))
+
+            # Handle pagination if necessary
+            while 'LastEvaluatedKey' in response:
+                response = table.scan(
+                    FilterExpression=Attr('timestamp').eq(str(newest_timestamp)),
+                    ExclusiveStartKey=response['LastEvaluatedKey']
+                )
+                items_with_latest_timestamp.extend(response.get('Items', []))
 
         return {
             'statusCode': 200,
-            'body': json.dumps(response['Items'])
+            'body': json.dumps(items_with_latest_timestamp)
         }
 
     except Exception as e: