AWS Lambda with DynamoDB: 'Conditional Check scenarios' scenarios When Updating Items
I'm having a hard time understanding I've been banging my head against this for hours..... Quick question that's been bugging me - I'm currently working on an AWS Lambda function that updates items in a DynamoDB table based on a specific condition. However, I'm working with a 'Conditional Check Failed' behavior when trying to execute the update. My goal is to increment a counter attribute only if it currently equals a specific value. Here’s the code snippet I’m using for the update operation: ```python import boto3 # Initialize DynamoDB resource dynamodb = boto3.resource('dynamodb') table = dynamodb.Table('MyTable') # Function to update item def update_item(item_id, expected_value): response = table.update_item( Key={ 'PK': item_id, }, UpdateExpression='SET counter = counter + :inc', ConditionExpression='counter = :expected', ExpressionAttributeValues={ ':inc': 1, ':expected': expected_value }, ReturnValues='UPDATED_NEW' ) return response # Attempting to update the item try: result = update_item('item123', 2) print('Update successful:', result) except Exception as e: print('behavior updating item:', str(e)) ``` I've verified that the item with PK 'item123' exists and its current counter value is 2. Despite this, the Lambda function throws the following behavior: `behavior updating item: An behavior occurred (ConditionalCheckFailedException) when calling the UpdateItem operation: The conditional request failed`. I've double-checked the expected value I'm passing in and confirmed it matches the current value in DynamoDB. Additionally, I’ve added logging to ensure that the function is accessing the correct item. Is there something I'm missing in my condition expression, or could it be related to eventual consistency in DynamoDB? Any insights or suggestions would be greatly appreciated. This is part of a larger CLI tool I'm building. What am I doing wrong? For context: I'm using Python on Windows. Am I missing something obvious? For context: I'm using Python on Windows 11.