You want to implement a GraphQL mutation in AppSync that updates a user's email only if the user exists in DynamoDB. Which resolver operation and condition should you use in the mapping template?

hard🚀 Application Q8 of 15

DynamoDB - with Serverless

AUse UpdateItem operation with a condition expression checking attribute_exists(id)

BUse PutItem operation without any condition expression

CUse DeleteItem operation with a condition expression checking attribute_not_exists(email)

DUse Query operation with a filter expression on email

Step-by-Step Solution

Solution:

Step 1: Choose operation to update existing item
UpdateItem modifies attributes of an existing item and supports condition expressions.
Step 2: Use condition to ensure item exists
Condition expression attribute_exists(id) ensures update only if user exists.
Final Answer:
UpdateItem with condition expression attribute_exists(id) -> Option A
Quick Check:
Update with condition to check existence = B [OK]

Quick Trick: Use UpdateItem with attribute_exists condition to update safely [OK]

Common Mistakes:

MISTAKES

Using PutItem which overwrites without condition
Using DeleteItem incorrectly
Using Query instead of update operation

Master "with Serverless" in DynamoDB

9 interactive learning modes - each teaches the same concept differently

Learn Why Deep Visual Try Challenge Project Recall Time

Want More Practice?

15+ quiz questions · All difficulty levels · Free

Free Signup - Practice All Questions

More DynamoDB Quizzes

You want to implement a GraphQL mutation in AppSync that updates a user's email only if the user exists in DynamoDB. Which resolver operation and condition should you use in the mapping template?

Step 1: Choose operation to update existing item

Step 2: Use condition to ensure item exists

Final Answer:

Quick Check:

Want More Practice?