[Solved] A resolver mapping template for a DynamoDB Query operation uses this snippet:{"version": "2018-05-29", "operation": "Query", "query": {"expression": "#pk = :pk", "expressionNames": {"#pk":... | DynamoDB

DynamoDB - with Serverless

A resolver mapping template for a DynamoDB Query operation uses this snippet:

{"version": "2018-05-29", "operation": "Query", "query": {"expression": "#pk = :pk", "expressionNames": {"#pk": "partitionKey"}, "expressionValues": {":pk": "$ctx.args.pk"}}}

Why does this cause a runtime error?

AExpression values must be wrapped with DynamoDB types like {"S": "value"}

BThe operation "Query" is not valid for DynamoDB in AppSync

CExpression names cannot use # symbol

DPartition key attribute name must be "id"

Step-by-Step Solution

Solution:

Step 1: Review expressionValues format
Expression values in DynamoDB VTL must specify data types, e.g., {"S": "value"} for strings.
Step 2: Identify missing type wrappers
The snippet uses ":pk": "$ctx.args.pk" without wrapping in DynamoDB type, causing error.
Final Answer:
Expression values must be wrapped with DynamoDB types like {"S": "value"} -> Option A
Quick Check:
Expression values need type wrappers = D [OK]

Quick Trick: Wrap expression values with DynamoDB types in queries [OK]

Common Mistakes:

MISTAKES

Omitting type wrappers in expressionValues
Misusing operation names
Incorrect attribute naming assumptions

Master "with Serverless" in DynamoDB

9 interactive learning modes - each teaches the same concept differently

Learn Why Deep Visual Try Challenge Project Recall Time

More DynamoDB Quizzes

A resolver mapping template for a DynamoDB Query operation uses this snippet:

Step 1: Review expressionValues format

Step 2: Identify missing type wrappers

Final Answer:

Quick Check:

Want More Practice?