Which of the following templates correctly implements this logic?
hard📝 Application Q9 of 15
AWS - API Gateway
You have a response mapping template that needs to conditionally include an error field only if the backend response contains an error message. Which of the following templates correctly implements this logic?
D#if($input.path('$.errorMessage') == null)
{"error": "No error"}
#end
Step-by-Step Solution
Solution:
Step 1: Understand conditional logic in templates
Use #if directive to check if errorMessage exists before including error field.
Step 2: Evaluate options
#if($input.path('$.errorMessage'))
{"error": "$input.path('$.errorMessage')"}
#else
{}
#end includes error only if errorMessage exists. The simple JSON object always includes error (null if missing). The #set version always includes error even if null. The null-check version includes error only when missing, with wrong message.
Final Answer:
#if($input.path('$.errorMessage'))
{"error": "$input.path('$.errorMessage')"}
#else
{}
#end -> Option A
Quick Check:
Use #if to conditionally include fields [OK]
Quick Trick:Use #if to include fields only when data exists [OK]
Common Mistakes:
MISTAKES
Always including error field regardless of data
Misusing #set without condition
Incorrect null checks
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