I have been integrating express step functions to API Gateway endpoints and have run into an issue where I am returning following object

{
  "statusCode":"500",
  "body":{
    "message: "Internal Server Error"
   }
}

OR

{
  "statusCode": "200",
  "body": {
    "result": {...}
  }
}

I want to be able to map the statusCode to HTTP status and the body to HTTP response body. I have been able to map the statusCode to the HTTP status as follows,

##velocity template

#set($inputRoot=$input.path('$'))

#set($output=$util.parseJson($inputRoot.output))

#set($context.responseOverride.status=$output.statusCode)

this works but when I try to return the body, what I get in response (in Postman) is:

{message=Internal Server Error
}

I have been integrating express step functions to API Gateway endpoints and have run into an issue where I am returning following object

{
  "statusCode":"500",
  "body":{
    "message: "Internal Server Error"
   }
}

OR

{
  "statusCode": "200",
  "body": {
    "result": {...}
  }
}

I want to be able to map the statusCode to HTTP status and the body to HTTP response body. I have been able to map the statusCode to the HTTP status as follows,

##velocity template

#set($inputRoot=$input.path('$'))

#set($output=$util.parseJson($inputRoot.output))

#set($context.responseOverride.status=$output.statusCode)

this works but when I try to return the body, what I get in response (in Postman) is:

{message=Internal Server Error
}

• amazon-web-services
• velocity
• gateway

• What specific body output are you aiming to achieve? Based on the description, it seems the body already meets your requirements. – Gerard Haw Commented Nov 16, 2024 at 4:24
• I want it in Json format. { "message": "Internal Server Error" }, as of now I am getting message=..., – Pratik Commented Nov 16, 2024 at 21:21
• Basically I want to map Body as is to Http Response Body – Pratik Commented Nov 16, 2024 at 21:23
• Can you provide some API Gateway logs? – fa44 Commented Nov 19, 2024 at 21:33

1 Answer 1

The issue is that you have parsed the json in the template, what you want is:

##velocity template

#set($output=$input.json('$.output'))

#set($context.responseOverride.status=$input.path('$.output.statusCode')

https://docs.aws.amazon/apigateway/latest/developerguide/api-gateway-mapping-template-reference.html#input-variable-reference

The .json function of the input object will convert it to a json string istead of an object internally in VTL