AWS API Gateway Header and Body Mappings in Integration Response

Question

I am trying to properly setup Body Mapping and Header Mapping in the Integration Response for an API Gateway endpoint.

In our Lambda we have

if (response.statusCode == 200) {
    context.succeed(output);
} else if (response.statusCode == 206) {
    var paginationObject = {
        errorType : "PartialContent",
        errorCode : 206,
        detailedMessage : "PartialContent Returned",
        stackTrace : [],
        data : {
               output
        }
    };

    context.fail(JSON.stringify(paginationObject));
}

I then handle fetching this in the Integration Response using a Lambda Error Regex of .*PartialContent.* and have my Body Mapping Template as

#set($allParams = $input.params())
#set($body = $util.parseJson($input.json('$.errorMessage')))

$body

This gives me the correct HTTP status code and JSON output, but it has too much data in the body. The response looks like:

{
  "errorType":"PartialContent",
  "errorCode":206,
  "detailedMessage":"PartialContent Returned",
  "stackTrace":[],
  "data":{
    "output":{
      "status":206,
      "bodyJson":[{"call_date":"2017-08-19 18:17:21"}],
      "headers":{"date":"Thu, 02 Nov 2017 18:36:52 GMT",
                 "server":"Apache",
                 "x-pagination-page-size":10}
    }
  }
}

I want the headers to actually appear as headers in the response, and I want the body to just be the content inside of bodyJson

I've tried to change the body mapping template to use $body.data.output.bodyJson, but when I do that the body is completely empty. I've also got the headers set in the Header Mappers, trying both integration.response.body.headers.x-pagination-page-size and integration.response.header.x-pagination-page-size but both times the header is blank, even though I can see the proper values in the JSON output.

How do I get just the bodyJson element to be output as the body of the response? And how do I properly get the headers mapped?

Answer 1

Did you try to use Lambda Error Regex in Integration Response? For example:

.*"status":400.*

body mapping templetes:

#set ($errorMessageObj = $util.parseJson($input.path('$.errorMessage')))
{
  "status" : "$errorMessageObj.status",
  "errorType" : "$errorMessageObj.errorType",
  "message" : "$errorMessageObj.errorMessage"
}

I created an error function in my Lamda:

function error(status, errorType, errorMessage, callback){
    callback(JSON.stringify({
        status: status,
        errorType: errorType,
        errorMessage: errorMessage
    }));
}

usage:

error(404, "Not Found", "Resource is not found", callback);