How to use Hal+Json with AWS AppSync

Question

My backend resturns json using the media type hal+json(rest api). The problem here is that velocity resolver of AWS AppSync returns:

Lexical error, Encountered: \"_\" (95), after:\".\" at unset[line 8, column 28]"

Because the media type node starts with a underscore, example:

{  
     "_embedded":{  
         "vehicle-assemblers":[...]
     }
}

I believe the engine that AppSync uses is complaining about a variable starting with underscore.

"Configure the request mapping template" (AWS Edit Resolver)

 ## Raise a GraphQL field error in case of a datasource
 #if($ctx.error)
   $util.error($ctx.error.message, $ctx.error.type)
 #end
 ## If the response is not 200 then return an error.
 #if($ctx.result.statusCode == 200)
    #set($response = $util.parseJson($ctx.result.body))  
    $util.toJson($response._embedded.vehicle-assemblers) ##line 8  
 #else
    $utils.appendError($ctx.result.body, $ctx.result.statusCode)
 #end

Has anyone any idea how to solve this problem?

score 1 · Answer 1 · answered Jan 14 '19 at 10:17

I was able to solve

#if($ctx.error)
  $util.error($ctx.error.message, $ctx.error.type)
#end

#if($ctx.result.statusCode == 200)
    #set($response = $util.parseJson($ctx.result.body))
    #set($vehicles = $util.toJson($response["_embedded"]["vehicle-assemblers"]))
    {
      "items": $vehicles  
    }    
#else
    $utils.appendError($ctx.result.body, $ctx.result.statusCode)
#end

How to use Hal+Json with AWS AppSync

1 Answers1