Element Builder - How to Add Custom Fields to Response Header

In some cases, you'll need to add custom fields to a response header. This is achieved by creating a PostRequest Hook on the resource and using the option "response_headers".

Let's say you have a vendor response body that contains a collection of results and an offset field like so:

{ 
  "hasMore": true, 
  "offset": 2,  
  "total": 2477, 
  "results": [ 
    {...},{...},{...} 
  ]
}

and you want to return the "results" as the response body but want to preserve the offset for paging purposes. You would set the "root key" to "results" and add the offset field to the response header. The PostRequest Hook should look something like this:

if(!response_headers || response_iserror) {
 done();
} else {
 let headers = {};
 headers['offset'] = response_body["offset"];
 done({'response_headers': headers})
}

The offset field is added to the header along with Cloud Elements' default header fields.