How to output meaningful errors in aura server side calls?

Question

I am attempting to use exceptions to display errors in my aura application. As per documentation, the only way to return a meaningful error from code is to throw AuraHandledException. The problem is that the class is not extensible (non-virtual) meaning that only a custom message property is returned as part of the exception. Is there a way to use some other exception class that can be extended to include more attributes and that would be handled in the same way AuraHandledException is?

Answer 1

I ended up JSON-encoding the message for AuraHandledException and attempting to parse the JSON inside the javascript callback. If parsing fails, I assume the message is a string and use it instead. This allows me to pass any structured error response that I need now or in the future. Not saying that it is the right way to do things but I don't see an alternative at the moment.

Answer 2

AuraHandledException is a quick way to tell the client to throw an error and display your custom message, gracefully. If you want to "handle" the error on the client, then you should do so by catching the exception on the server and returning your custom result with more information as to how the client should behave:

var state = response.getState();
if (state === "SUCCESS") {

  var response = response.getResponseValue();

  if(response.hasError) {
    switch(response.errorCode) {
      case 403: throw new Error("You don't have permission"); break;

      // bad request eg. bad parameters sent to server
      case 400: helper.showInlineErrorMessageInForm(); break;
    }
  }
  else {
    helperProcessSuccess();
  }
}