how to add a status message on a grails respond - grails

Question

I have created a method that is called after every uncatched exception and respond a gson view:
void handleError(){
respond([status: 500, view: "/customErr"], [
code : 500,
message : "whatever internal error",
])
}
this works fine but the main problem that I have is that my client (another server acting as client) is receiving a http response with a 500 status but the status message is null. I've checked the respond docs and I don't see a property message or something.
this if what my client receive:
wslite.rest.RESTClientException: 500 null
and that null is the response's status message that is not set by grails
How can I add a detail message on my respond? idyllically something like this:
respond([status: 500, statusMessage: "my custom
message", view: "/customErr"], [
code : 500,
message : "whatever internal error",
])

Answer 1

grails uses Servlet API’s HttpServletResponse to build response.
now check the java doc for HttpServletResponse class.
there are only 2 methods to define status message:
void setStatus(int sc, String msg) Deprecated. As of version 2.1, due to ambiguous meaning of the message parameter. To set a status code use setStatus(int), to send an error with a description use sendError(int, String).
void sendError(int sc, String msg) Sends an error response to the client using the specified status and clears the buffer. The server defaults to creating the response to look like an HTML-formatted server error page containing the specified message, setting the content type to "text/html".
The first one is deprecated. The second one sends the status message, but it will not send the body - mainly this used for fatal errors...
So, officially by servlet documentation there is no way to send both: message and body in response.
The question is tricky. Because according to Apache Tomcat the "custom status message" feature will be removed starting from version 9: https://tomcat.apache.org/tomcat-8.5-doc/config/systemprops.html#Other
But according to RFC2616 sec 6.1.1 : The reason phrases listed here are only recommendations -- they MAY be replaced by local equivalents without affecting the protocol.

Answer 2

This doesn't directly answer your question, and may not solve your issue depending on how much control you have over the application that receives the error, but you can add error messages to the header of the response which should pass through to the client (if it knows to check for them).
String errorMessage = "Whatever Internal Server Error"
response.addHeader("custom-error", errorMessage)
response.sendError(500, errorMessage)
That'll send the message in the header and as the response message... I do not know if this works with respond() or how that interacts with the response object in the controller... but if you're responding to render a view as the error page, you should be able to add the message to the model included in the respond() call and show that on the error page (at least, I'd think so).