Q:

How to set a custom error message on springmvc @RequestParam date

I have a method on a rest service defined like this:
    public ResponseEntity<?> methodName(@RequestParam("date") @DateTimeFormat(pattern = "yyyy-MM-dd") Date date,

)
When the date parameter is set to an invalid date such as 2020-3-999, the response from the service is:

{
      "status": "error",
      "message": "Malformed request" }

I need a way to customize what appears in the "message" field of this return message..

A:

You can create a Custom Error Handling class which should be annotated with @ControllerAdvice and extend ResponseEntityExceptionHandler. 
Inside the class you can handle the exception that is occurred in your scenario and respond with a custom Error message. 
Refer to https://www.baeldung.com/global-error-handler-in-a-spring-rest-api for implementation details. 

