peech peech - 5 months ago 60
Java Question

Java Spring - how to handle missing required request parameters

Consider the following mapping:

@RequestMapping(value = "/superDuperPage", method = RequestMethod.GET)
public String superDuperPage(@RequestParam(value = "someParameter", required = true) String parameter)
{
return "somePage";
}


I want to handle missing parameter case by not changing to
required = false
. By default
400
error is returned, but I want to return let's say a different page. How to I achieve this?

Answer

If a required @RequestParam is not present in the request, Spring will throw a MissingServletRequestParameterException exception. You can define an @ExceptionHandler in the same controller or in a @ControllerAdvice to handle that exception:

@ExceptionHandler(MissingServletRequestParameterException.class)
public void handleMissingParams(MissingServletRequestParameterException ex) {
    String name = ex.getParameterName();
    System.out.println(name + " parameter is missing");
    // Actual exception handling
}

I want to return let's say a different page. How to I achieve this?

As the Spring documentation states:

Much like standard controller methods annotated with a @RequestMapping annotation, the method arguments and return values of @ExceptionHandler methods can be flexible. For example, the HttpServletRequest can be accessed in Servlet environments and the PortletRequest in Portlet environments. The return type can be a String, which is interpreted as a view name, a ModelAndView object, a ResponseEntity, or you can also add the @ResponseBody to have the method return value converted with message converters and written to the response stream.

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