Spring MVC - HTTP status code 400 (Bad Request) for missing field which is defined as being not required
spring, spring-annotations, spring-mvc
Solution
I came across the same situation, and this happens when your parameter is present in the request with an empty value.
That is, if your POST body contains "number=" (with empty value), then Spring throws this exception. However, if the parameter is not present at all in the request, it should work without any errors.
Problem
I have Spring MVC application with this controller method. ``` @RequestMapping(value = "/add", method = RequestMethod.POST) public String addNumber(@RequestParam(value="number", required=false) Long number) { ... return "redirect:/showAll/"; } ``` In my JSP I have a standard HTML form which is posting a value named "number" to the controller method above. However, if I leave out the value (do not enter anything into the text field) and POST the data to the controller, before the controller method is called my browser shows ``` HTTP Status 400 - Required Long parameter 'number' is not present ``` although the controller method annotation clearly defines the "number"-parameter as not required. Does anyone have a slight idea of what could be going on? Thank you. PS: The exception that is being thrown is as follows: ``` org.springframework.web.bind.MissingServletRequestParameterException: Required Long parameter 'number' is not present ``` EDIT: This is a Spring 3.2.3.RELEASE bug ( see here). With version 3.1.4.RELEASE I do not have this problem anymore.