optional POST parameter in spring MVC?

Question

I have the following code:

@RequestMapping(method = RequestMethod.POST) public ModelAndView editItem(String name, String description) 

However, sometime description is not passed in (this is a simplified example than the real one), and i would like to make description optional, perhaps by filling in a default value if none is passed in.

Anyone have any idea how to do that?

thanks a lot!

Jason

Answer 1

If you are using Spring MVC 3.0 or higher then just set defaultValue parameter of @RequestParam:

public ModelAndView editItem(@RequestParam(value = "description", defaultValue = "new value") String description) 

In Spring MVC 2.5, I suggest to mark value as required = false and check their value against null manually:

public ModelAndView editItem(@RequestParam(value = "description", required = false) String description) {     if (description == null) {         description = "new value";     }     ... } 

See also corresponding documentation about @RequestParam annotation.

---

UPDATE for JDK 8 & Spring 4.1+: now you could use java.util.Optional like this:

public ModelAndView editItem(@RequestParam("description") Optional<String> description) {      item.setDescription(description.getOrElse("default value"));      // or only if it's present:     description.ifPresent(value -> item.setDescription(description));     ... } 

Answer 2

Instead of using @RequestParam for the optional parameters, take a parameter of type org.springframework.web.context.request.WebRequest. For example,

@RequestMapping(method = RequestMethod.POST) public ModelAndView editItem(   @RequestParam("name")String name,   org.springframework.web.context.request.WebRequest webRequest) {   String description = webRequest.getParameter("description");    if (description  != null)   {      // optional parameter is present   }   else   {     // optional parameter is not there.   } } 

Note: See below (defaultValue and required) for a way to solve this without using a WebRequest parameter.