BindingResult errors from @ModelAttribute are not carried over to @RequestMapping annotated method [SPR-11722]

[spring-projects-issues]

Vladimir Semenov opened SPR-11722 and commented

BindingResult errors generated in @ModelAttribute annotated method are not carried over into the BindingResult passed to @RequestMapping annotated method in the same controller.

This appears to be a bug since @ModelAttribute annotated method accepts BindingResult, and errors in Model from @ModelAttribute annotated method are carried over to @RequestMapping annotated method, but errors from BindingResult are not.

---

Affects: 3.1 GA

[spring-projects-issues]

Rossen Stoyanchev commented

BindingResult errors generated in @ModelAttribute annotated method

I'm not sure what you mean here. Model attribute methods are used to add attributes to the model. Actual binding and validation of command objects is in the @RequestMapping method. Can you show an example snippet of code?

[spring-projects-issues]

Vladimir Semenov commented

Here is an example illustrating what I meant:

@Controller
@RequestMapping("/example")
public class ExampleController {

	@ModelAttribute
	public void modelAttributeMethod(
			Model model,
			@ModelAttribute Command command, 
			BindingResult errors) {
		
		errors.reject("model.attribute.error");
		
		// Error is now available in the model under org.springframework.validation.BindingResult.command attribute name.
	}

	@RequestMapping(method = RequestMethod.POST)
	public String requestMappingMethod(
			Model model,
			@ModelAttribute Command command,
			BindingResult errors) {

		// BindingResult errors is empty despite errors.reject(..) having been called in modelAttributeMethod(..)
		
		// Model model no longer contains the errors under org.springframework.validation.BindingResult.command attribute name.
		
		// Since @ModelAttribute annotated method accepts BeanPropertyBindingResult and BindingAwareModelMap, I would expect
		// that errors from modelAttributeMethod(..) get carried over to requestMappingMethod(..)

		return "view";
	}
}

[spring-projects-issues]

Rossen Stoyanchev commented

Thanks for the extra detail. What is your intent actually?

The above example causes binding and validation on the command object twice -- once at the @MA method and a second at the @RM method. Furthermore the @MA is invoked before every @RM method of the controller. So it this looks rather unusual even if possible.

[spring-projects-issues]

Rossen Stoyanchev commented

Actually I should qualify "even if possible". We've never supported this style explicitly so while it is not failing with an exception of any kind, I am not surprised the BindingResult from the @MA method isn't carried over to the @RM method.

[spring-projects-issues]

Vladimir Semenov commented

Our use case for it is to provide default CAPTCHA and IP throttling implementation that gets invoked prior to @RM methods. That requires access to Model, Command, Request and BindingResult. Right now we have a workaround that passes BindingResult in request context to @InitBinder, which prepares BindingResult for @RM method, but being able to do this with just @MA method would be much cleaner.

[spring-projects-issues]

Rossen Stoyanchev commented

I see, well this really isn't meant to be used this way. Data binding and validation for the command object happen at the @RequestMapping method, not earlier.

Can you invoke it after the @RequestMapping method, e.g. from a HandlerInterceptor.postHandle? Or you could also invoke it from inside your @RequestMapping method where you would also need to deal with bindingResult.hasErrors().

This may also be related to #15486 so I look forward to you comment, thanks.