Spring: Validate specific model attributes

Apply @InitBinder to specific commands

Validators will not be called unless your parameter has a @Valid annotation.

By default initBinder method will be invoked for every parameter (model attributes).

@InitBinder has an optional attribute where you can specify the specific attribute(s) to apply the method.

Te value of @InitBinder can be one of the following:

• name of a model attribute;
• name of a request parameter;
• name of the class of parameter can be used, but starting with a small letter. That's how Spring exposes unnamed attributes to the model.

### Prevent *"IllegalStateException: Invalid target for Validator"* error Assume that among the other requests, you've added the `UserDTO`: model.addAttribute(USER_ATTR, UserConverter.toDto(persistedUser)); As result `initBinder` method will be applied to `UserDTO` and u'll receive an exception: java.lang.IllegalStateException: Invalid target for Validator It happened, because your `NoteValidator` doesn't support `UserDTO` class. So, to avoid an exception we have to apply `initBinder` only to `UserDTO` class. Here is our create note method: @RequestMapping(method = RequestMethod.POST) @ResponseBody public OperationResponseDto createNote(@Valid @RequestBody NoteDTO stream, BindingResult result, Principal principal) { if (result.hasErrors()) { return OperationResponseDto.getErrorResponse(result.getFieldErrors()); } else { /*...*/ } } Apply `initBinder` method only to `NoteDTO` class: @InitBinder("noteDTO") public void initBinder(final WebDataBinder binder) { binder.registerCustomEditor(DomainValueDTO.class, "supportedPlatforms", notePropetyEditor); binder.addValidators(noteValidator); } ---- ## see Also * [Spring DOCS - InitBinder](http://docs.spring.io/autorepo/docs/spring/4.0.6.RELEASE/javadoc-api/org/springframework/web/bind/annotation/InitBinder.html) * [Spring DOCS](http://docs.spring.io/spring/docs/current/spring-framework-reference/htmlsingle/) * [Tutorials Point - Best Practices](http://www.tutorialspoint.com/developers_best_practices/) * [Keynote: Top JS frmeworks 2015](http://bloomlab.blogspot.com.ee/2015/03/top-javascript-frameworks-2015.html)