Question

Dear Spring community,

What I am trying to implement is the following:

• I would like to have a custom validator per controller (via @InitBinder)
• I would like Spring to call validator.validate() (so not this way)
• I would like to use JSR-303 @Valid annotation for that
• The bean to be validated (RegistrationForm) does not have any per-field JSR-303 annotations
• I don’t want to include validation implementation (like Hibernate) into classpath; it will be useless as from above statement

I basically follow the steps mentioned here:

• I add javax.validation.validation-api:validation-api as my dependency
• I use <mvc:annotation-driven />
• I mark my model with @Valid:
  public String onRegistrationFormSubmitted(@ModelAttribute("registrationForm") @Valid RegistrationForm registrationForm, BindingResult result) ...

So what happens, is that validation API tries to locate any implementation and fails:

Caused by: javax.validation.ValidationException: Unable to find a default provider
    at javax.validation.Validation$GenericBootstrapImpl.configure(Validation.java:264)
    at org.springframework.validation.beanvalidation.LocalValidatorFactoryBean.afterPropertiesSet(LocalValidatorFactoryBean.java:183)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1477)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1417)

The way out is to define a validator property for AnnotationDrivenBeanDefinitionParser:

<bean name="validator" class="org.company.module.RegistrationFormValidator" />

<mvc:annotation-driven validator="validator" />

but this approach means that the validator will be set to all controllers by ConfigurableWebBindingInitializer.initBinder().

I understand that I am trying to use the framework in a special way, but what the community will say, if there is a special meaning for validator property which tells that validator does not need to be resolved, e.g.

<mvc:annotation-driven validator="manual" />

with special treatment:

--- AnnotationDrivenBeanDefinitionParser.java.orig      2011-06-30 14:33:10.287577300 +0200
+++ AnnotationDrivenBeanDefinitionParser.java   2011-06-30 14:34:27.897449000 +0200
@@ -152,6 +152,10 @@

        private RuntimeBeanReference getValidator(Element element, Object source, ParserContext parserContext) {
                if (element.hasAttribute("validator")) {
+                       if ("manual".equals(element.getAttribute("validator"))) {
+                               return null;
+                       }
+
                        return new RuntimeBeanReference(element.getAttribute("validator"));
                }
                else if (jsr303Present) {

Any feedback is welcomed.

P.S. Repost from Spring Forum.

Answer 1

This is also a repost of my answer/workaround on the above mentioned forum. Anyway I think it might help having it here as well.

The only workaround I found was to implement my own @Valid annotation, once Spring (at least in 3.1.1.RELEASE code base) only checks the method argument annotation’s simple name (please look into the org.springframework.web.method.annotation.ModelAttributeMethodProcessor class below). This way, I don’t need to add javax.validation.validation-api:validation-api to my project’s dependencies and I stop getting the infamous javax.validation.ValidationException: Unable to find a default provider.

/**
 * Validate the model attribute if applicable.
 * <p>The default implementation checks for {@code @javax.validation.Valid}.
 * @param binder the DataBinder to be used
 * @param parameter the method parameter
 */
protected void validateIfApplicable(WebDataBinder binder, MethodParameter parameter) {
    Annotation[] annotations = parameter.getParameterAnnotations();
    for (Annotation annot : annotations) {
        if (annot.annotationType().getSimpleName().startsWith("Valid")) {
            Object hints = AnnotationUtils.getValue(annot);
            binder.validate(hints instanceof Object[] ? (Object[]) hints : new Object[] {hints});
        }
    }
}