The JSR 303 bean validation, The extended ConstraintValidator cannot use the CDI

问题

I've tried to learn the JSF 2.0 with bean validation at the class level as the following: -

The utility

@Singleton
public class MyUtility {
    public boolean isValid(final String input) {
       return (input != null) || (!input.trim().equals(""));
    }
}

The constraint annotation

@Retention(RetentionPolicy.RUNTIME)
@Target({
    ElementType.TYPE,
    ElementType.ANNOTATION_TYPE,
    ElementType.FIELD
    })
@Constraint(validatedBy = Validator.class)
@Documented
public @interface Validatable {
    String  message() default "Validation is failure";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}

The constraint validator

public class Validator extends ConstraintValidator<Validatable, MyBean> {
    //
    //----> Try to inject the utility, but it cannot as null.
    //
    @Inject
    private MyUtility myUtil;

    public void initialize(ValidatableconstraintAnnotation) {
        //nothing
    }

    public boolean isValid(final MyBean myBean, 
                           final ConstraintValidatorContext constraintContext) {

        if (myBean == null) {
            return true;
        }
        //
        //----> Null pointer exception here.
        //
        return this.myUtil.isValid(myBean.getName());
    }
}

The data bean

@Validatable
public class MyBean {
    private String name;
    //Getter and Setter here
}

The JSF backing bean

@Named
@SessionScoped
public class Page1 {
    //javax.validation.Validator
    @Inject
    private Validator validator;

    @Inject
    private MyBean myBean;

    //Submit method
    public void submit() {
        Set<ConstraintViolation<Object>> violations = 
                         this.validator.validate(this.myBean);
        if (violations.size() > 0) {
            //Handle error here.
        }
    }
}

After running I've faced the exception as java.lang.NullPointerException at the class named "Validator" at the line return this.myUtil.isValid(myBean.getName());. I understand that the CDI does not inject my utility instance. Please correct me If I'm wrong.

I'm not sure if I'm doing something wrong or it is a bean validation limitation. Could you please help to explain further?

回答1:

Your right, Hibernate Constraint Validator is not registered as a CDI-Bean by default (and though cannot receive dependencies).

Just put the Seam-Validation module on your classpath, and everything should run fine.

BTW: studying the source-code of the module is an excellent example of the elegance and simplicity of CDI extension. It's doesn't need more than a few dozens lines of code to bridge from CDI to hibernate validations...

来源：https://stackoverflow.com/questions/10100439/the-jsr-303-bean-validation-the-extended-constraintvalidator-cannot-use-the-cdi

标签

jsf-2

cdi

bean-validation