[jira] [Created] (WICKET-6499) Support for Bean Validation 2.0

[Thomas Heigl (JIRA)]

Thomas Heigl created WICKET-6499:
------------------------------------

             Summary: Support for Bean Validation 2.0
                 Key: WICKET-6499
                 URL: https://issues.apache.org/jira/browse/WICKET-6499
             Project: Wicket
          Issue Type: Improvement
          Components: wicket-bean-validation
            Reporter: Thomas Heigl


Bean Validation 2.0 and the reference implementation Hibernate Validator 6.0 
were [recently released|http://beanvalidation.org/2.0/].

I upgraded my application and discovered that fields annotated with 
{{@NotEmpty}} and {{@NotBlank}} are not automatically marked as required 
anymore.

So I started to investigate.

h4. Bean Validation 1.x

Wicket {{PropertyValidator}} marks form components as required if it encounters 
the {{@NotNull}} annotation on field:

{code}
boolean isRequired()
        {
                List<NotNull> constraints = findNotNullConstraints();
                for (NotNull constraint : constraints)
                {
                        ...
                }
                return false;
        }
{code}

In Bean Validation 1.x, this lookup returns not only properties annotated with 
- {{@javax.validation.constraints.NotNull}}

but also properties annotated with  
- {{@org.hibernate.validator.constraints.NotEmpty}} 
- {{@org.hibernate.validator.constraints.NotBlank}} 

because these annotations are implemented as composed constraints:

{code}
@NotNull
@Deprecated
public @interface NotEmpty {}
{code}

{code}
@NotNull
@Deprecated
public @interface NotBlank {}
{code}

h4. Bean Validation 2.x

Both annotations are now deprecated and replaced with "official" versions: 
- {{javax.validation.constraints.NotEmpty}}
- {{javax.validation.constraints.NotBlank}}

The new annotations are *not* implemented as composed constraints, and thus do 
*not* contain the {{@NotNull}} annotation.

I asked about the rationale and the recommended solution on the [HV 
forum|https://forum.hibernate.org/viewtopic.php?f=9&t=1044998&start=0] and got 
the following reply from the Hibernate Team:

{quote}
When promoting @NotEmpty and @NotBlank from HV to the Bean Validation spec we 
decided to define them as composed constraints (as their previous 
counterparts), but instead leave this as an implementation detail to BV 
providers. The reason being, that the implementation can be more efficient when 
using a single constraint validator instead of relying on constraint 
composition.

So you'd indeed have to expand your scan to look for @NotNull, @NotEmpty and 
@NotBlank.
{quote}

I suggest that {{PropertyValidator}} should scan for these new annotations when 
Bean Validation 2.0 is on the classpath.



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