I have a simple class that has one of its properties as a String array. As per this document, using @Valid on an array, collection etc. will recursively validate each element of the array/collection.
@Valid
@Pattern(regexp="^[_ A-Za-z0-9]+$")
public String[] defaultAppAdminRoles;
the above annotation on the property generates the following exception:
Exception in thread "main" javax.validation.UnexpectedTypeException: No validator could be found for type java.lang.String[]. See: @Pattern at public java.lang.String[] com.hm.vigil.platform.ops.model.Application.defaultAppAdminRoles
at org.apache.bval.jsr303.AnnotationProcessor.checkOneType(AnnotationProcessor.java:326)
at org.apache.bval.jsr303.AnnotationProcessor.getConstraintValidator(AnnotationProcessor.java:301)
at org.apache.bval.jsr303.AnnotationProcessor.applyConstraint(AnnotationProcessor.java:241)
at org.apache.bval.jsr303.AnnotationProcessor.processAnnotation(AnnotationProcessor.java:149)
at org.apache.bval.jsr303.AnnotationProcessor.processAnnotations(AnnotationProcessor.java:90)
at org.apache.bval.jsr303.Jsr303MetaBeanFactory.processClass(Jsr303MetaBeanFactory.java:134)
at org.apache.bval.jsr303.Jsr303MetaBeanFactory.buildMetaBean(Jsr303MetaBeanFactory.java:95)
at org.apache.bval.MetaBeanBuilder.buildForClass(MetaBeanBuilder.java:131)
at org.apache.bval.MetaBeanManager.findForClass(MetaBeanManager.java:102)
at org.apache.bval.jsr303.ClassValidator.validate(ClassValidator.java:140)
at com.hm.vigil.platform.commons.AbstractValidatable.isValid(AbstractValidatable.java:33)
at com.hm.vigil.platform.ops.model.Application.main(Application.java:54)
I am using Apache BVal as validation provider.
The question, is the above method correct?
If it is not correct, what is the correct way to validate an array/collection with bean validation?
If it is correct, then is it some limitation of Apache BVal?
By adding the @Valid annotation like you've done, the validation algorithm is applied on each element (validation of the element constraints).
In your case the String class has no constraints. The @Pattern constraint you've added is applied to the array and not on each element of it. Since @Pattern constraint cannot be applied on a array, you are getting an error message.
You can create a custom validation constraint for your array (see Hibernate docs for more info) or you can use a wrapper class like @Jordi Castilla mentioned.