forwarding this email to hibernate-dev to get some more feedback.
Here are some of my thoughts. The method level validation is suggested in
Appendix C of the Bean Validation specification. The method signatures
there all return a set of ConstraintViolations.
The question is how binding these signatures are.
Root bean and property path are indeed questionable for method level
validation. By extending ConstraintViolation you still have to deal with
these values. Maybe instead of
extending we should have a new interface MethodConstraintViolation.
Emmanuel, do you have some more feedback on what was discussed regarding
------- Forwarded message -------
From: "Gunnar Morling" <gunnar.morling(a)googlemail.com>
To: "Hardy Ferentschik" <hibernate(a)ferentschik.de>
while working on method-level validation I wondered how to represent the
failing validation of method parameters. I think
javax.validation.ConstraintViolation in its current form is only partly
suitable for the needs of parameter/return value validation:
* The concept of property path seems not to fit right. How would the
property path look for a failing parameter constraint? One could come up
with something like "MyBean.MyMethod(String,Int).Parameters" but I
can't say I'd like that
* The concept of a root bean does only fit partly. I think one would need
a safe reference to the "root method" and the parameter index. A direct
reference to the class hosting the validated method seems only partly
useful (and could anytimes be retrieved from a Method reference).
I therefore prototyped this into this direction:
* Created a MethodConstraintViolation that extends ConstraintViolation by
adding fields the causing method and the parameter index (one surely would
add a flag or something in case of return value validation)
* In case a constraint directly at one of a method's parameters fail,
ConstraintViolation#rootBean and propertyPath are null (but method and
parameterIndex are set)
* In case a "cascading" constraint fails (meaning in this context, a
parameter is annotated with @Valid and the referenced bean has constraints
itself which in turn fail), method and parameterIndex are set, rootBean
and propertyPath refer to parameter bean itself, *not* the class hosting
the validated method
WDYT, is this the right way to go? Maybe we should brainstorm a bit on IRC?