Re: [bv-dev] Distinguishing cross-parameter and generic constraints

2013/1/14 Emmanuel Bernard <emmanuel(a)hibernate.org&gt; After letting this idea rest for a while, I still like it. In the issue, you also proposed to go a step further and get rid of @CrossParameterConstraint altogether. I sort of remember not being keen on the idea to protect future evolutions on the type-safe cross-parameter way. Have you thought about it more? What is your opinion? Yes, I still like the idea of having only the @Constraint annotation for defining constraints, but one problem I see is that one can not specify different validators for return value arrays and method argument arrays in cases like this: @MyCustomConstraint(validationAppliesTo = PARAMETERS) public void foo(int p1, int p2) { ... } @MyCustomConstraint(validationAppliesTo = ANNOTATED_ELEMENT) public Object[] bar() { ... } With the different annotations @Constraint and @CrossParameterConstraint, two different validators (both parameterized with <MyCustomConstraint, Object[]>) could be specified here. Not sure, how relevant this is in reality, though. An alternative would be to extend @Constraint to accommodate the specification of generic validator(s) and/or a cross-parameter validator: public @interface Constraint { Class<? extends ConstraintValidator<?, ?>>[] validatedBy() default {}; Class<? extends ConstraintValidator<?, ?>> crossParameterValidatorType() default ConstraintValidator.class; } The same rules would apply, i.e. the constraint must have a "validationAppliesTo" attribute in case validators for both cases are specified. Thinking about Matt's IMPLICIT suggestion a bit more, I guess we could even limit the cases where the constraint user must actually set the "validationAppliesTo" attribute to those cases where it can't be inferred automatically: //"validationAppliesTo" not required, since method is void @MyCustomConstraint public void foo(int p1, int p2) { ... } //not required, since method has no parameters @MyCustomConstraint public Object[] bar() { ... } //"validationAppliesTo" required if constraint has a (generic) validator for Baz and cross-param validator for Object[] @MyCustomConstraint(validationAppliesTo = ANNOTATED_ELEMENT) public Baz foo(int p1, int p2) { ... } //"validationAppliesTo" required if constraint has a (generic) validator for Object[] and cross-param validator for Object[] @MyCustomConstraint(validationAppliesTo = PARAMETERS) public Object[] foo(int p1, int p2) { ... } The ValidationTarget enum would have the values IMPLICIT (default), ANNOTATED_ELEMENT and PARAMETERS. WDYT? --Gunnar Emmanuel On Mon 2013-01-07 23:21, Gunnar Morling wrote: > Hi all, > > As per the latest spec draft, a constraint must be either a cross-parameter > *or* a generic constraint, but not both at the same time, as otherwise it > would be ambiguous whether a constraint on a method refers to the method > parameters or return value. > > Most of the time this does not really pose a limitation, but some > constraints actually might be both, cross-parameter *and* generic, > depending on the specific context. Examples are @ScriptAssert in Hibernate > Validator or generic constraints such as this: > > @EqualPasswords > public void register(String userName, String password, String > confirmedPassword) { > } > > @EqualPasswords > public class ResetPasswordRequest { > String userName; > String password; > String confirmedPassword; > } > > Based on a recent BVAL issue [1], I'm proposing to introduce a special > constraint annotation attribute, "validationAppliesTo", allowing to specify > the required behavior at the usage site: > > @EqualPasswords(validationAppliesTo=PARAMETERS) > public void register(String username, String password, String > confirmPassword) { > } > > @EqualPasswords(validationAppliesTo=ANNOTATED_ELEMENT) > public class ResetPasswordRequest { > String password; > String confirmedPassword; > } > > The following rules would apply: > > * If a constraint is annotated with @Constraint and > @CrossParameterConstraint, it must define a member "validationAppliesTo". > The default value should be ANNOTATED_ELEMENT. > * If a constraint is annotated with only one > of @Constraint/@CrossParameterConstraint, defining a "validationAppliesTo" > member doesn't have any special effect > * Specifying validationAppliesTo=PARAMETERS anywhere except a method causes > ConstraintDeclarationException > > Any thoughts? > > --Gunnar > > [1] https://hibernate.onjira.com/browse/BVAL-340 > _______________________________________________ > beanvalidation-dev mailing list > beanvalidation-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/beanvalidation-dev _______________________________________________ beanvalidation-dev mailing list beanvalidation-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/beanvalidation-dev _______________________________________________ beanvalidation-dev mailing list beanvalidation-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/beanvalidation-dev