Re: [hibernate-dev] [Validator] Applying constraints to property objects

2013/9/4 Emmanuel Bernard <emmanuel(a)hibernate.org&gt; > On Wed 2013-09-04 8:27, Gunnar Morling wrote: > > 2013/9/3 Emmanuel Bernard <emmanuel(a)hibernate.org&gt; > > > > > Something like c makes sense. > > > > > > > Ok. > > > > > > > It similar to the notion of converter in JPA. > > > > > > But why not the following style of interfaces > > > > > > interface Convert<From,To> { > > > To convert(From); > > > } > > > > > > > Yes, thinking more about it, it probably makes sense to support multiple > > converters, e.g. in case someone works with UIInput and *Property in the > > same application. Then the "From" parameter makes sense to avoid casts > > within the converter implementation. Need to experiment with it a bit. > > More than just the cast in the impl, its a way to statically know that > you have a converter that takes From and only From, so you can restrict > the list of converters to consider to 0 or 1 all the time (assuming we > don't support multiple converters of the same From. > > > > > Regarding the name, I find "Converter" a bit too generic, in particular > > since it needs not only to convert the actual property value but also the > > static type so you can reject this (because @Size can't be applied to > > Object): > > Not sure I follow, before the core HV work, it converts a property or > class from From to To and from there you are good to go. > > Are you saying that if From = UIInput<String> we would not be able to > separate it from UIInput<Object> statically? I *think* we can, just like > we do for collections in JPA. > No, I'm not saying that. I also think we can separate that. There is two steps involved: * Resolve the correct validator for the validated element, using its declared (static) type; E.g. in the following case we'd need to find the validator for @Size/String: @Size(min=3) UIInput<String> name; While in this case we'd have to throw an exception since there is no validator for @Size/Object: @Size(min=3) UIInput<Object> name; For this step I envisioned the method "Type getDeclaredType(Type sourceType)" (better name to be found, unwrapDeclaredType()?), which would return the "real" type to consider for validator resolution (here, String or Object, respectively). * If we have found the right validator, use it to validate the given value. For this step I envisioned the getValidatedValue() method which obtains the value from the given wrapped property before passing it to the validator.