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https://issues.apache.org/jira/browse/JENA-2320?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17523161#comment-17523161
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Florian Kleedorfer commented on JENA-2320:
------------------------------------------

Thanks for the update!

I am currently working on the PR, trying to figure out if its better to do
 #  one callback method per use case in the listener, resulting in a listener 
interface with ~ 20 methods (current state of the PR as of this writing 
(0c4d27f)  
 #  one callback method in the listener that receives 'ShaclValidationEvent' 
subclasses which are use case specific.

 

both have their merits, but I am currently leaning toward 2 because you have 
the level of detail of 1 if you want, but if you don't want, you can handle any 
event at a very high level without the boilerplate code of empty listener 
method implementations. I think I'll finish variant 2 and just push it onto the 
PR, then we can compare and decide.

> Callback or more detailed report from SHACL validation
> ------------------------------------------------------
>
>                 Key: JENA-2320
>                 URL: https://issues.apache.org/jira/browse/JENA-2320
>             Project: Apache Jena
>          Issue Type: New Feature
>          Components: SHACL
>            Reporter: Florian Kleedorfer
>            Priority: Minor
>
> Summary:
> Could we make the ValidationContext constructors protected and use instance 
> methods instead of the current static factory methods (at least for 
> {{create(ValidationContext)}} so that a subclassed ValidationContext can be 
> provided for validation that can also be propagated into the sub-evaluations?
> Explanation:
> I'm working on code that quite intimately builds on jena's SHACL validation. 
> Here's what I'm trying to do: There is a set of nodes V in the data graph G 
> that I am trying to find substitutions for by other RDF nodes. A substitution 
> is valid if no shape has a violation. Now for figuring out which 
> substitutions might be valid, it is not enough to know that shape S is 
> violated on focus node F - I need to know why exactly - i.e. which of my 
> substitutions made the validation fail. I already have a system in place that 
> notices which nodes in V (or their respective substitutes) are looked at 
> during evaluation of S. Also, If the violation is of a simple property shape, 
> I can follow the {{sh:ResultPath}} of the report from F to get to the node; 
> however, if the shape uses an aggregate like {{sh:xOne}}, or a {{sh:node}} 
> the report does not help me find the culprit, I just know it's one of the 
> nodes that were looked at.
> I have two ideas how this could be fixed for me:
> *More detailed report*
> An optional, non-standard report could be generated that always allows me to 
> figure out which of my substitutions for nodes in V (or lack thereof) caused 
> the violation. Maybe it would be enough to pass the validationreport of 
> sub-evaluations through to the main one.
> or 
> *ValidationCallback*
> A callback that I can provide for an evaluation, either as a method param to 
> {{VLib.validateShape()}}, as an optional member in the ValidationContext, or 
> in a ThreadLocal. The latter may be a problem if evaluation is done in 
> multiple threads, so maybe that's not such a great idea. 
> The callback would need to be called whenever a reportEntry is added to the 
> context - also in sub-evaluations that use a new context.
> One way with minimal impact on the codebase to achieve at least the second of 
> these solutions would be to allow me to extend the {{ValidationContext}} 
> (currently not possible because of the private constructors) and to allow me 
> to return my subclassed {{ValidationContext}} in 
> {{ValidationContext.create(ValidationContext)}} - and maybe also in the 
> other, currently static, factory methods. If that was possible, I could 
> easily intercept {{reportEntry}} methods, which (I hope) is enough.
> If that is an option, I'll provide a PR, so that I can make sure the 
> suggested changes really do solve my problem.



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