Re: Targeting classes?

Thanks Holger. That’s exactly what I am looking for. Your help is much appreciated.

With best regards,
Samson


> On Jun 20, 2019, at 5:44 PM, Holger Knublauch <holger@topquadrant.com> wrote:
> 
> Hi Samson,
> 
> I assume you want to apply some shapes to the class resources themselves, not the instances of those classes. Correct me if I am wrong, with an example maybe?
> 
> SHACL Core only defines the simple cases such as sh:targetClass, and you could theoretically enumerate the individual classes via sh:targetNode, yet this is not elegant and wouldn't dynamically discover other subclasses.
> 
> Therefore, for more complex targets you'd need to resort to custom targets. These are part of a separate document "SHACL Advanced Features" and add the ability to use any SPARQL query to select the target nodes:
> 
> https://www.w3.org/TR/shacl-af/#targets
> 
> This mechanism (which is for example implemented by the open source SHACL API and TopBraid tools). I didn't test this, but the following illustrates the idea:
> 
> ex:SubClassesShape
>     a sh:NodeShape ;
>     sh:target [
>         a sh:SPARQLTarget ;
>         sh:prefixes ex: ;
>         sh:select """
>             SELECT ?this
>             WHERE {
>                 ?this rdfs:subClassOf+ ex:ParentClass .
>             }
>             """ ;
>     ] ;
> 
> The above example would apply ex:SubClassesShape to all (transitive) subclasses of ex:ParentClass, e.g. it would validate ex:MySubClassOfParentClass itself (not its instances).
> 
> This pattern can be generalized into a SPARQL-based Target Type, so that the syntax could become:
> 
> ex:SubClassesShape
>     a sh:NodeShape ;
>     sh:target [
>         a ex:SubClassesOfClassTarget ;
>         ex:class ex:ParentClass ;
>     ] ;
> 
> You'd just need to declare this target type once and then can reuse it for any use case. If you need help declaring this correctly, let me know.
> 
> As a bit of background, earlier versions of SHACL had this feature in the main document, under SHACL-SPARQL, but we essentially ran out of time and had to move some advanced features into the separate document.
> 
> HTH and regards to Stanford,
> Holger
> 
> 
> On 21/06/2019 10:23, Samson Tu wrote:
>> Hi,
>> 
>> This is a newbie question, though I couldn’t find an answer in the SHACL spec or the mailing list archive.
>> 
>> I would like to specify shapes that subclasses of a specific class should satisfy. SHACL’s target declaration mechanisms don’t seem to allow that that kind of specification.
>> 
>> I know that I can use OWL’s punning feature to treat the classes as if they were individuals (by making the class IRIs instances of another class), but I am hoping that I don’t need to do that.
>> 
>> Any suggestions or pointers?
>> 
>> Thank you.
>> 
>> With best regards,
>> Samson
>