Re: Targeting all subjects & objects regardless of predicate

Hello Irene,

Thank you for helping me to understand how to use SPARQL. I now understand
better what Holger was saying in his comment in the SO answer.

I am still missing something about how to make use of this knowledge
however.

Using the SHACL Playground, let's say that I have the following Data Graph:

@prefix hr: <http://learningsparql.com/ns/humanResources#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xml: <http://www.w3.org/XML/1998/namespace> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

hr:Employee a rdfs:Class .
hr:BadThree rdfs:comment "some comment about missing" .
hr:BadTwo a hr:BadOne .
hr:YetAnother a hr:Another .
hr:YetAnotherName a hr:AnotherName .
hr:Another a hr:Employee .
hr:AnotherName a hr:name .
hr:BadOne a hr:Dangling .
hr:name a rdf:Property .

and the following Shapes Graph:

@prefix hr: <http://learningsparql.com/ns/humanResources#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xml: <http://www.w3.org/XML/1998/namespace> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix schema: <http://schema.org/> .
@prefix sh: <http://www.w3.org/ns/shacl#> .

schema:SchemaShape
    a sh:NodeShape ;
    sh:target [
        a sh:SPARQLTarget ;
        sh:prefixes hr: ;
        sh:select """
            SELECT ?this
            WHERE {
                ?this ?p ?o .
            }
            """ ;
    ] ;

    sh:property [
        sh:path rdf:type ;
        sh:nodeKind sh:IRI ;
        sh:hasValue rdfs:Class
    ] ;
.

What I think should happen is the SPARQL based target should select every
subject in the Data Graph and then verify that there is a path of rdf:type
which has a value of rdfs:Class.

However, the https://shacl.org/playground/ reports no validation errors.

The expected validation errors should include the following subjects:

| <http://learningsparql.com/ns/humanResources#BadOne>         |
| <http://learningsparql.com/ns/humanResources#BadTwo>         |
| <http://learningsparql.com/ns/humanResources#BadThree>       |
| <http://learningsparql.com/ns/humanResources#AnotherName>    |
| <http://learningsparql.com/ns/humanResources#name>           |
| <http://learningsparql.com/ns/humanResources#YetAnotherName> |

What am I missing?

Regards,
James



On Fri, Apr 10, 2020 at 10:51 PM Irene Polikoff <irene@topquadrant.com>
wrote:

> Hi James,
>
> You can use SPARQL query to target anything you want  - as shown in the
> example here https://w3c.github.io/shacl/shacl-af/#SPARQLTarget.
>
> Strictly speaking, your query would not do it. It will not catch something
> like this:
>
> ex:R1 ex:p ex:R2
>
> Where there are no triples with ex:R2 or ex:p as subjects.
>
> On Apr 10, 2020, at 9:43 PM, James Hudson <jameshudson3010@gmail.com>
> wrote:
>
> Hello Irene,
>
> You are correct, it does not. That was an error on my part, I missed that
> it does not also include all the results returned by
>
> SELECT DISTINCT ?s
> WHERE {
>     {
>         ?s ?p ?o .
>         FILTER NOT EXISTS {
>             ?s a ?c .
>             FILTER(?c IN (rdfs:Class, rdf:Property))
>         }
>     }
> }
>
>
> If I understand your comment correction regarding the SHACL Advanced
> Features, SHACL is capable of performing the validation check?
>
> I would love to see how that would be written...
>
> Regards,
> James
>
>
> On Fri, Apr 10, 2020 at 5:08 PM Irene Polikoff <irene@topquadrant.com>
> wrote:
>
>> How does your query find resources that have no type?
>>
>> As for ensuring that the type in either a class or a property, you could
>> for example do the following:
>>
>> ex:Shape1 a sh:NodeShape;
>> sh:targetSubjectsOf rdf:type;
>> sh:or (
>> [
>> sh:path rdf:type ;
>> sh:class rdfs:Class ;
>> ]
>> [
>> sh:path rdf:type ;
>> sh:class rdf:Property ;
>> ]
>> ) .
>>
>> Btw, SHACL Advanced Features supports SPARQL-based targets
>> https://w3c.github.io/shacl/shacl-af/.
>>
>> On Apr 10, 2020, at 4:21 PM, James Hudson <jameshudson3010@gmail.com>
>> wrote:
>>
>> Hello,
>>
>> I asked a question on SO (
>> https://stackoverflow.com/questions/60993789/targeting-all-nodes-for-validation
>> ) regarding how to verify that every node in my graph had a rdf:type and
>> that the type was ultimately either a rdfs:Class or rdf:Property. The
>> response I received was that it was impossible with SHACL because:
>>
>> The problem is that none of the four built-in target types is sufficient
>> to reach all subject/objects regardless of predicate.
>>
>> I was just wondering why such a target type does not exist or if there
>> were plans to include such a target type in the future...?
>>
>> I was able to do what I needed to do with SPARQL with the following query:
>>
>>                     {
>>                         ?s rdf:type+ ?o .
>>                         FILTER NOT EXISTS {
>>                             ?s rdf:type+ ?c .
>>                             FILTER(?c IN (rdfs:Class, rdf:Property))
>>                         }
>>                     }
>>
>> but, I would have preferred to use SHACL.
>>
>> Regards,
>> James
>>
>>
>>
>