sh:SPARQLTarget not working?

[rorlic]

I assume that the shacl playground using the shacl-engine is configured to allow the use of sh:SPARQLTarget as documented here?

If so, it incorrectly gives no validation violations for my use case while the ITB shacl validator works as expected.
If not, it unfortunately also does not work for me in a local JavaScript project that is configured to use the SPARQL validations.

import rdf from '@zazuko/env-node';
import Validator from 'shacl-engine/Validator.js'
import { validations as sparqlValidations } from 'shacl-engine/sparql.js'

export async function createValidator(files: string[]) {
  const shapes = rdf.dataset();
  for (const file of files) {
    await shapes.import(rdf.fromFile(`./src/${file}`));
  }

  const validator = new Validator(shapes, { factory: rdf, validations: sparqlValidations });
  return validator;
}

In the shapes graph I define a base class and a derived class. The base class allows for a predicate which is optional at the base class level and required for the derived class. To validate this I created a node shape which targets all instances of the derived class by using a sparql query, passing in the necessary prefixes. The node shape has a property shape that verifies that the predicate appears exactly once:

@prefix ex:   <http://example.org/> .
@prefix sh:   <http://www.w3.org/ns/shacl#> .
@prefix xsd:  <http://www.w3.org/2001/XMLSchema#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .

ex:BaseClass a rdfs:Class ; 
  rdfs:label "A base class"@en.
  
ex:something a rdf:Property ;
  rdfs:label "Some property"@en ;
  rdfs:domain ex:BaseClass ;
  rdfs:range xsd:string .
  
ex:DerivedClass a rdfs:Class; 
  rdfs:subClassOf ex:BaseClass; 
  rdfs:label "A derived class"@en .
  
ex:Ontology a owl:Ontology ;
  sh:declare [
    sh:prefix "ex" ;
    sh:namespace "http://example.org/"^^xsd:anyURI
  ], [
    sh:prefix "rdf" ;
    sh:namespace "http://www.w3.org/1999/02/22-rdf-syntax-ns#"^^xsd:anyURI
  ], [
    sh:prefix "rdfs" ;
    sh:namespace "http://www.w3.org/2000/01/rdf-schema#"^^xsd:anyURI
  ] .

ex:DerivedShape a sh:NodeShape ;
  sh:target [
    a sh:SPARQLTarget ;
    sh:prefixes ex:Ontology ;
    sh:select """
        SELECT ?this 
        WHERE { 
          ?this rdf:type/rdfs:subClassOf ex:BaseClass .
        }
      """
  ] ;
  sh:property ex:SomethingRequiredShape .

ex:SomethingRequiredShape a sh:PropertyShape ;
  sh:path ex:something;
  sh:minCount 1;
  sh:maxCount 1;
  sh:name "Some property";
  sh:description "Some property which is optional for base instances, but required for derived instances";
  sh:message "A derived instance MUST have exactly one ex:something predicate" .

For the following data shape I expect that the report is non-conforming with a violation at focus nodes ex:InvalidDerivedInstance2 and ex:InvalidDerivedInstance3.

@prefix ex: <http://example.org/> .

ex:ValidBaseInstance1 a ex:BaseClass .
ex:ValidDerivedInstance1 a ex:DerivedClass ; ex:something "something".

ex:InvalidDerivedInstance2 a ex:DerivedClass .
ex:InvalidDerivedInstance3 a ex:DerivedClass ; ex:something "something", "not allowed" .

The ITB validator gives the expected result (2 violations), while the shacl-engine returns a conforming report.

PREFIX dash:    <http://datashapes.org/dash#>
PREFIX ex:      <http://example.org/>
PREFIX graphql: <http://datashapes.org/graphql#>
PREFIX owl:     <http://www.w3.org/2002/07/owl#>
PREFIX rdf:     <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs:    <http://www.w3.org/2000/01/rdf-schema#>
PREFIX sh:      <http://www.w3.org/ns/shacl#>
PREFIX swa:     <http://topbraid.org/swa#>
PREFIX tosh:    <http://topbraid.org/tosh#>
PREFIX xsd:     <http://www.w3.org/2001/XMLSchema#>

[ rdf:type     sh:ValidationReport;
  sh:conforms  false;
  sh:result    [ rdf:type                      sh:ValidationResult;
                 sh:focusNode                  ex:InvalidDerivedInstance2;
                 sh:resultMessage              "A derived instance MUST have exactly one ex:something predicate";
                 sh:resultPath                 ex:something;
                 sh:resultSeverity             sh:Violation;
                 sh:sourceConstraintComponent  sh:MinCountConstraintComponent;
                 sh:sourceShape                ex:SomethingRequiredShape
               ];
  sh:result    [ rdf:type                      sh:ValidationResult;
                 sh:focusNode                  ex:InvalidDerivedInstance3;
                 sh:resultMessage              "A derived instance MUST have exactly one ex:something predicate";
                 sh:resultPath                 ex:something;
                 sh:resultSeverity             sh:Violation;
                 sh:sourceConstraintComponent  sh:MaxCountConstraintComponent;
                 sh:sourceShape                ex:SomethingRequiredShape
               ]
] .

[rorlic]

I may have misinterpreted the SPARQL support part.

Does the shacl-engine have support for SPARQL targets, which is defined in SHACL Advanced Features (W3C Working Group Note 08 June 2017) or is it limited to SPARQL based constraints, which are part of the Shapes Constraint Language (SHACL) (W3C Recommendation 20 July 2017)?

[rorlic]

In order for the shacl tool to find the target nodes, you need to define the ontology (base class, property and derived class) in the DATA file and not in the SHAPES file, otherwise the sh:SPARQLTarget does not find the target nodes because the SPARQL query does not find the ?c rdfs:subClassOf ex:BaseClass triple and the query returns no results.

This is clearly stated in the SHACL specification - Data Graph:

The data graph is expected to include all the ontology axioms related to the data and especially all the rdfs:subClassOf triples in order for SHACL to correctly identify class targets and validate Core SHACL constraints.

However, even after doing that it still does not work in the playground nor locally.

For completeness, the SHAPES file becomes:

@prefix ex:   <http://example.org/> .
@prefix sh:   <http://www.w3.org/ns/shacl#> .
@prefix xsd:  <http://www.w3.org/2001/XMLSchema#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .

ex:Ontology a owl:Ontology ;
  sh:declare [
    sh:prefix "ex" ;
    sh:namespace "http://example.org/"^^xsd:anyURI
  ], [
    sh:prefix "rdf" ;
    sh:namespace "http://www.w3.org/1999/02/22-rdf-syntax-ns#"^^xsd:anyURI
  ], [
    sh:prefix "rdfs" ;
    sh:namespace "http://www.w3.org/2000/01/rdf-schema#"^^xsd:anyURI
  ] .

ex:DerivedShape a sh:NodeShape ;
  sh:target [
    a sh:SPARQLTarget ;
    sh:prefixes ex:Ontology ;
    sh:select """
        SELECT ?this 
        WHERE { 
          ?this rdf:type/rdfs:subClassOf ex:BaseClass .
        }
      """
  ] ;
  sh:property ex:SomethingRequiredShape .

ex:SomethingRequiredShape a sh:PropertyShape ;
  sh:path ex:something;
  sh:minCount 1;
  sh:maxCount 1;
  sh:name "Some property";
  sh:description "Some property which is optional for base instances, but required for derived instances";
  sh:message "A derived instance MUST have exactly one ex:something predicate" .

and the DATA file becomes:

@prefix ex:   <http://example.org/> .
@prefix sh:   <http://www.w3.org/ns/shacl#> .
@prefix xsd:  <http://www.w3.org/2001/XMLSchema#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .

ex:BaseClass a rdfs:Class ; 
  rdfs:label "A base class"@en.
  
ex:something a rdf:Property ;
  rdfs:label "Some property"@en ;
  rdfs:domain ex:BaseClass ;
  rdfs:range xsd:string .
  
ex:DerivedClass a rdfs:Class; 
  rdfs:subClassOf ex:BaseClass; 
  rdfs:label "A derived class"@en .


ex:ValidBaseInstance1 a ex:BaseClass .
ex:ValidDerivedInstance1 a ex:DerivedClass ; ex:something "something".

ex:InvalidDerivedInstance2 a ex:DerivedClass .
ex:InvalidDerivedInstance3 a ex:DerivedClass ; ex:something "something", "not allowed" .

[bergos]

I added support for SPARQL targets to the experimental branch. It looks a bit different from the SPARQL target defined in the SHACL-AF specification. It's based on Node expressions. See the in-progress SHACL 1.2 specification for more details.