SHACL: More descriptive message when a shape is both a sh:NodeShape and a sh:PropertyShape

[barthanssens]

Discussed in #4287

^{Originally posted by volkerjaenisch November 19, 2022}
Dear RDF4J Users!

Currently we am implementing SHACL for an OpenData portal (http://datenadler.de).
We are Python programmers so we planed to go with pySHACL. But our Plan B is RDF4J which we are currently using as our backend.

Testing our Plan B we stumbled over the following exception of RDF4J reading a SHAPE file.

javax.servlet.ServletException: org.eclipse.rdf4j.repository.RepositoryException: Shape with multiple types: <http://www.w3.org/ns/shacl#PropertyShape>, <http://www.w3.org/ns/shacl#NodeShape>
	org.eclipse.rdf4j.workbench.proxy.WorkbenchServlet.handleRequest(WorkbenchServlet.java:160)
	org.eclipse.rdf4j.workbench.proxy.WorkbenchServlet.service(WorkbenchServlet.java:112)
	org.eclipse.rdf4j.workbench.proxy.WorkbenchGateway.service(WorkbenchGateway.java:117)
	org.eclipse.rdf4j.workbench.base.AbstractServlet.service(AbstractServlet.java:129)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	org.eclipse.rdf4j.workbench.proxy.CacheFilter.doFilter(CacheFilter.java:64)
	org.eclipse.rdf4j.workbench.proxy.CookieCacheControlFilter.doFilter(CookieCacheControlFilter.java:56)

Root Cause

org.eclipse.rdf4j.repository.RepositoryException: Shape with multiple types: <http://www.w3.org/ns/shacl#PropertyShape>, <http://www.w3.org/ns/shacl#NodeShape>
	org.eclipse.rdf4j.http.client.SPARQLProtocolSession.execute(SPARQLProtocolSession.java:1095)
	org.eclipse.rdf4j.http.client.SPARQLProtocolSession.executeNoContent(SPARQLProtocolSession.java:1049)
	org.eclipse.rdf4j.http.client.RDF4JProtocolSession.upload(RDF4JProtocolSession.java:1103)
	org.eclipse.rdf4j.http.client.RDF4JProtocolSession.upload(RDF4JProtocolSession.java:928)
	org.eclipse.rdf4j.http.client.RDF4JProtocolSession.upload(RDF4JProtocolSession.java:919)
	org.eclipse.rdf4j.repository.http.HTTPRepositoryConnection.add(HTTPRepositoryConnection.java:447)
	org.eclipse.rdf4j.workbench.commands.AddServlet.add(AddServlet.java:94)
	org.eclipse.rdf4j.workbench.commands.AddServlet.doPost(AddServlet.java:53)
	org.eclipse.rdf4j.workbench.base.TransformationServlet.service(TransformationServlet.java:98)
	org.eclipse.rdf4j.workbench.base.AbstractServlet.service(AbstractServlet.java:129)
	org.eclipse.rdf4j.workbench.proxy.ProxyRepositoryServlet.service(ProxyRepositoryServlet.java:100)
	org.eclipse.rdf4j.workbench.proxy.WorkbenchServlet.service(WorkbenchServlet.java:215)
	org.eclipse.rdf4j.workbench.proxy.WorkbenchServlet.handleRequest(WorkbenchServlet.java:137)
	org.eclipse.rdf4j.workbench.proxy.WorkbenchServlet.service(WorkbenchServlet.java:112)
	org.eclipse.rdf4j.workbench.proxy.WorkbenchGateway.service(WorkbenchGateway.java:117)
	org.eclipse.rdf4j.workbench.base.AbstractServlet.service(AbstractServlet.java:129)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	org.eclipse.rdf4j.workbench.proxy.CacheFilter.doFilter(CacheFilter.java:64)
	org.eclipse.rdf4j.workbench.proxy.CookieCacheControlFilter.doFilter(CookieCacheControlFilter.java:56)

Can someone please explain what is going wrong.

The shape file comes from the EU
https://github.com/SEMICeu/DCAT-AP/blob/master/releases/2.1.1/dcat-ap_2.1.1_shacl_shapes.ttl

pySHACL reads and uses this file with no complains. I also checked graphDB (to make sure my RDF4J is installed correctly) with the exact same outcome.

Any help appreciated

Cheers,
Volker

[barthanssens]

Looks like the exception is thrown when a SHACL shape has a sh:name

Eg.

:Agent_Shape
    a sh:NodeShape ;
    sh:name "Agent"@en ;
    sh:property [
        sh:minCount 1 ;
        sh:nodeKind sh:Literal ;
        sh:path foaf:name ;
        sh:severity sh:Violation
    ], [
        sh:maxCount 1 ;
        sh:path dct:type ;
        sh:severity sh:Violation
    ] ;
    sh:targetClass foaf:Agent .

Doesn't work, but simply removing the sh:name "Agent"@en fixes it.

[barthanssens]

Arguably this is not a bug, since, according to the SHACL ontology (https://github.com/w3c/data-shapes/blob/gh-pages/shacl/shacl.ttl), sh:name is only a property of a sh:PropertyShape

While the DCAT-AP shacl file uses it on sh:NodeShape ...

It would be nice to have a bit more logging on which subject/shape the SHACL sail is failing (in this particular case: all nodeshapes), and/or to simply ignore sh:name and sh:description on NodeShapes

[hmottestad]

Improved logging would be nice.

[hmottestad]

Might also be nice to have a "skip invalid shapes" option.

[hmottestad]

I’m going to handle this by improving the error message. If I can I will try to add some kind of backwards tracing to log the reason for a shape being both a node shape and a property shape.

I won’t introduce a way to skip invalid shapes at the moment.