- From: Irene Polikoff <irene@topquadrant.com>
- Date: Tue, 21 Apr 2020 14:11:43 -0400
- To: James Hudson <jameshudson3010@gmail.com>
- Cc: Public Shacl W3C <public-shacl@w3.org>
- Message-Id: <671330C1-1677-444D-9C52-45869A98D369@topquadrant.com>
Well, your target picks every resource that is a subject of a triple. I thought you wanted to make sure that they all have types. Since hr:missing does not have a type, you get a violation. That seems correct to me. If you simply wanted to say that any object in a triple with rdf:type predicate must itself have a type, then you do not need SPARQL based target. You could simply use sh:targetObjectsOf rdf:type. > On Apr 21, 2020, at 1:39 PM, James Hudson <jameshudson3010@gmail.com> wrote: > > Hello Irene, > > Unfortunately, sh:path (rdf:type rdf:type); validates: > > hr:missing rdfs:comment "some comment about missing" . > > which does not have any value of rdf:type. This focus node should produce a validation error. > > I also believe that I would actually want ( rdf:type [sh:oneOrMorePath rdf:type] ) ; as the chain could be longer then just two. However, this does not resolve the problems. > > I tried: > > @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema# <http://www.w3.org/2000/01/rdf-schema#>> . > @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns# <http://www.w3.org/1999/02/22-rdf-syntax-ns#>> . > @prefix sch: <http://schema.org/ <http://schema.org/>> . > @prefix sh: <http://www.w3.org/ns/shacl# <http://www.w3.org/ns/shacl#>> . > @prefix ex: <http://example.org/ <http://example.org/>> . > > ex:ClassOrProperty > a sh:PropertyShape ; > sh:target [ > a sh:SPARQLTarget ; > sh:select """ > SELECT ?this > WHERE { > ?this ?p ?o . > } > """ ; > ] ; > > > sh:path ( rdf:type [sh:oneOrMorePath rdf:type] ) ; > sh:in ( rdfs:Class rdf:Property ) ; > sh:maxCount 1 ; # path-maxCount > sh:minCount 1 ; # PropertyShape-path-minCount > > . > > Hoping that I could say to validate where the property path terminates and that it has to contain at least one value found in sh:in, but this produced the unwanted validation error: > > Constraint Violation in MinCountConstraintComponent (http://www.w3.org/ns/shacl#MinCountConstraintComponent <http://www.w3.org/ns/shacl#MinCountConstraintComponent>): > Severity: sh:Violation > Source Shape: ex:ClassOrProperty > Focus Node: hr:Employee > Result Path: ( rdf:type rdf:type ) > > The only thing I need to be able to do is to validate where the property path terminates and that does not seem possible with SHACL. Based on that, I have to believe that my sh:path should be sh:path [sh:zeroOrMorePath rdf:type] ; to account for focus nodes which do not have a rdf:type defined. Unfortunately, SHACL requires that every node along a path be validated with the same test and cannot just validate where the property path terminates. > > Regards, > James > > > On Tue, Apr 21, 2020 at 1:18 PM Irene Polikoff <irene@topquadrant.com <mailto:irene@topquadrant.com>> wrote: > No, I meant sequence path without any zero or more or one or more. Simply rdf:type/rdf:type as opposed to rdf:type+/rdf:type which doesn’t make much sense. > > sh:path (rdf:type rdf:type); > > See https://www.w3.org/TR/shacl/#property-paths <https://www.w3.org/TR/shacl/#property-paths> > >> On Apr 21, 2020, at 12:56 PM, James Hudson <jameshudson3010@gmail.com <mailto:jameshudson3010@gmail.com>> wrote: >> >> Hello Irene, >> >> Thank you for your quickly reply. >> >> If I try: >> >> @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema# <http://www.w3.org/2000/01/rdf-schema#>> . >> @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns# <http://www.w3.org/1999/02/22-rdf-syntax-ns#>> . >> @prefix sch: <http://schema.org/ <http://schema.org/>> . >> @prefix sh: <http://www.w3.org/ns/shacl# <http://www.w3.org/ns/shacl#>> . >> @prefix ex: <http://example.org/ <http://example.org/>> . >> >> ex:ClassOrProperty >> a sh:PropertyShape ; >> sh:target [ >> a sh:SPARQLTarget ; >> sh:select """ >> SELECT ?this >> WHERE { >> ?this ?p ?o . >> } >> """ ; >> ] ; >> >> >> sh:path ( [sh:zeroOrMorePath rdf:type] rdf:type ) ; >> sh:in ( rdfs:Class rdf:Property ) ; >> . >> >> which is what I think you mean by "rdf:type/rdf:type as the path", I still get the following unexpected validation error: >> >> Constraint Violation in InConstraintComponent (http://www.w3.org/ns/shacl#InConstraintComponent <http://www.w3.org/ns/shacl#InConstraintComponent>): >> Severity: sh:Violation >> Source Shape: ex:ClassOrProperty >> Focus Node: hr:Longer >> Value Node: hr:Employee >> Result Path: ( [ sh:zeroOrMorePath rdf:type ] rdf:type ) >> >> By unexpected, I mean I do not want it to be considered a validation error because the rdf:type property path terminates at rdfs:Class. >> >> When you say "zero or more paths will deliver values hr:Long, hr:Employee, rdfs:Class," does that mean that the sh:in test will be performed on the value of hr:Long (fail), hr:Employee (fail), and rdfs:Class (pass)? Is it possible to have it validate only where the property path terminates? >> >> Regards, >> James >> >> On Tue, Apr 21, 2020 at 12:12 PM Irene Polikoff <irene@topquadrant.com <mailto:irene@topquadrant.com>> wrote: >> This looks correct. >> >> With data: >> >> hr:Long a hr:Employee. >> hr:Employee a rdfs:Class. >> >> If your focus node is hr:Long, zero or more paths will deliver values hr:Long, hr:Employee, rdfs:Class. One or more paths will deliver values hr:Employee, rdfs:Class. >> >> You could try rdf:type/rdf:type as the path. This will get the type of a resource that is used as a type and ensure that it is rdfs:CLass or rdf:Property. >> >>> On Apr 21, 2020, at 11:39 AM, James Hudson <jameshudson3010@gmail.com <mailto:jameshudson3010@gmail.com>> wrote: >>> >>> Hello, >>> >>> Since people here have been so helpful in the past, I thought I would ask a few more questions. >>> >>> Background to this is my SO question at https://stackoverflow.com/questions/61323857/what-is-the-difference-between-these-shape-graphs-which-use-shor <https://stackoverflow.com/questions/61323857/what-is-the-difference-between-these-shape-graphs-which-use-shor> >>> >>> The SO question has the data graph under consideration. >>> >>> In the book Validating RDF, it says: >>> >>> Node shapes declare constraints directly on a node. Property shapes declare constraints on the values associated with a node through a path. >>> >>> Based on this, I believe I want to use a Property Shape because I want to define a constraint on the value of the rdf:type path on a focus node. Is this correct? >>> >>> If I try the property shape: >>> >>> @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema# <http://www.w3.org/2000/01/rdf-schema#>> . >>> @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns# <http://www.w3.org/1999/02/22-rdf-syntax-ns#>> . >>> @prefix sch: <http://schema.org/ <http://schema.org/>> . >>> @prefix sh: <http://www.w3.org/ns/shacl# <http://www.w3.org/ns/shacl#>> . >>> @prefix ex: <http://example.org/ <http://example.org/>> . >>> >>> ex:ClassOrProperty >>> a sh:PropertyShape ; >>> sh:target [ >>> a sh:SPARQLTarget ; >>> sh:select """ >>> SELECT ?this >>> WHERE { >>> ?this ?p ?o . >>> } >>> """ ; >>> ] ; >>> >>> >>> sh:path [sh:zeroOrMorePath rdf:type] ; >>> sh:in ( rdfs:Class rdf:Property ) ; >>> . >>> >>> I get the unexpected validation error: >>> (J) >>> Constraint Violation in InConstraintComponent (http://www.w3.org/ns/shacl#InConstraintComponent <http://www.w3.org/ns/shacl#InConstraintComponent>): >>> Severity: sh:Violation >>> Source Shape: ex:ClassOrProperty >>> Focus Node: hr:Longer >>> Value Node: hr:Employee >>> Result Path: [ sh:zeroOrMorePath rdf:type ] >>> >>> The way I thought [sh:zeroOrMorePath rdf:type] ; would work is that it would consider the node hr:Longer and follow the rdf:type path through hr:Employee to where it terminates at rdfs:Class and then validate. However, it seems to stop one step away, sees that hr:Employee is not a rdfs:Class or rdf:Property and then generates a validation error. >>> >>> I get another unexpected validation error: >>> (K) >>> Constraint Violation in InConstraintComponent (http://www.w3.org/ns/shacl#InConstraintComponent <http://www.w3.org/ns/shacl#InConstraintComponent>): >>> Severity: sh:Violation >>> Source Shape: ex:ClassOrProperty >>> Focus Node: hr:Employee >>> Value Node: hr:Employee >>> Result Path: [ sh:zeroOrMorePath rdf:type ] >>> >>> I was thinking that the zero in sh:zeroOrMorePath would see hr:Employee a rdfs:Class ; and validate. Is it the case that the zero in sh:zeroOrMorePath causes a validation engine to compare a node against itself without following or looking for the path? >>> >>> I did try using sh:oneOrMorePath, but I received the validation error (J) again, but (K) did not show up. Is the reason why (K) did not show up because it was forced to see hr:Employee a rdfs:Class ; because of the one in sh:oneOrMorePath and could validate it? >>> >>> Perhaps a validation engine validates every node along the path and not just where the path terminates? If this is the case, is it possible to validate where the path terminates only? >>> >>> Needless to say, I am rather confused. >>> >>> Can anyone clear this up? >>> >>> Thank you, >>> James >>> >>> >>> >> >
Received on Tuesday, 21 April 2020 18:12:00 UTC