SHACL-SPARQL or SHACL + reasoner?

Support
1

Hi folks,

I wondering which is the best approach to validate data for cases where a unique identifier value is not unique in the data. Take the example data below, where Person_3 has more than one UID. This is easy to detect this violation in SHACL, using sh:minCount and sh:maxCount for the sh:targetClass :Person.

:Person_1
    a :Person ;
    :hasUniqueID :UID_A .

:Person_2
    a :Person ;
    :hasUniqueID :UID_B .

:Person_3
    a :Person ;
    :hasUniqueID :UID_C .
    :hasUniqueID :UID_D .

:Person_4
    a :Person ;
    :hasUniqueID :UID_A

The case for Person_1 and Person_4 sharing the same UID is more difficult.

Possible Solutions:

OPTION 1. SHACL-SPARQL
I am having no success translating this SPARQL query, which correctly detects UID_A as the offender, into SHACL-SPARQL. Where am I going wrong?

SELECT $this (COUNT($this) AS ?count) 
WHERE{
    ?personIRI a :Person ;
          :hasUniqueID $this .
  }  GROUP BY $this
     HAVING (?count >1)

OPTION 2 : Use a reasoner?
Define an "owl:inverseOf" for :hasUniqueID as :UIDAssignedTo , turn on the reasoner and do a sh:maxCount 1 for the sh:path :UIDAssignedTo, detecting that:

:UID_A :UIDAssignedTo :Person_4
:UID_A :UIDAssignedTo :Person_1

Employing a reasoner for this solution seems like overkill (plus, is it even possible in Stardog?)

So, what to do, and how best to do it?

Thanks for your help.

Tim

2

Hi Tim,

I shouldn't take credit because it was @evren who pointed out the most elegant solution here: just define sh:maxCount 1 on the path :hasUniqueID/^:hasUniqueID for the target class :Person. This is basically equivalent to declaring :hasUniqueID an inverse functional object property and using that as an ICV constraint (prior to SHACL).

You can also express it in SPARQL, of course.

Cheers,
Pavel

3

I'm almost there? This shape correctly flags Person_3:

# Correctly flags :Person_3 (two UIDs)
:UIDShape a sh:NodeShape ;
 sh:targetClass :Person ;
 sh:path        :hasUniqueID  ;
 sh:maxCount    1
 .

I don't follow how to employ :hasUniqueID/^:hasUniqueID .

Stardog Studio 1.11
Stardog 6.1.0

4

Hi Tim,

You would use the equivalent SHACL paths as in:

:PersonShape a sh:NodeShape ;
    sh:targetClass :Person ;
    sh:property [
        sh:path (:hasUniqueID [sh:inversePath :hasUniqueID]) ;
        sh:maxCount 1
    ] .

For completeness, let me mention another possibility using only the inverse path:

:UniqueIDShape a sh:PropertyShape ; 
    sh:targetObjectsOf :hasUniqueID ;
    sh:property [
        sh:path [sh:inversePath :hasUniqueID] ;
        sh:maxCount 1
    ] .

Best,
Evren

5

Thanks to you both for the quick turn-around on these elegant answers. The approach will be very useful.

Cheers!

Tim

6

One final thing here is that performance of SHACL validation was substantially improved in Stardog 6.2+. In 6.1 it's still a beta. Depending on the size of your data and/or the number of constraints, you may want to consider an upgrade.

Best,
Pavel

7

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