Re: Required parameters of SPARQL-based Constraint Components

Hi Jakub,

what you describe can be generalized to SHACL shapes graph validation, 
i.e. applying SHACL to itself. Constraint component declarations are in 
RDF, so we have all data available for what you need. sh:parameter 
declarations by default do not test for non-optional values, because the 
spec doesn't define this as an error. So that needs to be implemented as 
an additional, explicit check.

I have implemented this as an exercise, using SHACL-SPARQL. The basic 
query is

SELECT $this ?otherPath ?path
WHERE {
     {
         ?cc a sh:ConstraintComponent .
         ?cc sh:parameter ?param .
         ?param sh:path ?path .
         FILTER NOT EXISTS { ?param sh:optional true } .
         FILTER isIRI(?path) .
     }
     $this ?path ?anyValue .
     ?cc sh:parameter ?otherParam .
     ?otherParam sh:path ?otherPath .
     FILTER (?otherParam != ?param && isIRI(?otherPath)) .
     FILTER NOT EXISTS { $this ?otherParam ?anyOther } .
}

If you include this shape into the data graph (which is your shapes 
graph) then it will report the error, e.g. in TopBraid Composer as



(This was a rather quick attempt, I hope there are not too many errors 
in the SPARQL query).

And yes, it may be possible to use something like dash:coExistsWith 
(http://datashapes.org/constraints.html#CoExistsWithConstraintComponent) 
but then you'd need to repeat this for every constraint component, while 
the solution above applies to all shapes in your graph, and all components.

HTH
Holger


On 4/10/2017 12:09, Jakub Moskal wrote:
> I defined a SPARQL-based component with two parameters, neither of 
> which is optional. When I use this component in a shape but provide 
> only one parameter, the shape is simply ignored by the ​SHACL ​API​ 
> (https://github.com/TopQuadrant/shacl) 
> <https://github.com/TopQuadrant/shacl%29>​. It only works when I 
> provide both required parameters.
>
> Is there any mechanism to create a warning ​when a shape definition 
> lack​s​​​ a required parameter? I tried using DASH dash:coExistsWith​ 
> in a definition of the component parameters​, but it didn't change 
> anything.
>
> Thanks,
> Jakub​