Re: rr:constant with literal or datatype

Thank you Richard

I have come to that conculsion after reading the specs carefully indeed.

Do you think such tests could be added to the suite? There a number of cases I can think of:

1. Properly use the constant value as-is with dataype or language
2. Fail if a constant-valued has rr:datatype
3. Fail if a constant-valued has rr:language

Thanks,
Tom

November 13 2014 7:10 PM, "Richard Cyganiak" <richard@cyganiak.de> wrote: 
> Tomasz,
> 
>> On 7 Nov 2014, at 17:57, tomasz.pluskiewicz@gmail.com wrote:
>> 
>> Hi
>> 
>> I haven't found such example and I'm not sure what should happen if the R2RML mapping contained a
>> constant with language tag or datatype. For example
>> 
>> [ rr:constant "someObject"^^<http://example.org/some#datatype> ]
> 
> There’s indeed no test case for this. So you’ll have to check the text of the spec.
> 
>> Should the datatype be ignored or used as if it was specified using rr:datatype?
> 
> As per R2RML §11.2:
> 
> [[
> The generated RDF term of a term map for a given logical table row is determined as follows:
> • If the term map is a constant-valued term map, then the generated RDF term is the term map's
> constant value.
> ]]
> http://www.w3.org/TR/r2rml/#generated-rdf-term
> 
> And:
> 
> [[
> The constant value of a constant-valued term map is the RDF term that is the value of its
> rr:constant property.
> ]]
> http://www.w3.org/TR/r2rml/#dfn-constant-value
> 
> So, yes, the value of rr:constant is used exactly as is, including datatype if present.
> 
>> And more interestingly what should happen for the mapping below? Answering the first question
> will
>> suggest the answer.
>> 
>> [
>> rr:constant "someObject"^^<http://example.org/some#datatype> ;
>> rr:datatype <http://example.org/some#datatype>
>> ]
> 
> [[
> A term map that is not a datatypeable term map MUST NOT have an rr:datatype property.
> ]]
> http://www.w3.org/TR/r2rml/#dfn-specified-datatype
> 
> Following the definitions, you will find that constant-valued term maps (those with rr:constant) do
> not have a term type, and therefore can’t have a term type of rr:Literal, and therefore are not
> datatypeable.
> 
> Best,
> Richard
> 
>> It looks like such cases aren't included in the test suite [1].
>> 
>> Kind regards,
>> Tom
>> 
>> [1] http://www.w3.org/2001/sw/rdb2rdf/test-cases

Received on Sunday, 16 November 2014 14:32:17 UTC