Wrong term type in result from Trident

[mkroetzsch]

When I query a trident data source from VLog, strings in the RDF data are returned as abstract constants with IRIs. To reporduce:

• Create a trident database from an RDF file that contains a string literal "string"
• Use that trident database in VLog as a data source and query for the data.
• The result should be <"string"> where "string" was expecteed

[CerielJacobs]

I am trying to reproduce this with the low-level VLog Java bindings, but failing miserably. I created a trident database, with one entry: <aap> <noot> “mies” If I query this using a TermQueryIterator, I get [CONSTANT: <aap>, CONSTANT: <noot>, CONSTANT: "mies”] which is correct, I think.

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On 25 Aug 2020, at 16:16, Markus Krötzsch ***@***.***> wrote: When I query a trident data source from VLog, strings in the RDF data are returned as abstract constants with IRIs. To reporduce: • Create a trident database from an RDF file that contains a string literal "string" • Use that trident database in VLog as a data source and query for the data. • The result should be <"string"> where "string" was expecteed — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or unsubscribe.

[mkroetzsch]

After some joint debugging, it turned out that the incorrect term in VLog is an untyped string "string" (distinct from the usual version "string"^^xsd:string). Rulewerk wrongly interpreted this type-less constant to refer to an abstract constant. This has been changed in Rulewerk in a recent commit.

This fixes only the appearance in Rulewerk. The string should still be encoded with xsd:string in VLog in order to join correctly with other strings from RDF sources. As it is now, a Trident database built from an RDF file with a string will not join with that same RDF file.

[irina-dragoste]

Fixed, SPARQL results remain to be tested in open issue knowsys/rulewerk#223.