How to add blank node in RML mapping

[vimaldarjiv26]

While testing with RML mapper I have added rr:BlankNode in RML mapping file but RML mapper doesn't allow me.

[pheyvaer]

How does your mapping file look like? And what error does the mapper return?

[ssskralin]

@andimou, in the example below, why 4 blank nodes generated instead of 2?

Input

{
   "results": [
      {
         "record_id": "ec5ca92d-865a-431f-9984",
         "demographics": { "gender":"male", "age":18 }
      },
      {
         "record_id": "0a79ecf0-83d8-4148-9054",
         "demographics": { "gender":"female", "age":19 }
      }
   ]
}

Mappings

@prefix rr: <http://www.w3.org/ns/r2rml#>.
@prefix rml: <http://semweb.mmlab.be/ns/rml#>.
@prefix ql: <http://semweb.mmlab.be/ns/ql#>.
@prefix xsd: <http://www.w3.org/2001/XMLSchema#>.
@prefix exo: <http://example.org/ontology/>.
@prefix exr: <http://example.org/resource/>.

<#RecordMapping>
  rml:logicalSource [
    rml:source "/home/kralin/Desktop/results.json";
    rml:referenceFormulation ql:JSONPath;
    rml:iterator "$.results.[*]"
  ];

  rr:subjectMap [ rr:termType rr:BlankNode ];

  rr:predicateObjectMap [
    rr:predicate exo:has_age;
    rr:objectMap [
      rml:reference "demographics.age" ;
      rr:datatype xsd:integer
    ]
  ].

<#ResultsMapping>
  rml:logicalSource [
    rml:source "/home/kralin/Desktop/results.json";
    rml:referenceFormulation ql:JSONPath;
    rml:iterator "$"
  ];

  rr:subjectMap [ rr:constant "http://example.org/resource/results" ];

  rr:predicateObjectMap [
    rr:predicate exo:has_record;
    rr:objectMap [
      rr:parentTriplesMap <#RecordMapping>
    ]
  ].

Output

exr:results exo:has_record _:NasCMHQ4qO , _:6zFBpcR1el .

_:59SyVseNjX exo:has_age 18 .

_:mEdfZ9cRrU exo:has_age 19 .

_:NasCMHQ4qO exo:has_age 18 .

_:6zFBpcR1el exo:has_age 19 .

[pheyvaer]

Hi,

We've updated the RMLMapper and it can now be found here. I've tried your example only two blank nodes are generated. If you have still issues, you can open a new issue at the repo of the new RMLMapper.