JSONPath ref to array requires iteration

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
45/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Quiet
Tech stack
java
Domain
backend

Research direction

Start with the minimal JSONPath mapping in the issue and trace how a normal reference is handled when its value is an array. Check the RML specification and compare the behavior with RMLMapper and RMLViewer; done when the expected array-reference behavior is agreed and covered by a regression test.

Written by the indexing model from the issue text.

Description

Using a normal JSONPath references (not an iterator) towards a node that is a JSON array results in an error: "Reference field reading an array without iteration." I am not sure if this is an issue or a feature, but in any case I cannot find this behavior as a requirement in the RML spec. Moreover, RMLMapper and RMLViewer do not fail on this, afaik.

Minimal example:

:mapping a rml:TriplesMap ;
  rml:logicalSource [
    # JSONPath root iterator over { "key": [ "1", "2" ] }
  ] ;
  rml:subjectMap [ rml:termType rml:BlankNode ] ;
  rml:predicateObjectMap [
    rml:predicate <urn:example:hasValue> ;
    rml:objectMap [ rml:reference "key" ] ;
  ] .
Dominant language
Java
Stars
3
Forks
1
No merged PRs in 30d

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