How do I generate blank nodes as objects?

[larswik]

Sorry for asking what is maybe a newbie question, but I will ask it anyway.
If I e.g. have a hierarchical json such as:

{
  "gadgets": [
  {
    "id": "1",
    "someProperty": "xxx",
    "someOtherProperty": "yyy",
    "someCompositeProperty": [
       {
        "compositeNodeProperty": "abc",
        "compositreNodeOtherProperty": "def"
      },
       {
        "compositeNodeProperty": "ghi",
        "compositreNodeOtherProperty": "jkl"
      }
    ]
  },
  {
    "id": "2",
    "someProperty": "xyz",
    "someOtherProperty": "lmn",
    "someCompositeProperty": {
      "compositeNodeProperty": "mno",
      "compositeNodeOtherProperty": "pqr"
    }
  }
  ]
}

I would lika a result such as:

:gadget_1 a ex:Gadget ;
  ex:someProperty "xxx"^^xsd:string;
  ex:someOtherProperty "yyy"^^xsd:string;
  ex:someCompositeProperty [
    a ex:SomeClass;
    ex:compositeNodeProperty "abc"^^xsd:string;
    ex:compositeNodeOtherProperty "def"^^xsd:string;
  ];
  ex:someCompositeProperty [
    a ex:SomeClass;
    ex:compositeNodeProperty "ghi"^^xsd:string;
    ex:compositeNodeOtherProperty "jkl"^^xsd:string;
  ];
.
:gadget_2 a ex:Gadget ;
  ex:someProperty "xyz"^^xsd:string;
  ex:someOtherProperty "lmn"^^xsd:string;
  ex:someCompositeProperty [
    a ex:SomeClass;
    ex:compositeNodeProperty "mno"^^xsd:string;
    ex:compositeNodeOtherProperty "pqr"^^xsd:string;
  ];
.

[dachafra]

Hi @larswik,
In RML is still not possible to generate BlankNode without referencing the input data. For your case, you would need two TriplesMap, one for generating the ex:Gadget class instances, and another for generating the ones of ex:SomeClass.

<#Gadget> a rr:TriplesMap;
  rml:logicalSource [
    rml:source "data.json" ;
    rml:referenceFormulation ql:JSONPath;
   rml:iterator "$.gadgets.*"
  ];
  rr:subjectMap [
    rr:template "http://example.com/{id}";
   rr:class ex:Gadget
  ];
  rr:predicateObjectMap [
    rr:predicate ex:located;
    rr:objectMap [
      rr:parentTriplesMap <#SomeClass >;
      rr:joinCondition [
        rr:child "someCompositeProperty.*.compositeNodeProperty";
        rr:parent "compositeNodeProperty";
      ];
    ];
  ].

<#SomeClass> a rr:TriplesMap;
  rml:logicalSource [
    rml:source "data.json" ;
    rml:referenceFormulation ql:JSONPath;
    rml:iterator "$.gadgets.*someCompositeProperty.*"
  ];
  rr:subjectMap [
    rr:template "{compositeNodeProperty}";
   rr:class ex: SomeClass;
   rr:termType rr:BlankNode
  ];