java - 如何为没有 id 的 XML 节点迭代 RML 映射语言？

Question

我想使用不带 id 属性的迭代来迭代 XML 节点，如我的代码中所示，这可能吗？我是 RML 映射语言的初学者。我正在使用 RML 映射工具，其链接在这里 https://github.com/RMLio/RML-Mapper

我已经使用“ID”成功进行了迭代，但我不想使用 id 进行迭代，因为我的 XML 数据不包含 id，所以是否可以在没有 ID 属性的情况下进行迭代，或者必须使用 id 进行迭代在 RML 映射中。请给您建议

这是我的 XML 文件数据

<MainNode>
   <Header>
      <code>404</code>
      <title>demoxml1</title>
   </Header>
   <Employees>
      <Employee **id="1"**>
         <EmpNo>1</EmpNo>
         <EmpSex>2</EmpSex>
         <BirthYear>1991</BirthYear>
         <Postcode>12345</Postcode>         
         <Indications>
            <Indication id="2">
               <IndicationNo>1</IndicationNo>
               <StartDate>11-12-2016</StartDate>               
            </Indication>
         </Indications>
      </Employee>
      <Employee id="2">
         <EmpNo>2</EmpNo>
         <EmpSex>2</EmpSex>
         <BirthYear>1992</BirthYear>
         <Postcode>12345</Postcode>
         <Indications>
            <Indication id="2">
               <IndicationNo>1</IndicationNo>
               <StartDate>11-12-2016</StartDate>               
            </Indication>
         </Indications>
      </Employee>
   </Employees>
</MainNode>

这是我的 RML 映射文件:

@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 test: <http://www.example.com/organization>.
@prefix xsd: <http://www.w3.org/2001/XMLSchema#>.
@prefix ex: <http://www.example.com/> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>.
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>.
@prefix ns1: <http://www.example.com/organization/DataProperty/Employee/> .
@prefix ns2: <http://www.example.com/organization/DataProperty/Employee/Indication/> .

<#EmployeeMapping>
rml:logicalSource [ 
    rml:source "src/test/rmlmapping/test_example.xml";
    rml:iterator "/MainNode/Employees/Employee";
    rml:referenceFormulation ql:XPath;
];
rr:subjectMap [
        rr:template "http://www.example.com/Employee#{@id}"; 
        rr:class test:Employee;
            ];


    rr:predicateObjectMap [

        rr:predicate ns1:EmpNo;
        rr:objectMap [ rml:reference "EmpNo" ];
    ];

        rr:predicateObjectMap [
        rr:predicate ns1:EmpSex;
        rr:objectMap [ rml:reference "EmpSex" ];
    ];

    rr:predicateObjectMap [
        rr:predicate ns1:BirthYear;
        rr:objectMap [ rml:reference "BirthYear" ];
    ];
    rr:predicateObjectMap [
        rr:predicate ns1:Postcode;
        rr:objectMap [ rml:reference "Postcode" ];
    ];

    rr:predicateObjectMap [
        rr:predicate ns1:Indication;
        rr:objectMap [ 
            rr:parentTriplesMap <#IndicatieMapping>;            
        ];
    ].
<#IndicatieMapping>
  rml:logicalSource [
    rml:source "src/test/rmlmapping/test_example.xml" ;
    rml:iterator "/MainNode/Employees/Employee/Indications/Indication";
    rml:referenceFormulation ql:XPath;
  ];

  rr:subjectMap [ 
    rr:template "http://www.example.com/Employee/Indication#{@id}";
    rr:class test:Indication;   
  ];

  rr:predicateObjectMap [
    rr:predicate ns2:IndicationNo;
    rr:objectMap [
      rml:reference "IndicationNo";
    ]; 
  ];

  rr:predicateObjectMap [
    rr:predicate ns2:StartDate;
    rr:objectMap [
      rml:reference "StartDate";
    ]; 
  ].

这是我的 RML 映射输出:

<http://www.example.com/Employee#1> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.example.com/organizationEmployee> .
<http://www.example.com/Employee#1> <http://www.example.com/organization/DataProperty/Employee/Indication> <http://www.example.com/Employee/Indication#2> .
<http://www.example.com/Employee/Indication#2> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.example.com/organizationIndication> .
<http://www.example.com/Employee/Indication#2> <http://www.example.com/organization/DataProperty/Employee/Indication/StartDate> "11-12-2016" .
<http://www.example.com/Employee/Indication#2> <http://www.example.com/organization/DataProperty/Employee/Indication/IndicationNo> "1" .
<http://www.example.com/Employee#1> <http://www.example.com/organization/DataProperty/Employee/BirthYear> "1991" .
<http://www.example.com/Employee#1> <http://www.example.com/organization/DataProperty/Employee/EmpNo> "1" .
<http://www.example.com/Employee#1> <http://www.example.com/organization/DataProperty/Employee/EmpSex> "2" .
<http://www.example.com/Employee#1> <http://www.example.com/organization/DataProperty/Employee/Postcode> "12345" .
<http://www.example.com/Employee#2> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.example.com/organizationEmployee> .
<http://www.example.com/Employee#2> <http://www.example.com/organization/DataProperty/Employee/Indication> <http://www.example.com/Employee/Indication#2> .
<http://www.example.com/Employee/Indication#2> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.example.com/organizationIndication> .
<http://www.example.com/Employee/Indication#2> <http://www.example.com/organization/DataProperty/Employee/Indication/StartDate> "11-12-2016" .
<http://www.example.com/Employee/Indication#2> <http://www.example.com/organization/DataProperty/Employee/Indication/IndicationNo> "1" .
<http://www.example.com/Employee#2> <http://www.example.com/organization/DataProperty/Employee/BirthYear> "1992" .
<http://www.example.com/Employee#2> <http://www.example.com/organization/DataProperty/Employee/EmpNo> "2" .
<http://www.example.com/Employee#2> <http://www.example.com/organization/DataProperty/Employee/EmpSex> "2" .
<http://www.example.com/Employee#2> <http://www.example.com/organization/DataProperty/Employee/Postcode> "12345" .

例如，我想在 RMl 映射中迭代员工节点明智和指示节点明智迭代。您可以提供您的评论吗？我必须使我的 XML 文档节点像示例员工节点、指示节点等一样具有属性 id或者没有它也是可以的。

Answer 1

在当前映射中，您没有使用 id 属性进行迭代。因为你的迭代器是

rml:iterator "/MainNode/Employees/Employee";

和

rml:iterator "/MainNode/Employees/Employee/Indications/Indication";

请注意缺少 id 属性。

您似乎只使用 id 属性来生成主题 IRI:

  rr:subjectMap [
    rr:template "http://www.example.com/Employee#{@id}"; 
    rr:class test:Employee;
  ];

和

  rr:subjectMap [ 
    rr:template "http://www.example.com/Employee/Indication#{@id}";
    rr:class test:Indication;   
  ];

你可以例如分别根据“EmpNo”和“InductionNo”创建主题。但这取决于您的源数据，这些属性是否足以用于 IRI 生成。