Question

我正在尝试使用dotNetRDF修改Rdf节点，然后将其保存在新文件中，但我得到相同的文件!!

我想将Identification / 12更改为Identification / 18.

模板文件：

@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>.
@prefix owl:  <http://www.w3.org/2002/07/owl#>.
@prefix xsd:  <http://www.w3.org/2001/XMLSchema#>.
@prefix qudt: <http://qudt.org/schema/qudt#>.
@prefix qudt-unit: <http://qudt.org/vocab/unit#>.
@prefix knr: <http://kurl.org/NET/knr#>.

@prefix keak: <http://kurl.org/NET/keak#>.
@prefix keak-time: <http://kurl.org/NET/keak/time#>.
@prefix keak-eval: <http://kurl.org/NET/keak/eval#>.
@prefix keak-quantity: <http://kurl.org/NET/keak/quantity#>.
@prefix keak-ev: <http://kurl.org/NET/keak/ev#>.

@base <http://data.info/keak/knr/>.

<Identification/12> a keak-ev:Identification.

<Quantity/45> a qudt:Quantity ;
  qudt:quantityType keak-quantity:ElectricConsumption .

VB.NET代码：

Dim gKnr As IGraph = New Graph()
Dim ttlParser As TurtleParser = New TurtleParser()

'Load the file template
ttlParser.Load(gKnr, PATH_TEMPLATE)
gKnr.BaseUri = New Uri(keak_BASE_URI_Knr)

Dim oNode As INode = gKnr.CreateUriNode(New Uri("http://kurl.org/NET/keak/ev#Identification"))

'retrieve the item
Dim listRes As List(Of Triple) = gKnr.GetTriplesWithObject(oNode)
'?s = http://data.info/keak/Knr/Identification/12 , 
'?p = http://www.w3.org/1999/02/22-rdf-syntax-ns#type , 
'?o = http://kurl.org/NET/keak/ev#Identification

'modify the item
Dim tIdentification As Triple
If listRes.Count = 1 Then
    tIdentification = listRes(0)
    tIdentification.Subject.GraphUri = New Uri("http://data.info/kseak/knr/Identification/18")

End If

gKnr.Assert(tIdentification)

' Serialisation and Save
Dim ttlWriter As New CompressingTurtleWriter()
ttlWriter.DefaultNamespaces = gKnr.NamespaceMap
ttlWriter.Save(gKnr, PATH_NEW_FILE)

Answer 1

这不起作用，GraphUri是INode的属性，表示节点来自哪个图并且与节点的实际URI无关

无论INode是不可变的，您都无法像尝试那样更改节点的URI。

如果您希望更改RDF图中的URI，则需要Retract()使用该URI的所有三元组，并使用新URI和Assert()创建新的三元组。

以下示例可能是同义错误的VB，但希望它能为您提供一般性的想法：

Dim listRes As List(Of Triple) = gKnr.GetTriplesWithObject(oNode).ToList()

For Each origTriple in listRes
  gKnr.Retract(origTriple)
  Dim newTriple as Triple
  newTriple = new Triple(New Uri("http://data.info/kseak/knr/Identification/18"), origTriple.Predicate, origTriple.Object)
  gKnr.Assert(newTriple)
Next

当然，如果要更改的URI不仅仅发生在主题位置，那么您需要适当地更改逻辑

Answer 2

谢谢robV，它给了我很多帮助，我从视觉中得到了一个例外，但我设法纠正了它，这是最终的代码：

    For Each origTriple In listRes
        gKnr.Retract(origTriple)
        Dim sNode As INode = gKnr.CreateUriNode(UriFactory.Create("http://data.info/keask/Knr/Identification/18"))
        Dim newTriple As Triple
        newTriple = New Triple(sNode, origTriple.Predicate, origTriple.Object)
        gKnr.Assert(newTriple)
    Next

替换节点DotnetRDF

2 个答案: