Question

I have the below xml file and I need to use an xpath to get “amount” value based on “linenumber”.

    <Doc>
      <Documents>
        <Document1>
          <linenumber>800</linenumber>
          <amount>100.00</amount>
          <name>fee1</name>
        </Document1>
        <Document2>
          <linenumber>801</linenumber>
          <amount>200.00</amount>
          <name>fee2</name>
        </Document2>
        <Document3>
          <linenumber>802</linenumber>
          <amount>300.00</amount>
          <name>fee3</name>
        </Document3>
        <Document4>
          <linenumber>803</linenumber>
          <amount>400.00</amount>
          <name>fee4</name>
        </Document4>
      </Documents>
    </Doc>

I tried the xpath specified in the below function ‘GetDocumentField’ but the function call GetDocumentField(801, “amount”) did not return any value. I can’t use LINQ since it is based on .Net framework 2.0. Can anyone suggest how to write this xpath query? Thanks!

    Private Function GetDocumentField(ByVal line As Integer, ByVal field As String) As String
         Return GetValueFromXPath(String.Format("//linenumber[.='{0}']/parent::node()/{1}", line, field)))
    End Function

    Private Function GetValueFromXPath(ByVal xpath As String) As String
        Dim node As XmlNode

        node = InputXml.SelectSingleNode(xpath)

        Return GetValueFromNode(node)
    End Function

    Private Function GetValueFromNode(ByVal node As XmlNode) As String
        If node Is Nothing Then
            Return String.Empty
        End If

        If node.InnerText Is Nothing Then
            Return String.Empty
        End If

        Return node.InnerText
    End Function

Answer 1

Use this XPath expression:

/*/*/*[linenumber = '801']/amount

But before this, correct the presented non-well-formed XML document (you probably didn’t notice that there was a parsing exception when you loaded InputXml). More specifically, all amount elements have no closing tag.