Question

Hi I’m having trouble extracting data from this XML document.

  <messages messageCount="6">
  <message messageID="9999" orderNumber="1234" model="TESTMODEL" val="490" status="8" timestamp="2012-07-12 13:12:50Z">
  <attributes>
  <attribute name="ATT1" value="1234" /> 
  <attribute name="ATT2" value="5678" /> 
  </attributes>
  </message>
  </messages>

I need to recursively loop through each message and get the values of the message node. I then need to loop through the attributes and get the value of the attribute nodes if the status is a certain value. I’m having a bit of trouble. So far I have this

        Dim strStream As New MemoryStream(System.Text.Encoding.UTF8.GetBytes(strMessage))

        Dim XmlDoc As XmlDocument = New XmlDocument

        XmlDoc.Load(strStream)


        Dim nlNodeList As XmlNodeList = XmlDoc.SelectNodes("//messages/message")
        Dim a As XmlAttribute

        For Each nNode As XmlNode In nlNodeList
            Dim strmessageID As String = String.Empty
            For Each a In nNode.Attributes
                If a.Name = "messageID" Then
                    strmessageID = a.Value
                End If
            Next
            For Each nChildNode As XmlNode In nNode.ChildNodes
                For Each b In nChildNode.ChildNodes
                    For Each a In b.Attributes
                        If a.Name = "ATT1" Then

                        End If
                    Next
                Next
            Next
        Next

but i’m having trouble getting the attribute values. I’m sure there must be a cleaner way of doing this too. I was previously using Datasets and was fine until I tried to get to the attributes values

    For Each dr As DataRow In dsmyDS.Tables("message").Rows
        Dim strMessageID As String = dr.Item("messageid").ToString
        Select Case CStr(dr.Item("model").ToString)
            Case "TESTMODEL"
                Select Case dr.Item("status").ToString
                    Case "8"
                        Dim strval As String = dr.Item("val").ToString
                        'Don't know how to get at the attributes node list once I'm here
                    Case Else

                End Select
            Case Else

        End Select
    Next

It would great if someone could tell me what I’m doing wrong. Which is the best method to use? XMLDocument or a Dataset? Is there an easier way then my longwinded method?

Any help would be great thanks!

Answer 1

You should try LINQ-XML Import the System.Data.Xml.

 Dim doc As XDocument = XDocument.Load(file)
'Or
'Dim doc As XDocument = XDocument.Parse(strMessage)
 Dim Result = doc.Root.Descendants("message")
                      .Where(Function(p)
                                Return p.Attribute("status").Value = "8"
                             End Function)
 For Each ele In Result
     MsgBox(ele.Attribute("messageID").Value)
     MsgBox(ele.Element("attributes").Element("attribute").Attribute("name").Value)

     'List children of attributes tag
     For Each v In ele.Element("attributes").Elements()
          MsgBox(v.Attribute("name").Value & " " & v.Attribute("value").Value)
     Next
 Next