Source: queryNodes.frm

This example application calls both the selectSingleNode method and the selectNodes method on an XML DOM object loaded from the stocks.xml file. The same XPath expression is input to both methods:

//stock[1]/*

This expression specifies all the child elements of the first <stock> element in the XML document. In MSXML, the selectSingleNode method returns the first element of the resultant node-set, and the selectNodes method returns all the elements in the node-set.

Programmatically, this source code performs the following steps:

1. Creates an instance of an XML DOM object (oXMLDom).
2. Calls the load method on oXMLDom to load XML data from a file (stocks.xml).
3. Calls the selectSingleNode method on oXMLDom to select a DOM node according to the input XPath expression (//stock[1]/*). Then displays the resulting node in the console if the query is successful.
4. Calls the selectNodes method on oXMLDom to select a DOM node-set according to the input XPath expression ("//stock[1]/*"). Then displays the resulting nodes in the console if the query is successful.

Visual Basic Source File (queryNodes.frm)

Private Sub Form_Load()
    ' Output string:
    Dim strout As String
    strout = ""
    
    ' Load an xml document into a DOM instance.
    Dim oXMLDom As New DOMDocument50
    oXMLDom.async = False
    oXMLDom.validateOnParse = False
    oXMLDom.resolveExternals = False
    oXMLDom.preserveWhiteSpace = True
    If oXMLDom.Load(App.Path + "\stocks.xml") = False Then
        MsgBox "Failed to load xml data from file."
        Exit Sub
    End If
    
    ' Query a single node.
    Dim oNode As IXMLDOMNode
    Set oNode = oXMLDom.selectSingleNode("//stock[1]/*")
    If oNode Is Nothing Then GoTo MoreNodes
        
    strout = strout _
           + "Result from selectSingleNode" + vbNewLine _
           + "Node, <" + oNode.nodeName + ">: " + vbNewLine _
           + vbTab + oNode.xml + vbNewLine + vbNewLine
    
MoreNodes:
    ' Query a node-set.
    Dim oNodes As IXMLDOMNodeList
    Set oNodes = oXMLDom.selectNodes("//stock[1]/*")
    
    strout = strout _
           + "Results from selectNodes:" + vbNewLine
    For i = 0 To oNodes.length - 1
        Set oNode = oNodes.nextNode
        If Not (oNode Is Nothing) Then
            sName = oNode.nodeName
            sData = oNode.xml
            strout = strout _
               + "Node (" + CStr(i) + "), <" + sName + ">:" _
               + vbNewLine + vbTab + sData + vbNewLine
        End If
    Next
    MsgBox strout
    
End Sub

To add queryNodes.frm to the project

• Copy the code listing above. Paste it into the Visual Basic code editor as the form_load subroutine, replacing any code fragments that are already there.

Next, we'll add the resource files to the queryNodes project.