How to retreive deepest XPath value from XML using VB.NET

[Goran Djuranovic]

Hi All,
Does anyone know how to retreive deepest XPath value from XML document by using VB.NET? For example, if I had an XML file like this:

<Root>
<Customer>
<Name>MyName</Name>
</Customer>
</Root>

I would like to retreive "\Root\Customer \Name" out of it. Something like:
Dim xmlDoc As XMLDocument
Dim strXPath As String = xmlDoc.GetXPath ()

TIA

Goran Djuranovic

[Cerebrus]

Re: How to retreive deepest XPath value from XML using VB.NET

Hi Goran,

I don't know how to do this using an XPath expression. But I found this
thread where Dimitre Novatchev gives the answer. Check out the whole
thread if needed.

http://www.biglist.com/lists/xsl-list/archives/200504/msg00390.html

Alternatively, you can do it using the XmlNode class, using it's
HasChildNodes property and looping through the nodes.

HTH,

Regards,

Cerebrus.

[Martin Honnen]

Re: How to retreive deepest XPath value from XML using VB.NET



Goran Djuranovic wrote:

[color=blue]
> Does anyone know how to retreive deepest XPath value from XML document
> by using VB.NET? For example, if I had an XML file like this:
>
> <Root>
> <Customer>
> <Name>MyName</Name>
> </Customer>
> </Root>
>
> I would like to retreive "\Root\Customer \Name" out of it.[/color]

Well \Root and so on is not even legal XPath syntax, I guess you want
/Root/Customer/Name
but event then in terms of the XPath data model there is a leaf text
node deeper than that element so e.g.
/Root/Customer/Name/text()
or
/Root[1]/Customer[1]/Name[1]/text()[1]
might be more precise to describe/select the deepest node.

I don't have VB.NET code for that, here is some sample C# .NET code that
should do as long as no namespaces are involved:

using System.Xml;
using System.Xml.XPat h;

public class Test {
public static void Main (string[] args) {
XPathDocument xmlDocument = new XPathDocument(" example.xml");
XPathNavigator deepestElement = GetDeepestNode( xmlDocument, "*");
if (deepestElement != null) {
Console.WriteLi ne("Found element {0}.", deepestElement. Name);
Console.WriteLi ne("Path is " + GetXPath(deepes tElement));
}
XPathNavigator deepestNode = GetDeepestNode( xmlDocument);
if (deepestElement != null) {
Console.WriteLi ne("Found node of type {0}, value {1}.",
deepestNode.Nod eType, deepestNode.Val ue);
Console.WriteLi ne("Path is " + GetXPath(deepes tNode));
}
}

public static XPathNavigator GetDeepestNode (IXPathNavigabl e xmlInput) {
return GetDeepestNode( xmlInput, "node()");
}

public static XPathNavigator GetDeepestNode (IXPathNavigabl e
xmlInput, string nodeTest) {
XPathNavigator xPathNavigator = xmlInput.Create Navigator();
XPathExpression xPathExpression = xPathNavigator. Compile("//" +
nodeTest);
xPathExpression .AddSort("count (ancestor::node ())",
XmlSortOrder.De scending, XmlCaseOrder.No ne, "", XmlDataType.Num ber);
XPathNodeIterat or nodeIterator =
xPathNavigator. Select(xPathExp ression);
if (nodeIterator.M oveNext()) {
return nodeIterator.Cu rrent;
}
else {
return null;
}
}

public static string GetXPath (XPathNavigator navigator) {
return GetXPath(naviga tor, "");
}

public static string GetXPath (XPathNavigator navigator, string
currentPath) {
string name = "";
switch (navigator.Node Type) {
case XPathNodeType.R oot:
return "/" + currentPath;
case XPathNodeType.E lement:
name = navigator.Name;
goto case XPathNodeType.T ext;
case XPathNodeType.C omment:
name = "comment()" ;
goto case XPathNodeType.T ext;
case XPathNodeType.P rocessingInstru ction:
name = "processing-instruction()";
goto case XPathNodeType.T ext;
case XPathNodeType.T ext:
if (name == "") {
name = "text()";
}
int position =
Convert.ToInt32 ((double)naviga tor.Evaluate("c ount(preceding-sibling::" +
name + ")")) + 1;
navigator.MoveT oParent();
return GetXPath(naviga tor, name + "[" + position + "]" +
(currentPath != "" ? "/" + currentPath : ""));
default:
return "";
}
}

}

If namespaces are involved it gets difficult to simply return a string,
you need to use prefixes then in the XPath expression and somehow return
how those prefixes are bound to namespace URIs.


--

Martin Honnen --- MVP XML

http://JavaScript.FAQTs.com/

[Goran Djuranovic]

Re: How to retreive deepest XPath value from XML using VB.NET

Hi Martin,
Yes, you are right. I switched "\" & "/".
Luckily, I am not using the namespaces and the code you posted is exactly
what I needed. I am posting VB.NET version below, in case someone else needs
it. And, also, thank you very much.

*************** ******* Begin Code *************** ********
Imports System.Xml

Imports System.Xml.XPat h

_

Public Class TestXML

'Entry point which delegates to C-style main Private Function

'Public Overloads Shared Sub Main()

' Main(System.Env ironment.GetCom mandLineArgs())

'End Sub

'Public Overloads Shared Sub Main(ByVal args() As String)

' Dim xmlDocument As New XPathDocument(" example.xml")

' Dim deepestElement As XPathNavigator = GetDeepestNode( xmlDocument, "*")

' If Not (deepestElement Is Nothing) Then

' Console.WriteLi ne("Found element {0}.", deepestElement. Name)

' Console.WriteLi ne(("Path is " + GetXPath(deepes tElement)))

' End If

' Dim deepestNode As XPathNavigator = GetDeepestNode( xmlDocument)

' If Not (deepestElement Is Nothing) Then

' Console.WriteLi ne("Found node of type {0}, value {1}.",
deepestNode.Nod eType, deepestNode.Val ue)

' Console.WriteLi ne(("Path is " + GetXPath(deepes tNode)))

' End If

'End Sub 'Main

Public Sub New()

End Sub

Public Sub GetDeepestXPath ()

Dim xmlDocument As New XPathDocument(" C:\xmltest.xml" )

Dim deepestElement As XPathNavigator = GetDeepestNode( xmlDocument, "*")

If Not (deepestElement Is Nothing) Then

Console.WriteLi ne("Found element {0}.", deepestElement. Name)

Console.WriteLi ne(("Path is " + GetXPath(deepes tElement)))

End If

Dim deepestNode As XPathNavigator = GetDeepestNode( xmlDocument)

If Not (deepestElement Is Nothing) Then

Console.WriteLi ne("Found node of type {0}, value {1}.",
deepestNode.Nod eType, deepestNode.Val ue)

Console.WriteLi ne(("Path is " + GetXPath(deepes tNode)))

End If

End Sub



Public Overloads Shared Function GetDeepestNode( ByVal xmlInput As
IXPathNavigable ) As XPathNavigator

Return GetDeepestNode( xmlInput, "node()")

End Function 'GetDeepestNode



Public Overloads Shared Function GetDeepestNode( ByVal xmlInput As
IXPathNavigable , ByVal nodeTest As String) As XPathNavigator

Dim xPathNavigator As XPathNavigator = xmlInput.Create Navigator()

Dim xPathExpression As XPathExpression = xPathNavigator. Compile(("//" +
nodeTest))

xPathExpression .AddSort("count (ancestor::node ())", XmlSortOrder.De scending,
XmlCaseOrder.No ne, "", XmlDataType.Num ber)

Dim nodeIterator As XPathNodeIterat or =
xPathNavigator. Select(xPathExp ression)

If nodeIterator.Mo veNext() Then

Return nodeIterator.Cu rrent

Else

Return Nothing

End If

End Function 'GetDeepestNode



Public Overloads Shared Function GetXPath(ByVal navigator As XPathNavigator)
As String

Return GetXPath(naviga tor, "")

End Function 'GetXPath



Public Overloads Shared Function GetXPath(ByVal navigator As XPathNavigator,
ByVal currentPath As String) As String

Dim name As String = ""

Select Case navigator.NodeT ype

Case XPathNodeType.R oot

Return "/" + currentPath

Case XPathNodeType.E lement

name = navigator.Name

GoTo CaseXPathNodeTy peDotText

Case XPathNodeType.C omment

name = "comment()"

GoTo CaseXPathNodeTy peDotText

Case XPathNodeType.P rocessingInstru ction

name = "processing-instruction()"

GoTo CaseXPathNodeTy peDotText

Case XPathNodeType.T ext

CaseXPathNodeTy peDotText:

If name = "" Then

name = "text()"

End If

Dim position As Integer =
Convert.ToInt32 (CDbl(navigator .Evaluate(("cou nt(preceding-sibling::" + name
+ ")")))) + 1

navigator.MoveT oParent()

Dim someString As String

If currentPath <> "" Then

'someString = name & "[" & position & "]" & "/" & currentPath

someString = name & "/" & currentPath

Else

'someString = name & "[" & position & "]"

someString = name

End If

'Return GetXPath(naviga tor, name + "[" + position + "]" +(If currentPath <>
"" Then "/" + CurrentPath Else "")) 'ToDo: Unsupported feature: conditional
(?) operator.

Return GetXPath(naviga tor, someString)

Case Else

Return ""

End Select

End Function 'GetXPath

End Class 'Test

*************** ********** End Code *************** *************** *

Thanks

Goran Djuranovic





"Martin Honnen" <mahotrash@yaho o.de> wrote in message
news:uC9G5uUPGH A.3840@TK2MSFTN GP14.phx.gbl...[color=blue]
>
>
> Goran Djuranovic wrote:
>
>[color=green]
>> Does anyone know how to retreive deepest XPath value from XML document by
>> using VB.NET? For example, if I had an XML file like this:
>> <Root>
>> <Customer>
>> <Name>MyName</Name>
>> </Customer>
>> </Root>
>> I would like to retreive "\Root\Customer \Name" out of it.[/color]
>
> Well \Root and so on is not even legal XPath syntax, I guess you want
> /Root/Customer/Name
> but event then in terms of the XPath data model there is a leaf text node
> deeper than that element so e.g.
> /Root/Customer/Name/text()
> or
> /Root[1]/Customer[1]/Name[1]/text()[1]
> might be more precise to describe/select the deepest node.
>
> I don't have VB.NET code for that, here is some sample C# .NET code that
> should do as long as no namespaces are involved:
>
> using System.Xml;
> using System.Xml.XPat h;
>
> public class Test {
> public static void Main (string[] args) {
> XPathDocument xmlDocument = new XPathDocument(" example.xml");
> XPathNavigator deepestElement = GetDeepestNode( xmlDocument, "*");
> if (deepestElement != null) {
> Console.WriteLi ne("Found element {0}.", deepestElement. Name);
> Console.WriteLi ne("Path is " + GetXPath(deepes tElement));
> }
> XPathNavigator deepestNode = GetDeepestNode( xmlDocument);
> if (deepestElement != null) {
> Console.WriteLi ne("Found node of type {0}, value {1}.",
> deepestNode.Nod eType, deepestNode.Val ue);
> Console.WriteLi ne("Path is " + GetXPath(deepes tNode));
> }
> }
>
> public static XPathNavigator GetDeepestNode (IXPathNavigabl e xmlInput) {
> return GetDeepestNode( xmlInput, "node()");
> }
>
> public static XPathNavigator GetDeepestNode (IXPathNavigabl e xmlInput,
> string nodeTest) {
> XPathNavigator xPathNavigator = xmlInput.Create Navigator();
> XPathExpression xPathExpression = xPathNavigator. Compile("//" +
> nodeTest);
> xPathExpression .AddSort("count (ancestor::node ())",
> XmlSortOrder.De scending, XmlCaseOrder.No ne, "", XmlDataType.Num ber);
> XPathNodeIterat or nodeIterator =
> xPathNavigator. Select(xPathExp ression);
> if (nodeIterator.M oveNext()) {
> return nodeIterator.Cu rrent;
> }
> else {
> return null;
> }
> }
>
> public static string GetXPath (XPathNavigator navigator) {
> return GetXPath(naviga tor, "");
> }
>
> public static string GetXPath (XPathNavigator navigator, string
> currentPath) {
> string name = "";
> switch (navigator.Node Type) {
> case XPathNodeType.R oot:
> return "/" + currentPath;
> case XPathNodeType.E lement:
> name = navigator.Name;
> goto case XPathNodeType.T ext;
> case XPathNodeType.C omment:
> name = "comment()" ;
> goto case XPathNodeType.T ext;
> case XPathNodeType.P rocessingInstru ction:
> name = "processing-instruction()";
> goto case XPathNodeType.T ext;
> case XPathNodeType.T ext:
> if (name == "") {
> name = "text()";
> }
> int position =
> Convert.ToInt32 ((double)naviga tor.Evaluate("c ount(preceding-sibling::" +
> name + ")")) + 1;
> navigator.MoveT oParent();
> return GetXPath(naviga tor, name + "[" + position + "]" +
> (currentPath != "" ? "/" + currentPath : ""));
> default:
> return "";
> }
> }
>
> }
>
> If namespaces are involved it gets difficult to simply return a string,
> you need to use prefixes then in the XPath expression and somehow return
> how those prefixes are bound to namespace URIs.
>
>
> --
>
> Martin Honnen --- MVP XML
> http://JavaScript.FAQTs.com/[/color]