SelectSingleNode and NameSpaces???

[clumsybiker]

I have the following xml:

<NLIS_MESSAGE xmlns="

http://www.someurl.co.uk/NS/2001-01-10"

xmlns:xsi="

http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="

http://www.someurl.co.uk/NS/2001-01-10

Acknowledgement.xsd">
<MESSAGE_ACKNOWLEDGEMENT>
<RESPONSE_MNEMONIC>ACKNOWLEDGE</RESPONSE_MNEMONIC>
<ERROR_MNEMONIC>SUCCESS</ERROR_MNEMONIC>
</MESSAGE_ACKNOWLEDGEMENT>
</NLIS_MESSAGE>

This xml is loaded into an xmlDocument object in VB .NET.
As you can see it has several namespaces. I am struggling to understand how I can do a document.SelectSingleNode to get hold of the values of the Mnemomic fields in the message, to determine whether "Acknowledge" and "Success" are present.

When I do:
dim oNode as xmlnode = Document.SelectSingleNode("/NLIS_MESSAGE/MESSAGE_ACKNOWLEDGEMENT/RESPONSE_MNEMONIC")
I get oNode = Nothing

I've tried with a namespacemanager but still get nothing, but I think I don't know enough about namespaces / namespacemanagers to get it right.

Can anyone help?

Thanks,

 

[fatmosh]

I believe you need to add a default namespace prefix and reference it when you do any XPath queries (like SelectSingleNode).

I had a similar problem and it was fixed by doing this. Try this:

Change xmlns="

http://www.someurl.co.uk/NS/2001-01-10"

to xmlns:n="

http://www.someurl.co.uk/NS/2001-01-10"

And dim oNode as xmlnode = Document.SelectSingleNode("/NLIS_MESSAGE/MESSAGE_ACKNOWLEDGEMENT/RESPONSE_MNEMONIC")
to dim oNode as xmlnode = Document.SelectSingleNode("/n:NLIS_MESSAGE/n:MESSAGE_ACKNOWLEDGEMENT/n:RESPONSE_MNEMONIC")

And see if that works.

Also, I think you might not need the opening / before NLIS_MESSAGE, but I'm not sure about that.

Good luck!

 

[clumsybiker]

Thanks FatMosh, but I don't have control over the source xml - it comes in from a data provider hence I can't simply make changes to the namespace declarations.

For those also stuggling with this problem, I have found a solution using the namespacemanager class - although not quite in the same way as the Microsoft Developer Network examples....

I've aliased the default namespace to "def" using a NameSpaceManager - and the result is I can do SelectSingleNode in the way fatmosh specified above:

so:

'Declare the NameSpaceManager
dim oNSMgr as new XmlNameSpaceManager(Document.NameTable)
'Alias the default namespace to "def"
oNSMGR.AddNameSpace("def", "

http://www.someurl.co.uk/NS/2001-01-10")

'The node can now be selected via the NSManager, using the "def" alias
dim oNode as xmlnode = Document.SelectSingleNode("/def:NLIS_MESSAGE/def:MESSAGE_ACKNOWLEDGEMENT/def:ERROR_MNEMONIC", oNSMgr)
MsgBox(oNode.InnerText)