SelectSingleNode problem in vb .net

Question posted by: bharnett (Newbie) on July 3rd, 2008 04:07 PM

I pulled this code from a different application we use to write/read data between an xml and a form. The information I am trying to read is just a string of a directory path that the user picks on the form.

Here is the XML file

Code: ( text )

<?xml version="1.0" encoding="utf-8" ?>
<root>
<settings>
<importdir>test</importdir>
<exportdir>test</exportdir>
<archivedir>test</archivedir>
</settings>
</root>

Here is the code:

Code: ( text )

Public Class Form1
Dim xSettings As New System.Xml.XmlDocument
Dim xSettingsFileName As String = String.Empty
Dim sFilePath As String
Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
xSettingsFileName = "loaderconfig.XML"
sFilePath = My.Application.Info.DirectoryPath & "\" & xSettingsFileName
'sFilePath = "C:\My Documents\Visual Studio 2005\Projects\OTPP Loader\OTPP Loader\bin\Debug\loaderconfig.xml"
refreshconfig()
End Sub
Public Sub refreshconfig()
'Clear out the text boxes to ensure nothing is there when we load the settings
Me.txtImportPath.Text = String.Empty
Me.txtExportPath.Text = String.Empty
xSettings.Load(sFilePath)
Me.txtImportPath.Text = xSettings.SelectSingleNode("root/settings/importdir").InnerText
Me.txtExportPath.Text = xSettings.SelectSingleNode("root/settings/importdir").InnerText

It is erroring on Me.txtImportPath.Text = xSettings.SelectSingleNode("root/settings/importdir").InnerText and the error I'm getting is:
Object reference not set to an instance of an object.

I don't know why this is happening as it works great in the application I grabbed this code from.

THANKS!

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insertAlias

Moderator

1,100 Posts

July 3rd, 2008
04:11 PM
#2

Re: SelectSingleNode problem in vb .net

Welcome to Bytes!

We appreciate it if you wrap your code in [code] tags (See How to Ask a Question).

This makes it easier for our Experts to read and understand it. And if it's easier for us to read, it's easier for us to help.

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MODERATOR

DrBunchman

Moderator

763 Posts

July 3rd, 2008
04:32 PM
#3

Re: SelectSingleNode problem in vb .net

Hi bharnett,

This error means that the XPath query is not evalutating to a node correctly i.e. the XPath is probably wrong.

First thing to do is test that XPath string - have you got Stylus Studio or a similar XML editor which you can use to test these queries? That will make your life much easier and I think there are some free ones out there.

Can you try putting the two forward slashes at the beginning of all of your XPath strings and see if that makes any difference. e.g.

Code: ( text )

Me.txtImportPath.Text = xSettings.SelectSingleNode("//root/settings/importdir").InnerText
Me.txtExportPath.Text = xSettings.SelectSingleNode("//root/settings/importdir").InnerText

Does that help at all?

Dr B

bharnett

Newbie

2 Posts

July 3rd, 2008
04:48 PM
#4

Re: SelectSingleNode problem in vb .net

Nevermind, just figured it out. It was loading the wrong XML file!

insertAlias

Moderator

1,100 Posts

July 3rd, 2008
05:49 PM
#5

Re: SelectSingleNode problem in vb .net

Glad you found the answer.

DrBunchman

Moderator

763 Posts

July 4th, 2008
06:43 AM
#6

Re: SelectSingleNode problem in vb .net

Quote:

Originally Posted by bharnett

Nevermind, just figured it out. It was loading the wrong XML file!

Ah, well that would help! :-)

Dr B

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