Question

I use VB to get data through my form. I have some optional fields in my form and I have a problem with the following code:

MsgBox(myXPathNavigator.SelectSingleNode( _
  "/my:Status/my:Questions/my:Questions1", Me.NamespaceManager _
).IsNode.ToString)

When the optional field 'Questions1' is inserted into the form I get the value 'true' by the IsNode() function.

If the field it is not inserted I have an exception stating that the reference is not correct (and it is indeed true). Is there a way to verify about a node, whether it is present or not in my form?

Thanks in advance, Sun

Answer 1

Just don’t do it in one step. SelectSingleNode() returns Nothing if the XPath was not found. You must catch that condition separately.

Dim q As XPathNavigator
Dim path as String

path = "/my:Status/my:Questions/my:Questions1"
q = myXPathNavigator.SelectSingleNode(path, Me.NamespaceManager)

If Not q Is Nothing Then
  MsgBox(q.ToString)
End If