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Subject:
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XPath Problem
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Posted By:
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babloo81
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Post Date:
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11/13/2003 8:03:32 AM
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How do I trap an error that can error due to Invalid Path specified in XPath. For example I am trying to look for attribute with some name say 'Test', which is not available.
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Reply By:
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pgtips
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Reply Date:
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11/13/2003 8:39:40 AM
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are you talking about using selectSingleNode method in MSXML? You could do:
Set node = domDoc.selectSingleNode("<<your XPATH>>")
If node Is Nothing Then
' its not there
Else
' it is there
Or you could do:
If domDoc.selectNodes("<<your XPATH>>").length = 0 Then
' its not there
Else
' it is there
If you just try to get the text without checking whether the node/attribute exists you'll get error 91 so you could trap for this if you want:
hth - if not pls post some code so we can see what you're using
Phil
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Reply By:
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babloo81
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Reply Date:
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11/13/2003 9:43:11 AM
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Hi,
Thanks for the response.
The problem I have is that, whenever I use "selectSingleNode". I might get the error "Object or With Block not Set". This happens when my XML does not match the XPath.
So, this code,
Set node = domDoc.selectSingleNode("<<your XPATH>>")
may give out an error before I proceed to
If node Is Nothing Then
' its not there
Else
' it is there
Thanks,
Babloo
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Reply By:
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pgtips
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Reply Date:
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11/13/2003 11:15:36 AM
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Yes that error is error 91. But you shouldn't get that error unless you try to access some property of the node/attribute without first checking that it exists.
Example:
domDoc.selectSingleNode("<<your XPATH>>").text will generate that error if the node/attrib doesn't exist, but
domDoc.selectSingleNode("<<your XPATH>>") will not error, it will just return Nothing.
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Reply By:
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babloo81
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Reply Date:
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11/14/2003 12:28:03 AM
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Hi Phil,
Thanks a lot for the help.
So, this works.
Dim x1 As New MSXML.DOMDocument
x1.loadXML ("<P><T a='1' n='ttt'/><T a='2' n='yyy'/></P>")
MsgBox x1.selectSingleNode("//T[@a=4]") Is Nothing 'Returns False
MsgBox x1.selectSingleNode("//T[@a=2]") Is Nothing 'Returns True
Wow.
Tanks again Phil.
Babloo.
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