XMLDOM / Conditional Check for Object fails

[joe]

I am having problems checking for the value of an XMLDOM object .

Lets say my XMLDOM object was successfully created as objXMLDoc, and that
has several nodes on it. In the case of a VBScript loop like below:

'-------------------
For x = 1 To 10

Set oItemPrice = objXMLDoc.selectSingleNode("//Item[x]/Price")

'--- conditional stuff that fails here

Next
'-------------------

some of the Items don't have a price, therefore the object oItemPrice will
fail at some point. So I want to check for this failure, but everything I do
gives me errors.
Examples:

1. If not oItemPrice Then
2. If oItemPrice.lenght = 0 Then
3. If oItemPrice = empty or oItemPrice = "" or isnull(oItemPrice) Then
4. If not (oItemPrice) Then

I really don't know what to do. Most errors are like:
" Object doesn't support this property or method"

Any help is appreciated.

[joe]

With JScript one can just go:

oItemPrice = xmlDoc.selectSingleNode("//Item["+x+"]/Price");

if (oItemPrice) { ...do stuff }
else {...do other stuff}

but because my XMLDOM code must go inside VBScrip pages, I have to figure
the other one out.
I tried to mix both languages up and ended up with even more problems.

Post by joe
some of the Items don't have a price, therefore the object oItemPrice will
fail at some point. So I want to check for this failure, but everything I do
gives me errors.
1. If not oItemPrice Then
2. If oItemPrice.lenght = 0 Then
3. If oItemPrice = empty or oItemPrice = "" or isnull(oItemPrice) Then
4. If not (oItemPrice) Then

[Mark Schupp]

try this:

If Not IsDomTextNode( oItemPrice) Then
...

'check if selectSingleNode returned a valid text node
Function IsDomTextNode( ByRef objNode )

Dim strTmp

On Error Resume Next
strTmp = objNode.text

If Err.Number = 0 Then
IsDomTextNode = True
Else
IsDomTextNode = False
End If

End Function

You should also be able to use the nodeType property of the node to see if
it is the type you expect. I can't remember why I used to above approach.
--
--Mark Schupp

Post by joe
I am having problems checking for the value of an XMLDOM object .
Lets say my XMLDOM object was successfully created as objXMLDoc, and that
'-------------------
For x = 1 To 10
Set oItemPrice = objXMLDoc.selectSingleNode("//Item[x]/Price")
'--- conditional stuff that fails here
Next
'-------------------
some of the Items don't have a price, therefore the object oItemPrice will
fail at some point. So I want to check for this failure, but everything I do
gives me errors.
1. If not oItemPrice Then
2. If oItemPrice.lenght = 0 Then
3. If oItemPrice = empty or oItemPrice = "" or isnull(oItemPrice) Then
4. If not (oItemPrice) Then
" Object doesn't support this property or method"
Any help is appreciated.

[joe]

Mark Schupp:

Your function worked for me. Thank you!

[joe]

Lately I've been surfing the MS knowledge pages to find XML related stuff,
and I've noticed that (of the two primary scripting languages used with ASP)
Jscript has way much more prominence that VBscript in the examples given.
Acutally, most of what I found was Jscript, C++ and Visual Basic.

Is MS pushing JScript as a preferred scripting language for their present
and future technologies? Not that I care, I like JScript. Just trying to see
where things are heading...

[McKirahan]

Post by joe
Lately I've been surfing the MS knowledge pages to find XML related stuff,
and I've noticed that (of the two primary scripting languages used with ASP)
Jscript has way much more prominence that VBscript in the examples given.
Acutally, most of what I found was Jscript, C++ and Visual Basic.
Is MS pushing JScript as a preferred scripting language for their present
and future technologies? Not that I care, I like JScript. Just trying to see
where things are heading...

JScript (JavaScript, ECMAScript) are often used client-side as they are
cross-browser compatible; whereas, VBScript requires an IE browser.

[Bob Barrows [MVP]]

Post by joe
Lately I've been surfing the MS knowledge pages to find XML related
stuff, and I've noticed that (of the two primary scripting languages
used with ASP) Jscript has way much more prominence that VBscript in
the examples given. Acutally, most of what I found was Jscript, C++
and Visual Basic.
Is MS pushing JScript as a preferred scripting language for their
present and future technologies? Not that I care, I like JScript.
Just trying to see where things are heading...

IE is the only browser that will run vbscript in client-side code ... If you
want cross-browser capabilities, you need to use javascript/jscript when
writing client-side code.

Bob Barrows

[David Patow]

Sorry about coming late to this party, but I think there's a much simpler
solution ...

Set oItemPrice = objXMLDoc.selectSingleNode("//Item[x]/Price")
If Not oItemPrice Is Nothing Then
' You can use oItemPrice in here.
End If

Yes, VB and VBScript are a little odd in this area, because they prefer to
use the default property of an object when assigning and comparing. This is
why there is the special "Set" statement and the above "Is" operator, which
act upon the object pointer itself, not its default property.

[Marvin Smit]

Hi David,

you could also consider using the "For Each" statement

Dim lItemWithPrice as MSXML2.IXMLDOMElement

For Each lItemWithPrice in
objXMLDoc.selectSingleNode("//Item/Price")
' l_ItemWithPrice = "Price" element of an item.

or

For Each lItemWithPrice in
objXMLDoc.selectSingleNode("//Item[Price]")
' lItemWithPrice = "Item" element that has a child element named
"Price".

Hope this helps,

Marvin Smit



On Thu, 9 Jun 2005 05:10:03 -0700, "David Patow"

Post by David Patow
Sorry about coming late to this party, but I think there's a much simpler
solution ...
Set oItemPrice = objXMLDoc.selectSingleNode("//Item[x]/Price")
If Not oItemPrice Is Nothing Then
' You can use oItemPrice in here.
End If
Yes, VB and VBScript are a little odd in this area, because they prefer to
use the default property of an object when assigning and comparing. This is
why there is the special "Set" statement and the above "Is" operator, which
act upon the object pointer itself, not its default property.