Excel VBA - XML DomDocument return attribute values - excel

Question

I am working with the following XML response in Excel VBA.
<XXXXX docType="GetSegmentSpeed" copyright="Copyright XXXXX Inc." versionNumber="12.9" createdDate="2018-11-26T15:08:37Z" statusId="0" statusText="" responseId="06d3aad3-c3aa-40a5-9d2c-f1ac8f713729">
<SegmentSpeedResultSet coverage="255">
<SegmentSpeedResults timestamp="2018-11-26T15:08:36Z">
<Segment code="213423027" type="XDS" speed="53" average="34" reference="40" score="30" c-value="63" travelTimeMinutes="0.649" speedBucket="3"/>
<Segment code="213423023" type="XDS" speed="53" average="38" reference="41" score="30" c-value="58" travelTimeMinutes="0.603" speedBucket="3"/>
<Segment code="213423026" type="XDS" speed="52" average="34" reference="39" score="30" c-value="71" travelTimeMinutes="0.486" speedBucket="3"/>
<Segment code="213423050" type="XDS" speed="52" average="34" reference="39" score="30" c-value="71" travelTimeMinutes="0.48" speedBucket="3"/>
<Segment code="213423051" type="XDS" speed="52" average="35" reference="39" score="30" c-value="78" travelTimeMinutes="0.486" speedBucket="3"/>
</SegmentSpeedResults>
</SegmentSpeedResultSet>
</XXXXX>
I want to find the total of the travelTimeMinutes attributes of Segments.
To begin with, I thought I would try and get the value for the first segment. This is my code:
Sub SegSetTimes()
' Declare Private Variables
Dim SegString As String 'Segment set to be used for calculation
Dim hReq As New WinHttpRequest 'HttpRequest path
Dim strResp As String 'Response String
Dim xmlDoc As MSXML2.DOMDocument60 'DomDocument for parsing XML
' Import Segment Set
SegString = Join(WorksheetFunction.Transpose(Range("A2", Range("A2").End(xlDown)).Value), "|XDS,")
' Call for real-time segment information
hReq.Open "Get", "http://eu.api.XXXXX.com/Traffic/XXXXX.ashx?Action=GetSegmentSpeed" & "&token=" & AuthToken & "&Segments=" & SegString
hReq.Send
' Create string from response text
strResp = hReq.ResponseText
' Import response text into DomDocument for parsing within VBA
Set xmlDoc = New MSXML2.DOMDocument60
If Not xmlDoc.LoadXML(strResp) Then
MsgBox "Load Error"
End If
Dim n As IXMLDOMNodeList
Set n = xmlDoc.SelectNodes("//XXXXX/SegmentSpeedResultSet/SegmentSpeedResults")
Dim TT As Single
TT = n.Item(0).Attributes.getNamedItem("travelTimeMinutes")
End Sub
It fails with the following error:
Run-time error '91': Object variable or With block variable not set'
When stepping through in Locals, my IXMLDOMNodeList n looks correct. I just cannot see how to get at the values I want to.
Does anybody have any suggestions?

Answer 1

Reading in from a file I use an XPath to get the relevant nodes and then extract the value using getAttribute
Public Sub testing()
Dim xmlDoc As New MSXML2.DOMDocument60, items As Object, item As IXMLDOMElement, total As Double
Set xmlDoc = New MSXML2.DOMDocument60
xmlDoc.Load "C:\Users\User\Desktop\Test.xml"
Set items = xmlDoc.SelectNodes("//Segment[#travelTimeMinutes]")
For Each item In items
total = total + item.getAttribute("travelTimeMinutes")
Next
Debug.Print total
End Sub

Answer 2

Alternatively, consider running XSLT to retrieve the sum() across all nodes without looping:
XSLT (save as .xsl file, a special .xml file to be referenced in VBA)
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output indent="yes"/>
<xsl:strip-space elements="*"/>
<xsl:template match="/XXXXX">
<result>
<xsl:value-of select="format-number(sum(descendant::Segment/#travelTimeMinutes), '#.###')"/>
</result>
</xsl:template>
</xsl:stylesheet>
XSLT Demo
VBA
Dim xmlDoc As New MSXML2.DOMDocument60, items As Object, item As IXMLDOMElement, total As Double
' NEW REFERENCES
Dim xslDoc As New MSXML2.DOMDocument60, newDoc As New MSXML2.DOMDocument60
' RETRIEVE WEB REQUEST
...same code as above...
' LOAD XML AND XSL FILES
xmlDoc.async = False
xml.LoadXML strResp
xslDoc.async = False
xslDoc.Load "C:\Path\to\XSLT\File.xsl"
' TRANSFORM XML
xmlDoc.transformNodeToObject xslDoc, newDoc
' OUTPUT RESULT (NO LOOPING)
Debug.Print newDoc.SelectSingleNode("/result").Text
' 2.704