How can I retrieve a Specific element value from an XML file?

[rdk]

Folks....Probably a simple question, but I have not been able to find the simple answer. How can I retrieve a specific value from an XML structure without travelling down the structure and iterating through all of the childnodes?

Assume the following simplified XML structure:

MyWeather>
	<sensor location="Front Entry">
		<reading label="Temperature">
			<title>Front Entry</title>
			<label>Temperature</label>
			<value>54</value>
			<units>F</units>
			<lastUpdate>05/27/2013 12:23 AM</lastUpdate>
		</reading>
		<reading label="Humidity">
			<title>Front Entry</title>
			<label>Humidity</label>
			<value>66</value>
			<units>%</units>
			<lastUpdate>05/27/2013 12:23 AM</lastUpdate>
		</reading>
	</sensor>
	<sensor location="Patio">
		<reading label="Temperature">
			<title>Patio</title>
			<label>Temperature</label>
			<value>46</value>
			<units>F</units>
			<lastUpdate>05/27/2013 12:23 AM</lastUpdate>
		</reading>
		<reading label="Humidity">
			<title>Patio</title>
			<label>Humidity</label>
			<value>93</value>
			<units>%</units>
			<lastUpdate>05/27/2013 12:23 AM</lastUpdate>
		</reading>

	</sensor>
</MyWeather>

Here is part of my ASP page:

<%
	xmlDoc = CreateObject("Msxml2.DOMDocument")
	xmldoc.setProperty ("ServerHTTPRequest", true)
	xmlDoc.setProperty ("ProhibitDTD", False)
	xmlDoc.validateOnParse = true

'    Filename is a sting variable containing the URL

	xmlDoc.async = "False"
	xmlDoc.load(FileName)

'    Error and return code processing done here but rewmoved 

	For Each el In xmldoc.childNodes
	    if el.childnodes.length <> 0 then
		response.write ("<table align='center' class='auto-style1'>")
		for each el2 in el.childnodes
		    Response.write("<tr><td>" & el2.getattribute("location") & "</td><td></td></tr>")
		    for each el3 in el2.childnodes
		        for each el4 in el3.childnodes
			    if el4.nodename = "value" then 
				Response.write("<tr><td></td><td>" & el3.getattribute("label") & " " & el4.text & " " & el4.nextSibling.text & "</td></tr>")
				exit for
			      end if
			  next
		      next
		  next
		response.write ("</table>")
	    end if
	  Next
    xmlDoc = Nothing
          
%>

My question relates to the code in the "For each el4 in ..." section. You see that I iterate through the childnodes until I find "value". Then I output that tag value and, as I know the next tag (for now until they change it), is the "units" tag I use nextsibling to get that value. This code works!

What I would like to know is:
Is there a more direct way to these two tag values for any combination of Sensor location and Reading label without my iteration process.

I have several other cases where I may need to iterate through more than 50 elements to find the tag I'm looking for.

Based on a suggestion that I should be using XPath, I added this code . This I thought would replace the "for each el4 in el3.childnodes loop" above

	xmlDoc.setProperty ("SelectionLanguage", "XPath")
	
					oNode = xmldoc.selectSingleNode("//reading[@label='Temperaure']/units")
					o2Node = xmldoc.selectSingleNode("//reading[@label='Temperaure']/value")
					if oNode is nothing or o2node is nothing then
						Response.write("<tr><td></td><td> Nothing found for value or units </td><td>" & el3.getattribute("label") & "</tr>") 
					  else
						Response.write("<tr><td></td><td>" & el3.getattribute("label") & " " & o2Node.text & " " & oNode.text & "</td></tr>")
					  end if

However, it did not work for me. I tried several variations: without the @ sign and with a full path in the oNode statements, ie /MyWeather/sensor/reading/...

My check for empty oNode and/or O2Node always is true.

Any ideas?.....RDK

[siteguru]

SelectSingleNode?

http://stackoverflow.com/questions/2225958/using-asp-vb-to-get-value-of-a-node-attribute

http://stackoverflow.com/questions/1...ng-classic-asp