How to read XML

[Mondeo]

I have the following simple XML File called getvehicles.xml

 

<?xml version="1.0" encoding="utf-8" ?>

<GetVehicles release="8.1" environment="Production" lang="en-US">

<ApplicationArea>

</ApplicationArea>

<DataArea>

<Error>

</Error>

<Vehicles>

<Vehicle>

<Combined_Make>VOLVO</Combined_Make>

<Combined_Model>70 SERIES C70 T5 GT</Combined_Model>

</Vehicle>

</Vehicles>

</DataArea>

</GetVehicles>

 

I need to read the combined _make and combined_model tags. I have this code

 

Dim

 

file As String = Server.MapPath("getvehicles.xml")

Dim doc As New XmlDocument

doc.Load(file)

Dim NodeList As XmlNodeList

Dim GetVehiclesNode As XmlNode

NodeList = doc.GetElementsByTagName("GetVehicle")

For Each GetVehiclesNode In NodeList

Response.Write(GetVehiclesNode.Attributes("Combined_Make").InnerText)

Response.Write(GetVehiclesNode.Attributes("Combined_Model").InnerText)

Next

But this returns an object not set to instance of an object error. What is the correct code.

 

Many thanks, this is my first try with XML

[Agent707]

It is probably in this line

NodeList = doc.GetElementsByTagName("GetVehicle")

It's GetVehicles not GetVehicle

 

For starters, you need to understand the structure of an XML Document.

Nodes (Or tags as some prople call then) have a hierachy depending on where they are at.

Your document would look this if you indented it correctly.

<?xml version="1.0" encoding="utf-8" ?>
<GetVehicles release="8.1" environment="Production" lang="en-US">
<ApplicationArea>
</ApplicationArea>
<DataArea>
	<Error></Error>
	<Vehicles>
		<Vehicle>
			<Combined_Make>VOLVO</Combined_Make>
			<Combined_Model>70 SERIES C70 T5 GT</Combined_Model>
		</Vehicle>
	</Vehicles>
</DataArea>
</GetVehicles>

Another major thing. Combined_Model and Combined_Make are not attributes, they are Nodes.

Release, Environment and Lang are attributes (of GetVehicles)

 

You have to parse your nodes in the hierarchy they occurr in your document.

 

See if this makes sense

       Dim objNode As XmlNode
       Dim GetVehiclesNode As XmlNode
       Dim VehicleNode As XmlNode

       'Get the root node of your document (where the release number matches if you want to).
       GetVehiclesNode = doc.SelectSingleNode("GetVehicles[@release='8.1']")

       'Now get the Vehicle node that is nested down in your document like so.
       VehicleNode = GetVehiclesNode.SelectSingleNode("DataArea/Vehicles/Vehicle")

       Dim strNodeElement As String
       Dim strNodeText As String

       For Each objNode In VehicleNode
           strNodeElement = objNode.Name
           strNodeText = objNode.InnerText
       Next

Now, if you want your XML Document to have a more sensable structure, should probably do something more like this

<?xml version="1.0" encoding="utf-8" ?>
<GetVehicles release="8.1" environment="Production" lang="en-US">
<ApplicationArea>
</ApplicationArea>
<DataArea>
	<Error></Error>
	<Vehicles>
		<Vehicle>
			<make>VOLVO</make>
			<model>70 SERIES C70 T5 GT</model>
		</Vehicle>
		<Vehicle>
			<make>BMW</make>
			<model>325i</model>
		</Vehicle>
		<Vehicle>
			<make>Volks Wagon</make>
			<model>Passat</model>			
		</Vehicle>
	</Vehicles>
</DataArea>
</GetVehicles>

Then the code would be more like

       'Now get the Vehicles node that is nested down in your document like so.
       VehiclesNode = GetVehiclesNode.SelectSingleNode("DataArea/Vehicles")

       Dim strMake As String
       Dim strModel As String

       For Each objNode In VehiclesNode.SelectNodes("Vehicle")
           strMake = objNode.SelectSingleNode("make").InnerText
           strModel = objNode.SelectSingleNode("model").InnerText
       Next

Hope that makes sense. Play with it and see how you do.

 

I'm outter here for the weekend. Good luck!

Edited November 10, 2006 by Agent707

[Mondeo]

I'd just like to say thanks.

 

Your post is exactly what i've been looking for all night, I think I can get it working from here.

 

Thanks again.

[Agent707]

LOL! I just realized the structure of the 2nd document I posted is exactly the same as the one you had to begin with. Late in the day, what can I say but... Oh well.. Good that you're going on it now.

 

Cheers :)

[Mondeo]

No problem,

 

I can't change the structure of the XML file anyway becuase it comes from a 3rd party web service. And each XML stream only includes one <vehicle>, but with hundreds of fields.

 

Thanks again, its working!

 

Ben