Question

I have the following XML:

<?xml version="1.0" ?>
<NewDataSet>
   <Data>
     <ElementDefinition>
      <ID>1</ID>
      <QUANTITY>0</QUANTITY>
     </ElementDefinition>
     <ElementDefinition>
      <ID>2</ID>
      <QUANTITY>1</QUANTITY>
     </ElementDefinition>
   </Data>
</NewDataSet>

I need to create an array which contains all ElementDefinitions which contain a QUANTITY element with a value other then 0.

I tried:

var f = XDocument.Load(path);
var xe = f.Root.Elements("QUANTITY").Where(x => x.Value != "0").ToArray();

But that doesn’t seem to work. With the above XML the array should contain 1 item, but it stays 0.

After that I need to create a string for each ElementDefinition in the array, the string must contain the value of the corresponding ID element.

For that I tried:

foreach (string x in xe)
{
   string ID = //not sure what to do here
}

Answer 1

You want something like this:

var ids = f.Root.Descendants("ElementDefinition")
           .Where(x => x.Element("QUANTITY").Value != "0")
           .Select(x => x.Element("ID").Value);

As you want the ID, it is not very helpful to select all QUANTITY nodes. Instead, select exactly what you specified in your question:

All ElementDefinitions (Descendants("ElementDefinition")), that have a QUANTITY with a Value other than 0 (Where(x => x.Element("QUANTITY").Value != "0"). From the resulting nodes, select the ID (Select(x => x.Element("ID").Value)).