how to filter an xml file base on Id

Question

I have a small part of a xml file named "fragment.xml" which is shown below where each "SteamStuff" has their own "AttributeValue" value .So here if i click a copy button, i need to create small xml file contains only the datas of SteamStuff named "pirate".For this i have created windows form containing two buttons named "Copy" and "Paste".If i click "Copy" button it should find "fragment.xml" where it is located in my PC and need to find the managed object named "pirate" (<Text>pirate</Text>) once it finds there will be a guid <ID>b6792ed8-680b-4117-a695-9f7ef2c7752b</ID> assosiated with it ,so whereever this ID appears it should select and datas and create small xml file named "test.xml" on the same location of "fragment.xml" . So test.xml contains only datas of "pirate" What code i can implement here in button1_Click() event

<?xml version="1.0" standalone="yes"?>
<LeafDataSchema xmlns="http://tempuri.org/LeafDataSchema.xsd">
  <SteamStuff>
    <ID>b6792ed8-680b-4117-a695-9f7ef2c7752b</ID>
    <Label>pirate</Label>
    <Owner>00000000-0000-0000-0000-000000000000</Owner>
    <Image>00000000-0000-0000-0000-000000000000</Image>
    <ClassID>00000000-0000-0000-0000-000000000008</ClassID>
    <DefaultApp>00000000-0000-0000-0000-000000000000</DefaultApp>
    <Name>pirate</Name>
    <Volatile>true</Volatile>
  </SteamStuff>

  <AttributeValue>
    <ID>2977f4e0-84ab-4ad2-8c4d-6bcb49727889</ID>
    <ObjectID>b6792ed8-680b-4117-a695-9f7ef2c7752b</ObjectID>
    <Text>True</Text>
    <AttributeName>Monitor</AttributeName>
    <ClassID>00000000-0000-0000-0000-000000000008</ClassID>
  </AttributeValue>
-------------

Answer 1

Using these xml extensions: http://searisen.com/xmllib/extensions.wiki

Creating classes, because it makes it easier to see how it works:

public class XFile
{
    XElement self;

    public XFile(string file)
    {
        self = XElement.Load(file);
    }

    public XNamespace Namespace
    {
        get { return _Namespace ?? (_Namespace = self.GetDefaultNamespace()); }
    }
    XNamespace _Namespace;

    public AttributeValue[] AttributeValues
    {
        get
        {
            return _AttributeValues ??
                (_AttributeValues = self.GetEnumerable("AttributeValue", x => new AttributeValue(this, x)).ToArray());
        }
    }
    AttributeValue[] _AttributeValues;

    public SteamStuff[] SteamStuffs
    {
        get
        {
            return _SteamStuffs ??
                (_SteamStuffs = self.GetEnumerable("SteamStuff", x => new SteamStuff(this, x)).ToArray());
        }
    }
    SteamStuff[] _SteamStuffs;
}

public class SteamStuff
{
    XElement self;
    XFile parent;

    public SteamStuff(XFile parent, XElement self)
    {
        this.parent = parent;
        this.self = self;
    }

    public XElement Element { get { return self; } }

    public string ID
    {
        get { return self.Get("ID", string.Empty); }
    }

    public string Label
    {
        get { return self.Get("Label", string.Empty); }
    }
}

public class AttributeValue
{
    XElement self;
    XFile parent;

    public AttributeValue(XFile parent, XElement self)
    {
        this.parent = parent;
        this.self = self;
    }

    public XElement Element { get { return self; } }

    public string ObjectID
    {
        get { return self.Get("ObjectID", string.Empty); }
    }
}

XFile xfile = new XFile("test.xml");
SteamStuff[] pirates = xfile.SteamStuffs
                            .Where(steam => steam.Label == "pirate")
                            .ToArray();  

AttributeValue[] associated = xfile.AttributeValues
                                   .Where(av => pirates.Any(pirate => pirate.ID == av.ObjectID))
                                   .ToArray();

// write to new file
XElement fragments = new XElement(xfile.Namespace + "fragments");
foreach(SteamStuff steamStuff in pirates)
    fragments.Add(steamStuff.Element);
foreach(AttributeValue value in associated)
    fragments.Add(value.Element);

fragments.Save("fragment_file.xml");

Edit: Extensions file adjusts for the 'default' namespace.