C# load xml data with attributes to datagridview; update data and save back to the xml

Question

Hi guys,
i currently have this XML as data
<DEALS>
<DEAL ID="22" ISBN="0-7888-1623-3" Screenplay="Mary Kaplan" Title ="Mr Gentleman" Director = "Jonathan Jones">
<ALLOCATION DEMANDE="5000" CODE="72" PRICE="25.00">2500</ALLOCATION>
<ALLOCATION DEMANDE="7000" CODE="75" PRICE="35.00">4000</ALLOCATION>
</DEAL>
<DEAL ID="23" ISBN="1-7988-1623-3" Screenplay="Joe Doe" Title ="Nothing Much" Director = "Listentome">
<ALLOCATION DEMANDE="3300" CODE="72" PRICE="15.00">2500</ALLOCATION>
</DEAL>
</DEALS>
I load the data with the code below:
i use xDocument to load the DealData.xml and then put it in ToString.
//outside of the form
public static class XElementExtensions
public static DataTable ToDataTable(this XElement element)
DataSet ds = new DataSet();
string rawXml = element.ToString();
ds.ReadXml(new StringReader(rawXml));
return ds.Tables[0];
public static DataTable ToDataTable(this IEnumerable<XElement> elements)
return ToDataTable(new XElement("Root", elements));
//in the form
private void button2_Click(object sender, EventArgs e)
var xDocument = XDocument.Load("DealData.xml");
string txtxml = xDocument.ToString();
StringReader reader = new StringReader(txtxml);
XDocument doc1 = XDocument.Load(reader);
var res = doc1.Descendants("DEAL").ToList().Where(x => x.Attribute("ID").Value == "22").Descendants("ALLOCATION");
dataGridView1.DataSource = res.ToDataTable();
Now my question is:
I would like to update the data from the DataGridview with the Attribute("ID").Value == "22" and save the data back to the XML.
For example, after I load my data on the datagridview, we only pickup anything that is in the node
<DEAL ID="22" ISBN="0-7888-1623-3" Screenplay="Mary Kaplan" Title ="Mr Gentleman" Director = "Jonathan Jones">
<ALLOCATION DEMANDE="5000" CODE="72" PRICE="25.00">2500</ALLOCATION>
<ALLOCATION DEMANDE="7000" CODE="75" PRICE="35.00">4000</ALLOCATION>
</DEAL>
I updated the datagridview below with DEMANDE = 9000 CODE = 66 PRICE = 24.77 AND ALLOCATION = 1200
I want be able to extract the data back in the xml as a child of the DEAL ID = "22"
So that the XML file looks like this 
<DEALS>
<DEAL ID="22" ISBN="0-7888-1623-3" Screenplay="Mary Kaplan" Title ="Mr Gentleman" Director = "Jonathan Jones">
<ALLOCATION DEMANDE="5000" CODE="72" PRICE="25.00">2500</ALLOCATION>
<ALLOCATION DEMANDE="7000" CODE="75" PRICE="35.00">4000</ALLOCATION>
<ALLOCATION DEMANDE="9000" CODE="66" PRICE="24.77">1200</ALLOCATION> <-! this is the new line !->
</DEAL>
<DEAL ID="23" ISBN="1-7988-1623-3" Screenplay="Joe Doe" Title ="Nothing Much" Director = "Listentome">
<ALLOCATION DEMANDE="3300" CODE="72" PRICE="15.00">2500</ALLOCATION>
</DEAL>
</DEALS>
Is there a way to achieve that?
I have been searching and reading in the books but i cannot find a solution for this.
Thank you
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Answer 1

I would think of something like the below, the id is passed as static you need to change this
protected virtual void button1_Click(object sender, EventArgs e)
//Get DataTable from DGV datasource
DataTable dt = new DataTable();
dt = (DataTable)dataGridView1.DataSource;
string file1 = "<?xml version=\"1.0\" encoding=\"utf-8\" ?><DEALS><DEAL ID=\"22\" ISBN=\"0-7888-1623-3\" Screenplay=\"Mary Kaplan\" Title =\"Mr Gentleman\" Director = \"Jonathan Jones\"><ALLOCATION DEMANDE=\"5000\" CODE=\"72\" PRICE=\"25.00\">2500</ALLOCATION><ALLOCATION DEMANDE=\"7000\" CODE=\"75\" PRICE=\"35.00\">4000</ALLOCATION></DEAL><DEAL ID=\"23\" ISBN=\"1-7988-1623-3\" Screenplay=\"Joe Doe\" Title =\"Nothing Much\" Director = \"Listentome\"><ALLOCATION DEMANDE=\"3300\" CODE=\"72\" PRICE=\"15.00\">2500</ALLOCATION></DEAL></DEALS>";
StringReader reader = new StringReader(file1);
XDocument doc1 = XDocument.Load(reader);
//Remove all elements related to the id being populated into the Grid
doc1.Descendants("DEAL").ToList().Where(x => x.Attribute("ID").Value == "22").Descendants("ALLOCATION").Remove();
//loop through datatable and create new xelement to be added to the xdocument
foreach (DataRow dr in dt.Rows)
XElement xe = new XElement("ALLOCATION",
new XAttribute("DEMANDE", dr[0].ToString()),
new XAttribute("CODE", dr[1].ToString()),
new XAttribute("PRICE", dr[2].ToString()));
xe.Value = dr[3].ToString();
doc1.Descendants("DEAL").ToList().Where(x => x.Attribute("ID").Value == "22").FirstOrDefault().Add(xe);
Fouad Roumieh