Question

I am a .net beginner.

I am trying to update my xml file using linq.

I got stuck at the very first point of it i.e i cant grab the value from xml file using linq.

These are the controls I am using in my code:

cbBrandName -- combobox
cbProduct   -- combobox
txtQuantity -- TextBox

I am trying the below code:

XElement doc = XElement.Load(@"..\..\stock.xml");
string quantity = doc.Descendants("quantity")
                  .Select(y => y.Element("quantity").Value.Equals(txtQuantity.Text))
/*red scribbles to 'Element' in 'where'*/ 
                  .Where(x => x.Element("productname").Value.Equals(cbProduct.Text) &&
                  x.Element("brandname").Value.Equals(cbBrandName.Text)).ToString();
MessageBox.Show(quantity.ToString());

here I am trying to store the “quantity” value in quantity string so that i can manipulate it later and then again update to my xml file.

when I make .select as comment it isn’t showing any errors but when i run it, instead of text it is showing some system.linq.Enumerable + ..... in the MessageBox.

EDIT:

when i give .toString() at the end it. It is showing error — “Object reference not set to an instance of an object.” when i run it.

Please help

Thanks in Advance.

Answer 1

XElement doc = XElement.Load(AppDomain.CurrentDomain.BaseDirectory + "/App_Data/XMLFile.xml");
        string quantity = doc.Descendants("items")
        .Select(y => y.Element("quantity").Value)
        .Where(x => x.Element("productname").Value.Equals(cbProduct.text) && x.Element("brandname").Value.Equals(cbBrandName.text))
        .Single().Element("quantity").Value;

THIS WORKS

UPDATING XML VALUE

 doc.Descendants("items")
    .Where(x => x.Element("productname").Value.Equals(cbProduct.Text) && x.Element("brandname").Value.Equals(cbBrandName.Text))
    .Single().Element("quantity").SetValue(quantity);
        doc.Save(AppDomain.CurrentDomain.BaseDirectory + "/App_Data/XMLFile.xml");