static void Main(string[] args)
{
var xml = "<Users><UserInfo><Name>Old Name</Name><UserCart></UserCart></UserInfo></Users>";
var document = XDocument.Parse(xml);
var userCart = document.Descendants("UserInfo")
.SingleOrDefault(x => x.Descendants("Name").Single().Value == "Old Name")
?.Element("UserCart");
var newUserCart = new UserCart
{
Products = new List <Product>
{
new Product {
Name = "First"
},
new Product {
Name = "Second"
}
}
};
userCart?.ReplaceWith(newUserCart.ToXElement());
Console.WriteLine(document.ToString());
}
