当父元素为空时如何添加新的XElement子元素

Question

I have an XML document with an Element that is null:

<Home>
    <Screen01 Code="BD"/>
</Home>

I want to add new child elements to the Screen01 element:

<Home>
    <Screen01 Code="BD">
        <Child1>N</Child1>
        <Child2>2</Child2>
    </Screen01>            
</Home>

The following code gives me an error "Object reference not set to an instance of an object."

Edit-I changed the code to use the way someone suggested.

 private void CreateAddRRNodes(string xmlAfterAttribsAdded)
 {
            XElement xDoc = XElement.Parse(xmlAfterAttribsAdded);
            xDoc.Element("Screen01").Add(new XElement("Child1", "N"));
            xDoc.Element("Screen01").Add(new XElement("Child2", "1"));
  }

How can I add new elements to Screen01 when it is null?

Answer 1

LINQ to XML and its XElement data type to the rescue.

c#

void Main()
{
    XElement xml = XElement.Parse(@"<Home>
                                <Screen01 Code='BD'/>
                            </Home>");

    xml.Element("Screen01").Add(new XElement("Child1", "N"));
    xml.Element("Screen01").Add(new XElement("Child2", "2"));
}

Output XML:

<Home>
  <Screen01 Code="BD">
    <Child1>N</Child1>
    <Child2>2</Child2>
  </Screen01>
</Home>