Question

I’m trying to retrieve values from an XML file and I find some values are empty.
textBox6, textBox7, textBox14 corresponding element attribute values are empty/null. The error message is Null reference error was unhanded . How can fix this??

private void DisplayFile(string path)
    {

        var doc = XDocument.Load(path);
        var ns = doc.Root.GetDefaultNamespace();
        var conn = doc.Root.Element(ns + "connection");

        textBox1.Text = conn.Element(ns + "sourceId").Value;


        var doc1 = XDocument.Load(path);
        var ns1 = doc.Root.GetDefaultNamespace();         
        var conn1 = doc.Root.Element(ns1 + "connectionContext");


    }

Answer 1

If a given element is not present in the XML foo.Element("someNode") will return null. When accessing .Value you get a NullReferenceException.

In order to avoid this NullReferenceException you need to check if the element is not null.

Example with contextType:

var contextType = conn1.Element(ns + "contextType");
if (contextType != null)
{
  textBox15.Text = contextType.Value;
}

Update:

You try to load the connectionContext node from the root element. But this node is a child of the source node. You need to first load this node:

var source = doc.Root.Element(ns + "source");
var conn1 = source.Element(ns + "connectionContext");