Question

The program reads the values of the “File” elements of each XML File and do something about it. I need an if statement that checks first if the root element is “CONFIGURATION” (this is the way of checking whether it’s the right XML the program is reading). My problem is you cannot add .Any() to .Element, only to .Elements. And my if statement below doesn’t work, i need to change it.

Please see the comment before the if statement.

My code:

    static void queryData(string xmlFile)
    {
        var xdoc = XDocument.Load(xmlFile);
        var configuration = xdoc.Element("CONFIGURATION");

        //The code works except for the if statement that I added.
        //The debug shows that configuration is null if no "CONFIGURATION" element is found,
        //therefore it prompts a "NullReferenceException" error.
        if (configuration == xdoc.Element("CONFIGURATION"))
        {
            string sizeMB = configuration.Element("SizeMB").Value;
            string backupLocation = configuration.Element("BackupLocation").Value;
            string[] files = null;

            Console.WriteLine("XML: " + xmlFile);

            if (configuration.Elements("Files").Any())
            {
                files = configuration.Element("Files").Elements("File").Select(c => c.Value).ToArray();
            }
            else if (configuration.Elements("Folder").Any())
            {
                files = configuration.Elements("Folder").Select(c => c.Value).ToArray();
            }
            StreamWriter sw = new StreamWriter(serviceStat, true);
            sw.WriteLine("Working! XML File: " + xmlFile);
            foreach (string file in files)
            {
                sw.WriteLine(file);
            }
            sw.Close();
        }
        else 
        {
            StreamWriter sw = new StreamWriter(serviceStat, true);
            sw.WriteLine("XML Configuration invalid: " + xmlFile);
            sw.Close();
        }

Answer 1

Wouldn’t a simple null check work here?

    var configuration = xdoc.Element("CONFIGURATION");

    if (configuration != null)
    {
            // code...
    }