Exception in reading XML file

I am posting an example of how to read an xml from disk and deserializes it to a class. This way you do not have to be picking up each item manually. This works on an old project that I have here. Let's go for the explanations of usage.

This is the template for my xml example.

<Pages> 
  <Page>
    <Name>Page 1</Name>
    <Url>http://www.google.com</Url>
    <XPathExpression></XPathExpression>
  </Page>
  <Page>    
    <Name>Page 2</Name>
    <Url></Url>
    <XPathExpression></XPathExpression>
  </Page>  
</Pages>

This is a class I use to load xml, serialize it and deserialize it.

public class UtilXML
    {
        //Private fields        

        //Public fields 
        public XmlDocument XmlDocument { get; set; }

        public UtilXML() { }

        public void LoadXMLByPath(string FilePath)
        {
            try
            {
                XmlDocument = new XmlDocument();
                XmlDocument.Load(FilePath);               
            }
            catch (System.Xml.XmlException e)
            {
                throw new System.Xml.XmlException(e.Message);

            }
        }

        public void SerializeToXml<T>(T obj, string FileName)
        {
            XmlSerializer XmlSerializer = new XmlSerializer(typeof(T));
            FileStream FileStream = new FileStream(FileName, FileMode.Create);
            XmlSerializer.Serialize(FileStream, obj);
            FileStream.Close();
        }

        public T DeserializeFromXml<T>(string StringXML)
        {
            T Result;
            XmlSerializer XmlSerializer = new XmlSerializer(typeof(T));
            using (TextReader TextReader = new StringReader(StringXML))
            {
                Result = (T)XmlSerializer.Deserialize(TextReader);
            }
            return Result;
        }
    }

Essas são as classes que representam meu xml. Repare nos atributos que decoram essa classe. Eles tem os mesmos nomes dos elementos do xml.

[XmlRoot("Pages")]
    public sealed class Pages
    {
        [XmlElement("Page")]
        public List<Page> Items { get; set; }

        public Pages() 
        {
            Items = new List<Page>(); 
        }
    }
    public sealed class Page
    {
        [XmlElement("Name")]
        public string Name { get; set; }
        [XmlElement("Url")]
        public string Url { get; set; }
        [XmlElement("XPathExpression")]
        public string XPathExpression { get; set; }
    }

Usage example:

Upload xml

UtilXML.LoadXMLByPath(@"C:\temp\Pages.xml");

Deserialize to the Pages class.

Pages = this.UtilXML.DeserializeFromXml<Pages>(this.UtilXML.XmlDocument.InnerXml);

Expecting to be relevant, if the problem is related to an empty value there is an alternative. Create an extension method.

Create a class with methods like this

public static class MetodosExtensao
{
    public static string ElementValueOrEmpty(this XElement element)
    {
        if (element != null)
            return element.Value;

        return "";
    }
}

In this case it is the reading of a String, I make one for each type of item.

In the class that will read xml add the class as the extension methods

using MetodosExtensao;

and the XML reading will be as below:

XDocument r; //aqui irá receber o xml     
IList<Classe> Lista = (from retorno in r.Descendants("Data").Elements("values")
                                                 select new Classe
                                                 {
                                                     nome = retornoBusca.Element("nome").ElementValueOrEmpty()
                                                 }).ToList();

That's it. This is the procedure I use, I'm a beginner so I'm sorry for some error in the response or in the code.

It is almost certain that the xml variable is null for some reason. Consider validating the value of it before using it to instantiate the XDocument object.