Question

In addition to a list of objects I am serializing to an xml file using C#’s XmlSerializer, I would like to store a few more independent elements (mainly strings from textboxes) in the same xml.

    public static void SaveBehaviors(ObservableCollection<Param> listParams)
    {
        XmlSerializer _paramsSerializer = new XmlSerializer(listParams.GetType());
        string path = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
        path += "\\test.xml";
        using (TextWriter writeFileStream = new StreamWriter(path))
        {
            _paramsSerializer.Serialize(writeFileStream, listParams);

            using (XmlWriter writer = XmlWriter.Create(writeFileStream))
            {
                writer.WriteStartElement("Foo"); //test entry...
                writer.WriteAttributeString("Bar", "Some & value");
                writer.WriteElementString("Nested", "data");
                writer.WriteEndElement();
            }
        }
    }

However, deserializing “test.xml” results in an error because of the added element. I suppose writing in the serialized xml file is prohibited and should be avoided?

Answer 1

No. Don’t do that.

If you need to serialize more than your ObservableCollection, then define a containing type and serialize that.

public static void SaveBehaviors(ObservableCollection<Param> listParams) 
{ 
    XmlSerializer _paramsSerializer = new XmlSerializer(typeof(ContainingType)); 
    var c = new ContainingType(listParams); 
    c.ExtraInformation = whatever....; 

    string path = Environment.GetFolderPath(Environment.SpecialFolder.Desktop); 
    path += "\\test.xml"; 
    using (TextWriter writeFileStream = new StreamWriter(path)) 
    { 
        _paramsSerializer.Serialize(writeFileStream, c); 
    } 
} 

Use the XmlSerializer.