//Workaround for bug report: https://github.com/dotnet/runtime/issues/44701 (issue shown at https://dotnetfiddle.net/W9zCSm)

//Using XmlAttributeOverrides as suggested at https://social.msdn.microsoft.com/Forums/vstudio/en-US/4d70a9b9-0546-478b-8fd1-becee107106a/xmlserializer-fails-when-trying-to-serialize-hidden-property-with-xmlignore

​

using System;

using System.Xml;

using System.Xml.Serialization;

using System.Runtime.Serialization;

using System.IO;

using System.Text;

​

public class Program

{

    public static void Main()

    {

        XmlAttributeOverrides overrides = new XmlAttributeOverrides();

​

        //Override hiding of members (workarround for XmlIgnore being ignore if defined at descendant class)

        //Override order for of members (without this you get E,G,C,D output order)

        overrides.Add(typeof(ToSerialize), "A", new XmlAttributes { XmlIgnore = true, XmlElements = { new XmlElementAttribute(){ Order=1 } } });

        overrides.Add(typeof(ToSerialize), "B", new XmlAttributes { XmlIgnore = true, XmlElements = { new XmlElementAttribute(){ Order=2 } } });

        overrides.Add(typeof(ToSerialize), "C", new XmlAttributes { XmlIgnore = false, XmlElements = { new XmlElementAttribute(){ Order=3 } } } );

        overrides.Add(typeof(ToSerialize), "G", new XmlAttributes { XmlIgnore = false, XmlAnyElements = { new XmlAnyElementAttribute(){ Order=4 } } } );

        overrides.Add(typeof(ToSerialize), "D", new XmlAttributes { XmlIgnore = false, XmlElements = { new XmlElementAttribute(){ Order=5 } } } );

        overrides.Add(typeof(ToSerialize), "H", new XmlAttributes { XmlIgnore = false, XmlAnyElements = { new XmlAnyElementAttribute(){ Order=6 } } } );

        overrides.Add(typeof(ToSerialize), "E", new XmlAttributes { XmlIgnore = false, XmlElements = { new XmlElementAttribute(){ Order=7 } } } );

        using(var stream = new MemoryStream()){

            XmlSerializer xmlSer = new XmlSerializer(typeof(ToSerializeA), overrides); //typeof(ToSerialize)

            xmlSer.Serialize(

                stream,

                //new ToSerialize(){}

                new ToSerializeA(){ NoExtraComment = true } //set to false to show the extra comment for H (note that we've set XmlIgnore=false, but can still return an XmlComment or XmlSignificantWhitespace based on this flag)

            );

            stream.Position = 0;

            using (var reader = new StreamReader(stream, Encoding.UTF8))

            {

                string value = reader.ReadToEnd();

                Console.WriteLine(value);

            }

        }

    }

}

​

[Serializable]

public partial class ToSerialize

{

    public const string MSG_SERIALIZABLE = "Serializable";

    public const string MSG_NON_SERIALIZABLE = "Non-Serializable";  

    public string A { get; set;} = MSG_SERIALIZABLE;

    public virtual string B { get; set;} = MSG_SERIALIZABLE;

    [XmlIgnore]

    public string C { get; set;} = MSG_NON_SERIALIZABLE;

    [XmlIgnore]

    public virtual string D { get; set;} = MSG_NON_SERIALIZABLE;

}

​

public partial class ToSerialize

{

    [XmlIgnore]

    public bool NoExtraComment = false;

    public string E { get; set;} = MSG_SERIALIZABLE;

    [XmlIgnore]

    public string F { get; set;} = MSG_NON_SERIALIZABLE;

    [XmlAnyElement(nameof(G))] //better have a name at XmlAnyElement, else WCF's serialization chokes on it even with every possible ignore attribute being used

    [XmlIgnore, SoapIgnore, IgnoreDataMember] //to be overriden so that comment gets shown

    public XmlCharacterData G {

        get { return new XmlDocument().CreateComment("G (Comment)"); }

        set {} //this is required, if missed it won't emit the comment

    }

    [XmlAnyElement(nameof(H))] //better have a name at XmlAnyElement, else WCF's serialization chokes on it even with every possible ignore attribute being used

    [XmlIgnore, SoapIgnore, IgnoreDataMember] //not needed to ignore even via an AttributeOverride, will hide by returning a SignificantWhiteSpace //keeping it for other serialization clients

    public XmlCharacterData H {

        get {

            return !NoExtraComment?

                new XmlDocument().CreateComment("H (Comment)") :

                new XmlDocument().CreateSignificantWhitespace("");

                    } //No comment

        set {} //if this doesn't exists it will just be ignored

    }

​

}

​

//-----------------------------------------

​

[Serializable]

public class ToSerializeA: ToSerialize

{

    [XmlIgnore]

    public new string A { get; set;} = MSG_NON_SERIALIZABLE; //BUG: SHOULDN'T SERIALIZE THIS

    [XmlIgnore]

    public override string B { get; set;} = MSG_NON_SERIALIZABLE; //BUG: SHOULDN'T SERIALIZE THIS

​

    public new string C { get; set;} = MSG_SERIALIZABLE;

    public override string D { get; set;} = MSG_SERIALIZABLE;

}

​