C# XML deserialize self closing raw element

Question

I need to process some XML input which has HTML code in some tags. For these tags I want the raw content to process it later. I followed this answer and used XmlElement which works fine in most cases. The only problem I'm facing are self closing tags.

[Serializable]
public class Root
{
    public XmlElement Description { get; set; }
    public string Name { get; set; }
}

var serializer = new XmlSerializer(typeof(Root));

var obj1 = serializer.Deserialize(new StringReader(@"<Root><Description><p>test</p></Description><Name>Test</Name></Root>"));
// Description: "Element, Name=\"p\""
// Name: "Test"

var obj2 = serializer.Deserialize(new StringReader(@"<Root><Description></Description><Name>Test</Name></Root>"));
// Description: null
// Name: "Test"

var obj3 = serializer.Deserialize(new StringReader(@"<Root><Description/><Name>Test</Name></Root>"));
// Description: "Element, Name=\"Name\""
// Name: null

obj1 and obj2 are ok (obj2.Description == "" would be better) but in obj3 the Description member is greedy and contains the Name part.

Is there a workaround for this problem?

I genuinely didn't expect this to repro, but it does; so ... yeah, looks like a bug in XmlSerializer, and would need to be fixed there! — Marc Gravell, Jan 16 '23 at 13:24
Thank you, I opened an issue https://github.com/dotnet/runtime/issues/80699 — Janis E., Jan 16 '23 at 14:30

score 1 · Answer 1 · answered Jan 16 '23 at 13:47

A possible workaround is to declare a custom class for the Description property, matching any content inside the element using the [XmlAnyElement] attribute:

public class Root
{
    public Description Description { get; set; }

    public string Name { get; set; }
}


public class Description
{
    [XmlAnyElement]
    public List<XmlElement> Content { get; set; }
}

The only drawback is this won't work for mixed content. In other words, this will deserialize well:

<Description><p>test</p></Description>

but this won't, deserializing the <span> only:

<Description>some <span>other</span> text</Description>

Should you need mixed content, implement IXmlSerializable on the Description class.

However, it does work for <Description/>. That being said, I do agree with @MarcGravell that it's a bug in XmlSerializer and shall be reported.

score 1 · Answer 2 · answered Jan 16 '23 at 14:50

As suggested I reported this issue.

I use this code now to workaround the issue:

using System;
using System.IO;
using System.Xml;
using System.Xml.Serialization;
using System.Xml.Schema;
                    
public class Program
{
    public static void Main()
    {
        var serializer = new XmlSerializer(typeof(Root));

        var obj1 = serializer.Deserialize(new StringReader(@"<Root><Description><p>test</p></Description><Name>Test</Name></Root>"));
        Console.WriteLine(obj1); // Description: <p>test</p> / Name: Test

        var obj2 = serializer.Deserialize(new StringReader(@"<Root><Description></Description><Name>Test</Name></Root>"));
        Console.WriteLine(obj2); // Description:  / Name: Test

        var obj3 = serializer.Deserialize(new StringReader(@"<Root><Description/><Name>Test</Name></Root>"));
        Console.WriteLine(obj3); // Description:  / Name: Test
    }

    public class Root
    {
        public HtmlElement Description { get; set; }
        public string Name { get; set; }
        
        public override string ToString() => $"Description: {Description.Content} / Name: {Name}";
    }
    
    public class HtmlElement : IXmlSerializable
    {
        public string Content { get; set; } = "";

        public XmlSchema GetSchema() => null;

        public void ReadXml(XmlReader reader)
        {
            reader.MoveToContent();

            if (!reader.IsEmptyElement && reader is XmlTextReader xtr)
            {
                Content = xtr.ReadInnerXml();
            }
        }

        public void WriteXml(XmlWriter writer) => throw new NotImplementedException();
    }
}

C# XML deserialize self closing raw element

2 Answers2