How can I XML Serialize a DateTimeOffset Property?

Question

The DateTimeOffset property I have in this class doesn't get rendered when the data is represented as Xml. What do I need to do to tell the Xml serialization to render that proper as a DateTime or DateTimeOffset?

[XmlRoot("playersConnected")] public class PlayersConnectedViewData {     [XmlElement("playerConnected")]     public PlayersConnectedItem[] playersConnected { get; set; } }  [XmlRoot("playersConnected")] public class PlayersConnectedItem {     public string name { get; set; }     public DateTimeOffset connectedOn { get; set; }  // <-- This property fails.     public string server { get; set; }     public string gameType { get; set; } } 

and some sample data...

<?xml version="1.0" encoding="utf-8"?> <playersConnected       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"      xmlns:xsd="http://www.w3.org/2001/XMLSchema">   <playerConnected>     <name>jollyroger1000</name>     <connectedOn />     <server>log1</server>     <gameType>Battlefield 2</gameType>   </playerConnected> </playersConnected> 

Update

I'm hoping there might be a way through an Attribute which I can decorate on the property...

Bonus Question

Any way to get rid of those two namespaces declared in the root node? Should I?

Answer 1

It's a few years late, but here's the quick and easy way to completely serialize DateTimeOffset using ISO 8601:

[XmlElement("lastUpdatedTime")] public string lastUpdatedTimeForXml // format: 2011-11-11T15:05:46.4733406+01:00 {    get { return lastUpdatedTime.ToString("o"); } // o = yyyy-MM-ddTHH:mm:ss.fffffffzzz    set { lastUpdatedTime = DateTimeOffset.Parse(value); }  } [XmlIgnore]  public DateTimeOffset lastUpdatedTime; 

Answer 2

I came up with this struct which implements XML serialization based on ISO 8601 formatting (e.g. 2011-11-11T15:05:46.4733406+01:00). Hint: Trying to parse a DateTime value such as 2011-11-11T15:05:46 fails as expected.

Feedback welcome. I didn't include the unit tests here because that would be too much text.

/// <remarks> /// The default value is <c>DateTimeOffset.MinValue</c>. This is a value /// type and has the same hash code as <c>DateTimeOffset</c>! Implicit /// assignment from <c>DateTime</c> is neither implemented nor desirable! /// </remarks> public struct Iso8601SerializableDateTimeOffset : IXmlSerializable {     private DateTimeOffset value;      public Iso8601SerializableDateTimeOffset(DateTimeOffset value)     {         this.value = value;     }      public static implicit operator Iso8601SerializableDateTimeOffset(DateTimeOffset value)     {         return new Iso8601SerializableDateTimeOffset(value);     }      public static implicit operator DateTimeOffset(Iso8601SerializableDateTimeOffset instance)     {         return instance.value;     }      public static bool operator ==(Iso8601SerializableDateTimeOffset a, Iso8601SerializableDateTimeOffset b)     {         return a.value == b.value;     }      public static bool operator !=(Iso8601SerializableDateTimeOffset a, Iso8601SerializableDateTimeOffset b)     {         return a.value != b.value;     }      public static bool operator <(Iso8601SerializableDateTimeOffset a, Iso8601SerializableDateTimeOffset b)     {         return a.value < b.value;     }      public static bool operator >(Iso8601SerializableDateTimeOffset a, Iso8601SerializableDateTimeOffset b)     {         return a.value > b.value;     }      public override bool Equals(object o)     {         if(o is Iso8601SerializableDateTimeOffset)             return value.Equals(((Iso8601SerializableDateTimeOffset)o).value);         else if(o is DateTimeOffset)             return value.Equals((DateTimeOffset)o);         else             return false;     }      public override int GetHashCode()     {         return value.GetHashCode();     }      public XmlSchema GetSchema()     {         return null;     }      public void ReadXml(XmlReader reader)     {         var text = reader.ReadElementString();         value = DateTimeOffset.ParseExact(text, format: "o", formatProvider: null);     }      public override string ToString()     {         return value.ToString(format: "o");     }      public string ToString(string format)     {         return value.ToString(format);     }      public void WriteXml(XmlWriter writer)     {         writer.WriteString(value.ToString(format: "o"));     } }