c# - How to serialize a TimeSpan to XML

Question

I am trying to serialize a .NET TimeSpan object to XML and it is not working. A quick google has suggested that while TimeSpan is serializable, the XmlCustomFormatter does not provide methods to convert TimeSpan objects to and from XML.

One suggested approach was to ignore the TimeSpan for serialization, and instead serialize the result of TimeSpan.Ticks (and use new TimeSpan(ticks) for deserialization). An example of this follows:

[Serializable]
public class MyClass
{
    // Local Variable
    private TimeSpan m_TimeSinceLastEvent;

    // Public Property - XmlIgnore as it doesn't serialize anyway
    [XmlIgnore]
    public TimeSpan TimeSinceLastEvent
    {
        get { return m_TimeSinceLastEvent; }
        set { m_TimeSinceLastEvent = value; }
    }

    // Pretend property for serialization
    [XmlElement("TimeSinceLastEvent")]
    public long TimeSinceLastEventTicks
    {
        get { return m_TimeSinceLastEvent.Ticks; }
        set { m_TimeSinceLastEvent = new TimeSpan(value); }
    }
}

While this appears to work in my brief testing - is this the best way to achieve this?

Is there a better way to serialize a TimeSpan to and from XML?

Answer 1

This is only a slight modification on the approach suggested in the question, but this Microsoft Connect issue recommends using a property for serialization like this:

[XmlIgnore]
public TimeSpan TimeSinceLastEvent
{
    get { return m_TimeSinceLastEvent; }
    set { m_TimeSinceLastEvent = value; }
}

// XmlSerializer does not support TimeSpan, so use this property for 
// serialization instead.
[Browsable(false)]
[XmlElement(DataType="duration", ElementName="TimeSinceLastEvent")]
public string TimeSinceLastEventString
{
    get 
    { 
        return XmlConvert.ToString(TimeSinceLastEvent); 
    }
    set 
    { 
        TimeSinceLastEvent = string.IsNullOrEmpty(value) ?
            TimeSpan.Zero : XmlConvert.ToTimeSpan(value); 
    }
}

This would serialize a TimeSpan of 0:02:45 as:

<TimeSinceLastEvent>PT2M45S</TimeSinceLastEvent>

Alternatively, the DataContractSerializer supports TimeSpan.