XmlSerializer again

  • Thread starter Thread starter The Last Danish Pastry
  • Start date Start date
T

The Last Danish Pastry

Why is it that I can serialize a DateTime using XmlSerializer, but not
a TimeSpan?

Also, and perhaps more importantly - how could I have known ahead of
time, using the published documentation, that DateTime is going to
work and TimeSpan isn't?

Trying to serialize a TimeSpan does not throw any exceptions or
trigger any events.

Here is some code that produces two files of xml...
=========================================
private void button1_Click(object sender, EventArgs e)
{
{
DateTime testObject = new DateTime(2000, 12, 25, 1, 2, 3);
XmlSerializer xs = new XmlSerializer(testObject.GetType());
StreamWriter sw = new StreamWriter(@"c:\qaz\DateTime.xml");
xs.Serialize(sw, testObject);
sw.Close();
}
{
TimeSpan testObject = new TimeSpan(1, 2, 3, 4, 5);
XmlSerializer xs = new XmlSerializer(testObject.GetType());
StreamWriter sw = new StreamWriter(@"c:\qaz\TimeSpan.xml");
xs.Serialize(sw, testObject);
sw.Close();
}
} // button1_Click
=========================================

c:\qaz\DateTime.xml can be used to correctly deserialize the original
DateTime object.
The file c:\qaz\DateTime.xml...
=========================================
<?xml version="1.0" encoding="utf-8"?>
<dateTime>2000-12-25T01:02:03</dateTime>
=========================================

c:\qaz\TimeSpan.xml contains no information about the TimeSpan object,
which thus cannot be deserialized.
The file c:\qaz\TimeSpan.xml...
=========================================
<?xml version="1.0" encoding="utf-8"?>
<TimeSpan xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema" />
=========================================
 
Since you've asked this, what, 3 times - I think we can assume that
nobody has a satisfactory answer.

Yes it is a known issue; it has been there a while. You could log a
bug on connect.microsoft.com to see if anybody there says anything
useful, or you could work around it - by either exposing this as a
DateTime (only using the TimeOfDay part), an integer (the minutes /
seconds / whatever resolution you need) or as a string.

Not great, but that is how it is at time moment via XmlSerializer.

Mar
 
The Last Danish Pastry said:
Why is it that I can serialize a DateTime using XmlSerializer, but not
a TimeSpan?
Click to expand...

Afraid can't help with the actual problem, but you can circumvent it by
using long. TimeSpan uses it for ticks so you get the value back without too
much hassle.
 
Since you've asked this, what, 3 times - I think we can assume that
nobody has a satisfactory answer.

Yes it is a known issue; it has been there a while. You could log a
bug on connect.microsoft.com to see if anybody there says anything
useful, or you could work around it - by either exposing this as a
DateTime (only using the TimeOfDay part), an integer (the minutes /
seconds / whatever resolution you need) or as a string.

Not great, but that is how it is at time moment via XmlSerializer.
Click to expand...

Thank you for that - and I sincerely apologise for the multiple
postings.

As it happens, I am not really interested in serializing a TimeSpan
struct. Rather I am trying to write a serialize utility class (which
uses XmlSerializer as the underlying serializer).

One method which I would like to write is a "Can you serialize that
object?" method.

I have made some progress with the DateTime/TimeSpan question...

Using reflection I can find out information about those two structs.

In particular, the interfaces which they implement...

The 6 interfaces of DateTime:
System.IComparable
System.IFormattable
System.IConvertible
System.Runtime.Serialization.ISerializable
System.IComparable`1[System.DateTime]
System.IEquatable`1[System.DateTime]

The 3 interfaces of TimeSpan:
System.IComparable
System.IComparable`1[System.TimeSpan]
System.IEquatable`1[System.TimeSpan]

So, TimeSpan does not implement
System.Runtime.Serialization.ISerializable, despite having

IsSerializable=true

and

Attributes={Public, SequentialLayout, Sealed, Serializable,
BeforeFieldInit}

So, maybe I can yet write my "Can you serialize that object?" method.
 
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