Once a programmer decides to implement IXmlSerializable
, what are the rules and best practices for implementing it? I've heard that GetSchema()
should return null
and ReadXml
should move to the next element before returning. Is this true? And what about WriteXml
– should it write a root element for the object or is it assumed that the root is already written? How should child objects be treated and written?
Here's a sample of what I have now. I'll update it as I get good responses.
public class MyCalendar : IXmlSerializable
{
private string _name;
private bool _enabled;
private Color _color;
private List<MyEvent> _events = new List<MyEvent>();
public XmlSchema GetSchema() { return null; }
public void ReadXml(XmlReader reader)
{
if (reader.MoveToContent() == XmlNodeType.Element && reader.LocalName == "MyCalendar")
{
_name = reader["Name"];
_enabled = Boolean.Parse(reader["Enabled"]);
_color = Color.FromArgb(Int32.Parse(reader["Color"]));
if (reader.ReadToDescendant("MyEvent"))
{
while (reader.MoveToContent() == XmlNodeType.Element && reader.LocalName == "MyEvent")
{
MyEvent evt = new MyEvent();
evt.ReadXml(reader);
_events.Add(evt);
}
}
reader.Read();
}
}
public void WriteXml(XmlWriter writer)
{
writer.WriteAttributeString("Name", _name);
writer.WriteAttributeString("Enabled", _enabled.ToString());
writer.WriteAttributeString("Color", _color.ToArgb().ToString());
foreach (MyEvent evt in _events)
{
writer.WriteStartElement("MyEvent");
evt.WriteXml(writer);
writer.WriteEndElement();
}
}
}
public class MyEvent : IXmlSerializable
{
private string _title;
private DateTime _start;
private DateTime _stop;
public XmlSchema GetSchema() { return null; }
public void ReadXml(XmlReader reader)
{
if (reader.MoveToContent() == XmlNodeType.Element && reader.LocalName == "MyEvent")
{
_title = reader["Title"];
_start = DateTime.FromBinary(Int64.Parse(reader["Start"]));
_stop = DateTime.FromBinary(Int64.Parse(reader["Stop"]));
reader.Read();
}
}
public void WriteXml(XmlWriter writer)
{
writer.WriteAttributeString("Title", _title);
writer.WriteAttributeString("Start", _start.ToBinary().ToString());
writer.WriteAttributeString("Stop", _stop.ToBinary().ToString());
}
}
Corresponding Sample XML
<MyCalendar Name="Master Plan" Enabled="True" Color="-14069085">
<MyEvent Title="Write Code" Start="-8589241828854775808" Stop="-8589241756854775808" />
<MyEvent Title="???" Start="-8589241828854775808" Stop="-8589241756854775808" />
<MyEvent Title="Profit!" Start="-8589247048854775808" Stop="-8589246976854775808" />
</MyCalendar>
Best Answer
Yes, GetSchema() should return null.
For both read and write, the object element has already been written, so you don't need to add an outer element in write. For example, you can just start reading/writing attributes in the two.
For write:
And for read:
I'll agree that is a little unclear, but it boils down to "it is your job to
Read()
the end-element tag of the wrapper".