Why doesn't XmlSerializer work for shared class variables? - vb.net

Question

I have the following class which I want to serialize to XML:
<Serializable()> _
Public Class Settings
Public Shared var1 As Boolean = False
Public var2 As Boolean = False
End Class
I create a new instance and serialize it using my own method...
SaveSerialXML(PathToFile, New Settings, GetType(Settings))
...however the shared (static) variable is not included in the output:
<?xml version="1.0" encoding="utf-8"?>
<Settings>
<var2>false</var2>
</Settings>
Does anyone know of a way to serialize shared members of a class to XML?

Answer 1

Serialization is about serializing instances. Shared variables do not belong to an instance.

Answer 2

You can cheat add a redirect instance property for serialization.
For example:
Public Property Var1Instance As Boolean
Get
Return Var1
End Get
Set(value As Boolean)
Var1 = value
End Set
End Property

Answer 3

I've often found myself wanting to implement my own Xml serialization and not use the .NET XmlSerializer.
I do so by adding an Xml property to my class that directly handles the serialization via Xml Literals. That property could be a String or an XElement depending on how I'm going to use it.
Here's how the Xml String property would look for your sample class:
Public Property Xml() As String
Get
Return <Settings>
<var1><%= var1 %></var1>
<var2><%= var2 %></var2>
</Settings>.ToString
End Get
Set(ByVal value As String)
Dim xValue = XElement.Parse(value)
var1 = xValue...<var1>.Value = "true"
var2 = xValue...<var2>.Value = "true"
End Set
End Property
This places all the serialization logic in one place and avoids the use of attributes to control how an instance gets serialized. The other benefit I've found is that this allows me to deserialize a class that does not have a default constructor.
In production scenarios I would add an extension method that converts a String to a Boolean instead of comparing to "true" since valid Xml Boolean values include true, false, 1 and 0.