Version tolerant XML Serialization - wpf

Question

Reader C# project need to persists ~POCO to file. But we are at our debut and changes occurs quite often. Our soft is already used (persisted) by few customers.
I prefer to use XML over anything for many reasons.
I checked many many xml serialization libs.
Many libs stores the specific type and version. I don’t need that.
Many libs do not give us the possibility to serialize by ourself: ie we need an interface to custom load/save data (I see many advantages **)
Some libs forces us to have empty constructor
Some libs only manage public properties
Some libs have many limitations on types (do not support Dictionary, …)
** (advantages of an interface to load/save data)
Easier to manage many versions
Enable to do hardcoded conversion if required (class x -> class y, … )
Easier to not retain old code
I strongly think that for my needs we would better served by using the old way: a bit like deserializing in C++. I think we would be better served by something that would enable us to just add fields and fields name manually instead of using Attributes.
Kind of:
void XmlDeserialize(XmlReader xmlReader)
{
xmlReader.Load((n)=>Version(n)); // or just: _version = xmlReader.LoadInt("Version");
xmlReader.Load((n)=>Name(n));
xmlReader.Load((n)=>EmployeeId(n));
if (Version ==2)
…
If (version == 3)
…
The closest I have found to fit my needs was: DataContractSerializer that supports IExtensibleDataObject, but it is a pain and ass to use.
I question myself if I’m not wrong everywhere? It’s impossible I’m the only one with that need (or this vision). Why is nobody writing any lib for that, and did I miss something somewhere ?
What I think wrongly ? What do you recommend ?

Answer 1

Do you have to use XML reader.load for this? It is WAY easier to create the business objects that represent your XML data, and then deserialize the object, like below (sorry I only found my vb.net version of this):
Public Shared Function ReadFromString(ByVal theString As String, ByVal encoding As System.Text.Encoding, ByVal prohibitDTD As Boolean) As T
Dim theReturn As T = Nothing
Dim s As System.Xml.Serialization.XmlSerializer
s = New System.Xml.Serialization.XmlSerializer(GetType(T))
Dim theBytes As Byte() = encoding.GetBytes(theString)
Using ms As New IO.MemoryStream(theBytes)
Using sTr As New StreamReader(ms, encoding)
Dim sttng As New XmlReaderSettings
'sttng.ProhibitDtd = prohibitDTD
If Not prohibitDTD Then
sttng.DtdProcessing = DtdProcessing.Ignore
sttng.XmlResolver = Nothing
Else
sttng.DtdProcessing = DtdProcessing.Prohibit
End If
Using r As XmlReader = XmlReader.Create(sTr, sttng)
theReturn = CType(s.Deserialize(r), T)
End Using
End Using
End Using
Return theReturn
End Function
You can event get rid of the xmlreadersettings and the encoding if you like. But this way you could keep different business objects for each version you have? Additionally, if you're only adding (and not changing/deleting) objects, you can still use the most recent business object for all versions, and just ignore the missing fields.

Answer 2

I finally decided to use XmlSerialization like this
usage but I hate to be forced to create default constructor and not being able to serialize members (private or public).
I also decided to use ProtoContract when very high speed is necessary.
But my preferred one is DataContractSerializer where it offer xml format (easier to debug), no default constructor needed and can serialize any members.