Bug 21072 - DataContractSerializer does not serialize enum flags the same as .net 4
Summary: DataContractSerializer does not serialize enum flags the same as .net 4
Alias: None
Product: Class Libraries
Classification: Mono
Component: WCF assemblies ()
Version: unspecified
Hardware: PC Windows
: --- normal
Target Milestone: Untriaged
Assignee: marcos.henrich
Depends on:
Reported: 2014-07-03 02:26 UTC by Chris Turner
Modified: 2014-11-27 18:30 UTC (History)
3 users (show)

Is this bug a regression?: ---
Last known good build:

Notice (2018-05-24): bugzilla.xamarin.com is now in read-only mode.

Please join us on Visual Studio Developer Community and in the Xamarin and Mono organizations on GitHub to continue tracking issues. Bugzilla will remain available for reference in read-only mode. We will continue to work on open Bugzilla bugs, copy them to the new locations as needed for follow-up, and add the new items under Related Links.

Our sincere thanks to everyone who has contributed on this bug tracker over the years. Thanks also for your understanding as we make these adjustments and improvements for the future.

Please create a new report on GitHub or Developer Community with your current version information, steps to reproduce, and relevant error messages or log files if you are hitting an issue that looks similar to this resolved bug and you do not yet see a matching new report.

Related Links:

Description Chris Turner 2014-07-03 02:26:59 UTC
give an enum flags 

    public enum PortalNotifications
        None = 0,
        TardyAlerts = 0x10,
        IncidentAlerts = 0x20,
        All = 0xffff,
        UseCurrent = 0x10000

public class DeviceNotifications
      public PortalNotifications NotificationsType = PortalNotifications.All;

.net 4 when serializing the value PortalNotifications.All will generate a single entry in the xml
<NotificationsType xmlns="http://schemas.datacontract.org/2004/07/PSRMWebService.Model.Version1">All</NotificationsType>

Xamarin datacontractserializer will serialize all applicable flag values
<NotificationsType xmlns:d2p1="http://schemas.datacontract.org/2004/07/PSRMWebService.Model.Version1">None TardyAlerts IncidentAlerts All</NotificationsType>

I assume the .net 4 one looks for exact matches first.

below is the code we use to do the serialization. On the server the deserialization is done automatically via MVC webapi
    protected void SerializeToString(object Data, Type DataType, out int DataLength, out string DataString)
            DataLength = 0;
            using (var MS = new MemoryStream())
                // default text encoding is UTF-8 apparently
                DataContractSerializer ser = new DataContractSerializer(DataType);
                ser.WriteObject(MS, Data);

 		byte[] Buffer = MS.ToArray();
		long Length = Buffer.LongLength;

		// the length parameter is becuase the buffer is a set size...
                DataString = Encoding.UTF8.GetString( Buffer, 0, (int) Length );

		// this looks hokey, it is, the datacontractserlializer is supposed to default to utf-8 but
		// some builds of monotuch it puts a double byte mark at the start. so we remove it otherwise
		// it wont deseaerlize
		if ( (int) DataString[0] > 65000 )
		    DataString = DataString.Substring( 1 );

		DataLength = DataString.Length;

hopefully this is readable enough. We are basically using the standard datacontractserializer and writing it to a memorystream.
Comment 1 Chris Turner 2014-07-08 19:01:06 UTC
the .net enum encoder always seems to look for an exact match in flags first, then it looks for partial matches.
Comment 2 marcos.henrich 2014-11-27 08:09:36 UTC
Hi Chris,

Thank you for the detailed bug report.

The pull request for this issue can be found in the link below.