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Using Entity Framework Self Tracking Entities with Workflow Persistence in .NET 4.0 RC

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I just ran into a problem when trying to use Workflow Persistence with Self Tracking Entities in .NET 4.0 RC.

The execution of the InstancePersistenceCommand named {urn:schemas-microsoft-com:System.Activities.Persistence/command}SaveWorkflow was interrupted by a
n error. ---> System.Runtime.Serialization.InvalidDataContractException: Type ‘ElasticSoftware.DownloadSheriff.Domain.Model.Entities.TrackableCollection`1[ElasticSoftware.DownloadSheriff.Domain.Model.Entities.Customer]' cannot be serialized. Consider marking it with the DataContractAttribute attribute, and marking all of its members you want serialized with the DataMemberAttribute attribute.  If the type is a collection, consider marking it with the CollectionDataContractAttribute.  See the Microsoft .NET Framework documentation for other supported types.

By Default the TrackableCollection in the Types.tt is not annotated with a DataContract attribute.

You can fix this by going to Line 1401 and adding the DataContract attribute like so: 

[DataContract]
public class TrackableCollection<T> : ObservableCollection<T>

Then regenerate from your T4 templates and you should be good to go.