Unfortunately it seems that the Nullable Enums are not currently supported but this issue is already addressed and you could find it updated in a future version of Telerik OpenAccess ORM.
As a workaround you could create a wrapper property in a partial class of your Domain Class for getting and setting the Enum properly.
You could achieve this by following the steps below: 1) Change the type of the Domain Class Property to "int", set its Nullable setting to "true" and its Access Modifier to "private". 2) Create a partial class of the entity containing the Nullable enum. 3) Add a wrapper property and implement its getter and setter as below:
public MyEnum? MyEnumWrapper
{
get
{
if (this.MyEnum.HasValue)
{
return (MyEnum)this.MyEnum.Value;
}
return null;
}
set
{
this.MyEnum = (int?)value;
}
}
Regarding the mapping error that you are getting - it is a part of the OpenAccess ORM validation framework which is meant to warn you about possible inconsistencies in the model and it does not mean that your project is not buildable and it will also be fixed implementing the nullable enum support.