IDeserializationCallback
It is helpful to think of deserialization as a special form of constructor
call, since the end result is a valid object reference. While the [NonSerialized]
attribute
is useful for controlling which data is stored in the serialized form of the
object or sent over the wire on a remoting call, the problem is that the fields
marked with [NonSerialized]
are not assigned meaningful
values when the constructor (i.e. the deserialization process)
finishes executing. This can result in class invariants being violated, such
as the implicit in the preceding sample, in which Age
is
intended to store the Person
’s age based on the DateOfBirth
.
One possible solution to this problem is the IDeserializationCallback
interface.
Implementing this interface on your type indicates to the runtime that you
wish to participate in the deserialization process. This interface contains
a single method, OnDeserialization
, which the runtime invokes after it has finished constructing your object, but before it returns
the fully constructed instance to the client. This method gives you a chance
to perform whatever fixups you need to inside the object, and is a way to
ensure that class invariants are preserved before clients can access the instance.
Using our sample Person
class, the IDeserializationCallback
interface
implementation might look like this:
[Serializable] public sealed class Person : IDeserializationCallback { public string Name; public DateTime DateOfBirth; [NonSerialized] public ...
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