Different types of Id when exposing DTO over WCF

Lets say we have a simple DTO with properties Id, Name. If this DTO comes from database through some data layer, Id should be of type int. If this DTO comes from Activ开发者_如何学Pythone Directory, through some data layer, Id should be of type Guid.

What would be the best way to implement this?

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The easiest way is to simply have two properties each of their appropriate type:

public Guid ActiveDirectoryID {get;set;};

public int DatabaseID {get;set;};

As an alternative you can define the ID property as an Object and implement it with an overloaded GetID() and SetID() for both types.

It's possible but not trivial to convert between a Guid and Int types.