Indicates that a property or a field is a key.
[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field, Inherited = true)] public sealed class KeyAttribute : Attribute, _Attribute
<AttributeUsage(AttributeTargets.Property Or AttributeTargets.Field, Inherited:=True)> Public NotInheritable Class KeyAttribute Inherits Attribute Implements _Attribute
Apply this attribute to a property or a field to mark it as a key. The KeyAttribute.AutoGenerate property specifies whether the key is generated automatically.
When a key is changed for a saved object, XPO considers this object as new and inserts a new record into the database. Key properties must not be changed once a persistent object is saved. An end-user must never be allowed to change an object's key property. We recommend that you define a key property as "read-only".