KeyAttribute Class
Microsoft Silverlight will reach end of support after October 2021. Learn more.
Specifies one or more entity properties to use as the unique identity for the entity.
Inheritance Hierarchy
System.Object
System.Attribute
System.ComponentModel.DataAnnotations.KeyAttribute
Namespace: System.ComponentModel.DataAnnotations
Assembly: System.ComponentModel.DataAnnotations (in System.ComponentModel.DataAnnotations.dll)
Syntax
'Declaration
<AttributeUsageAttribute(AttributeTargets.Property Or AttributeTargets.Field, AllowMultiple := False, _
Inherited := True)> _
Public NotInheritable Class KeyAttribute _
Inherits Attribute
[AttributeUsageAttribute(AttributeTargets.Property|AttributeTargets.Field, AllowMultiple = false,
Inherited = true)]
public sealed class KeyAttribute : Attribute
The KeyAttribute type exposes the following members.
Constructors
| Name | Description | |
|---|---|---|
.gif "Public method") |
KeyAttribute | Initializes a new instance of the KeyAttribute class. |
Top
Methods
| Name | Description | |
|---|---|---|
|
Equals | Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.) |
.gif "Protected method") |
Finalize | Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.) |
|
GetHashCode | Returns the hash code for this instance. (Inherited from Attribute.) |
|
GetType | Gets the Type of the current instance. (Inherited from Object.) |
|
Match | When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.) |
|
MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
|
ToString | Returns a string that represents the current object. (Inherited from Object.) |
Top
Remarks
You apply the KeyAttribute attribute to one or more properties to specify the values that uniquely identify the entity object.
Examples
The following example shows a KeyAttribute applied to a property named ProductID that uniquely identifies the individual data records represented by this class.
Public Class Product
<Key()> _
Public Property ProductID As Integer
'Implement Get and Set logic
End Property
End Class
public class Product
{
[Key]
public integer ProductID { get; set; }
}
Version Information
Silverlight
Supported in: 5, 4, 3
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.
Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
See Also