How to: Add Metadata Class

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How to: Add Metadata Class

Programmer's Guide > Quick-Start Scenarios > Silverlight > Silverlight 4 & 5 > WCF RIA Services > How to: Add Metadata Class

Glossary Item Box

WCF RIA Services supports the ability to annotate persistent classes and properties. Annotations are implemented with partial classes called metadata classes. You use metadata classes when you want to annotate generated persistent classes, but do not want to lose those annotations when the persistent class is regenerated. You mark the metadata class by applying the MetadataTypeAttribute attribute.

To add a metadata class manually:

In the server project, add a new class file with the same name as the persistent class that you want to annotate. By convention, include .metadata in its file name.
Add the partial keyword to make the class a partial class. The following example shows a partial class that matches the Customer persistent class from the SofiaCarRental database.

C# Copy Code

public partial class Customer
{
}

VB.NET Copy Code

Partial Public Class Customer
End Class
In the partial class, create an internal class that will serve as a metadata class. The following example shows the internal metadata class.

C# Copy Code

public partial class Customer
{
   internal sealed class CustomerMetadata
   {
   }
}

VB.NET Copy Code

Partial Public Class Customer
Friend NotInheritable Class CustomerMetadata
End Class
End Class

Add a MetadataTypeAttribute attribute to the partial class and include the type of the metadata class. The following example shows the MetadataTypeAttribute attribute applied to the class.

C#	Copy Code
[System.ComponentModel.DataAnnotations.MetadataTypeAttribute( typeof( Customer.CustomerMetadata ) )] public partial class Customer { internal sealed class CustomerMetadata { } }

VB.NET	Copy Code
<System.ComponentModel.DataAnnotations.MetadataTypeAttribute(GetType(Customer.CustomerMetadata))> Partial Public Class Customer Friend NotInheritable Class CustomerMetadata End Class End Class

In the metadata class, add properties that have the same name as the properties in the persistent class.

Copy Code

[System.ComponentModel.DataAnnotations.MetadataTypeAttribute( typeof( Customer.CustomerMetadata ) )]
public partial class Customer
{
   internal sealed class CustomerMetadata
   {
       public CustomerMetadata()
       {
       }
       public int CustomerID
       {
           get;
           set;
       }
       public string DrvLicNumber
       {
           get;
           set;
       }
       public string FullName
       {
           get;
           set;
       }
       public string Address
       {
           get;
           set;
       }
       public string Country
       {
           get;
           set;
       }
       public string City
       {
           get;
           set;
       }
       public string State
       {
           get;
           set;
       }
       public string ZIPCode
       {
           get;
           set;
       }
   }
}

VB.NET

Copy Code

<System.ComponentModel.DataAnnotations.MetadataTypeAttribute(GetType(Customer.CustomerMetadata))>
Partial Public Class Customer
Friend NotInheritable Class CustomerMetadata
  Public Sub New()
  End Sub
  Public Property CustomerID() As Integer
  Public Property DrvLicNumber() As String
  Public Property FullName() As String
  Public Property Address() As String
  Public Property Country() As String
  Public Property City() As String
  Public Property State() As String
  Public Property ZIPCode() As String
End Class
End Class

Add annotation attributes to the properties, like in the following example:

Copy Code

[MetadataTypeAttribute( typeof( Customer.CustomerMetadata ) )]
public partial class Customer
{
   internal sealed class CustomerMetadata
   {
       public CustomerMetadata()
       {
       }
       public int CustomerID
       {
           get;
           set;
       }
       [System.ComponentModel.DataAnnotations.Required]
       public string DrvLicNumber
       {
           get;
           set;
       }
       [System.ComponentModel.DataAnnotations.StringLength( 50 )]
       public string FullName
       {
           get;
           set;
       }
       [System.ComponentModel.DataAnnotations.RegularExpression( "abc" )]
       public string Address
       {
           get;
           set;
       }
       public string Country
       {
           get;
           set;
       }
       public string City
       {
           get;
           set;
       }
       public string State
       {
           get;
           set;
       }
       public string ZIPCode
       {
           get;
           set;
       }
   }
}

VB.NET

Copy Code

<MetadataTypeAttribute(GetType(Customer.CustomerMetadata))>
Partial Public Class Customer
Friend NotInheritable Class CustomerMetadata
  Public Sub New()
  End Sub
  Public Property CustomerID() As Integer
  <System.ComponentModel.DataAnnotations.Required>
  Public Property DrvLicNumber() As String
  <System.ComponentModel.DataAnnotations.StringLength(50)>
  Public Property FullName() As String
  <System.ComponentModel.DataAnnotations.RegularExpression("abc")>
  Public Property Address() As String
  Public Property Country() As String
  Public Property City() As String
  Public Property State() As String
  Public Property ZIPCode() As String
End Class
End Class

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