MetadataTypeAttribute Class
 

Specifies the metadata class to associate with a data model class.

Namespace:   System.ComponentModel.DataAnnotations
Assembly:  System.ComponentModel.DataAnnotations (in System.ComponentModel.DataAnnotations.dll)

SystemObject
   SystemAttribute
    System.ComponentModel.DataAnnotationsMetadataTypeAttribute

[AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple = false)]
public sealed class MetadataTypeAttribute : Attribute
[AttributeUsageAttribute(AttributeTargets::Class, AllowMultiple = false)]
public ref class MetadataTypeAttribute sealed : Attribute
[<Sealed>]
[<AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple = false)>]
type MetadataTypeAttribute = 
    class
        inherit Attribute
    end
<AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple := False)>
Public NotInheritable Class MetadataTypeAttribute
	Inherits Attribute
NameDescription
System_CAPS_pubmethod MetadataTypeAttribute

Initializes a new instance of the MetadataTypeAttribute class.

NameDescription
System_CAPS_pubproperty

Gets the metadata class that is associated with a data-model partial class.

System_CAPS_pubproperty

When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)

NameDescription
System_CAPS_pubmethod Equals

This API supports the product infrastructure and is not intended to be used directly from your code. Returns a value that indicates whether this instance is equal to a specified object.(Inherited from Attribute.)

System_CAPS_pubmethod GetHashCode

Returns the hash code for this instance.(Inherited from Attribute.)

System_CAPS_pubmethod GetType

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethod IsDefaultAttribute

When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)

System_CAPS_pubmethod Match

When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)

System_CAPS_pubmethod ToString

Returns a string that represents the current object.(Inherited from Object.)

NameDescription
System_CAPS_pubinterface System_CAPS_privmethod _AttributeGetIDsOfNames

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterface System_CAPS_privmethod _AttributeGetTypeInfo

Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.)

System_CAPS_pubinterface System_CAPS_privmethod _AttributeGetTypeInfoCount

Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterface System_CAPS_privmethod _AttributeInvoke

Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

The MetadataTypeAttribute attribute enables you to associate a class with a data-model partial class. In this associated class you provide additional metadata information that is not in the data model.

For example, in the associated class you can apply the RequiredAttribute attribute to a data field. This enforces that a value is provided for the field even if this constraint is not required by the database schema.

You use the MetadataTypeAttribute attribute as follows:

  • In your application, create a file in which you create the data-model partial class that you want to modify.

  • Create the associated metadata class.

  • Apply the MetadataTypeAttribute attribute to the partial entity class, specifying the associated class.

When you apply this attribute, you must adhere to the following usage constraints:

  • The attribute can only be applied to a class.

  • The attribute cannot be inherited by derived classes.

  • The attribute can be applied only one time.

The following example shows how to use the MetadataTypeAttribute to associate a metadata class with an entity partial class. The example applies the RequiredAttribute attribute to a data field to show how to provide additional information in the associated metadata class.

using System;
using System.Web.DynamicData;
using System.ComponentModel.DataAnnotations;

[MetadataType(typeof(CustomerMetaData))]
public partial class Customer
{


}


public class CustomerMetaData
{
    // Apply RequiredAttribute
    [Required(ErrorMessage = "Title is required.")]
    public object Title;


}
Imports System
Imports System.Web.DynamicData
Imports System.ComponentModel.DataAnnotations

<MetadataType(GetType(CustomerMetadata))> _
Partial Public Class Customer

End Class

Public Class CustomerMetadata

    ' Apply RequitedAttribute.
    <Required(ErrorMessage:="Title is required.")> _
    Public Title As Object


End Class
.NET Framework
Available since 3.5

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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