Specifies the metadata class to associate with a data model class.
Assembly: System.ComponentModel.DataAnnotations (in System.ComponentModel.DataAnnotations.dll)
Thetype exposes the following members.
|Equals||Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)|
|GetHashCode||Returns the hash code for this instance. (Inherited from Attribute.)|
|GetType||Gets the Type of the current instance. (Inherited from Object.)|
|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.)|
|Match||When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)|
|ToString||Returns a string that represents the current object. (Inherited from Object.)|
|_Attribute.GetIDsOfNames||Maps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)|
|_Attribute.GetTypeInfo||Retrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)|
|_Attribute.GetTypeInfoCount||Retrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)|
|_Attribute.Invoke||Provides access to properties and methods exposed by an object. (Inherited from Attribute.)|
The 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 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 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 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.
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