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question: how can you keep things DRY by only applying metadata information for dataannotations and validation on the master class, and then reuse this on the viewmodels?

example:
class book (domain model) and the metadata

VB
Imports System.ComponentModel.DataAnnotations

<MetadataType(GetType(BookMetaData))>
Public Class Book
    Public Property BookID As Integer

    Public Property Title As String
    Public Property Author As String

    Public Property ISBN As String
End Class

Public Class BookMetaData
    <Key()>
    Public Property BookID As Integer

    <Display(name:="Book Title")>
    <StringLength(150)>
    Public Property Title As String
    <Display(name:="Author Name")>
    <StringLength(50)>
    Public Property Author As String

    Public Property ISBN As String
End Class


then trying to apply the same dataannotations to a viewmodel BookTitleViewModel with only some fields of the original class
VB
Imports System.ComponentModel.DataAnnotations
<MetadataType(GetType(BookMetaData))>
Public Class BookTitleViewModel
    Public Property BookID As Integer

    Public Property Title As String
End Class


this throws an error, because not all fields are present:
The associated metadata type for type 'MvcApplicationMetaData.BookTitleViewModel' contains the following unknown properties or fields: Author, ISBN. Please make sure that the names of these members match the names of the properties on the main type.


how can I apply the metadata for just the existing fields?
Posted

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