ASP.NET MVC Json ModelBinder

Imports System
Imports System.IO
Imports System.Linq
Imports System.Collections.Generic
Imports System.Web.Helpers
Imports System.Web.Mvc

Public Class DynamicJsonAttribute
   Inherits CustomModelBinderAttribute

   Public Property MatchName As Boolean

   Public Overrides Function GetBinder() As System.Web.Mvc.IModelBinder
      Return New DynamicJsonBinder(MatchName)
   End Function

End Class

Public Class DynamicJsonBinder
   Implements IModelBinder

   Private ReadOnly matchName As Boolean

   Sub New(matchName)
      Me.matchName = matchName
   End Sub

   Public Function BindModel(controllerContext As System.Web.Mvc.ControllerContext, bindingContext As System.Web.Mvc.ModelBindingContext) As Object Implements System.Web.Mvc.IModelBinder.BindModel
      Dim contentType = controllerContext.HttpContext.Request.ContentType
      If Not contentType.StartsWith("application/json", StringComparison.OrdinalIgnoreCase) Then
         Return Nothing
      End If
      Dim bodyText As String
      Using myStream As IO.Stream = controllerContext.HttpContext.Request.InputStream
         myStream.Seek(0, SeekOrigin.Begin)
         Using myReader As New StreamReader(myStream)
            bodyText = myReader.ReadToEnd()
         End Using
      End Using

      If (String.IsNullOrEmpty(bodyText)) Then
         Return Nothing
      End If

      Dim parsed = Json.Decode(bodyText)
      If Not matchName Then
         Return parsed
      End If
      Dim members As IEnumerable(Of String) = parsed.GetDynamigMemberNames()
      If members Is Nothing OrElse members.Contains(bindingContext.ModelName) Then
         Return parsed(bindingContext.ModelName)
      End If
      Return Nothing
   End Function

End Class