gistfile1.bas

Imports System
Imports System.Web
Imports System.Web.Mvc
Imports System.IO
Imports System.Xml
Imports System.Text
Imports System.Collections.Generic
Imports System.Web.Script.Serialization
Imports System.Runtime.Serialization
Imports System.Reflection
Imports System.Reflection.Emit

Public Class restResult
    Inherits ActionFilterAttribute

    Private _actionParams As [String]()

    ''// for deserialization 
    Public Sub New(ByVal ParamArray parameters As [String]())
        Me._actionParams = parameters
    End Sub


    ''// SERIALIZE
    Public Overrides Sub OnActionExecuted(ByVal filterContext As ActionExecutedContext)
        If Not (TypeOf filterContext.Result Is ViewResult) Then
            Exit Sub
        End If

        ' // SETUP 
        Dim utf8 As New UTF8Encoding(False)
        Dim request As HttpRequestBase = filterContext.RequestContext.HttpContext.Request
        Dim contentType As [String] = If(request.ContentType, String.Empty)
        Dim view As ViewResult = DirectCast(filterContext.Result, ViewResult)
        Dim data = view.ViewData.Model


        ' JSON 
        If contentType.Contains("application/json") OrElse request.IsAjaxRequest() Then
            Using stream = New MemoryStream()
                Dim js As New JavaScriptSerializer()
                'Här kan det bli fel, tog bort key . c....
                Dim content As [String] = js.Serialize(data)
                filterContext.Result = New ContentResult() With { _
                 .ContentType = "application/json", _
                 .Content = content, _
                 .ContentEncoding = utf8 _
                }

            End Using
        ElseIf contentType.Contains("text/xml") Then
            ' MemoryStream to encapsulate as UTF-8 (default UTF-16) 
            ' http://stackoverflow.com/questions/427725/ 
            ' 
            ' MemoryStream also used for atomicity but not here 
            ' http://stackoverflow.com/questions/486843/ 
            Using stream As New MemoryStream(500)
                Using xmlWriter = XmlTextWriter.Create(stream, New XmlWriterSettings() With { _
                 .OmitXmlDeclaration = True, _
                 .Encoding = utf8, _
                 .Indent = True _
                })

                    ' knownTypes 
                    ' maxItemsInObjectGraph 
                    ' ignoreExtensionDataObject 
                    ' preserveObjectReference - overcomes cyclical reference issues 
                    ' dataContractSurrogate 
                    '   Dim x As New datacontractserializer
                    '   Dim x As datacontractSerializer = New datacontractserializer(
                    ' Dim ser As New DataContractSerializer(GetType(Person))
                    Dim ser As New DataContractSerializer(data.[GetType](), Nothing, 65536, False, True, Nothing)
                    ser.WriteObject(stream, data)
                End Using

                filterContext.Result = New ContentResult() With { _
                 .ContentType = "text/xml", _
                 .Content = utf8.GetString(stream.ToArray()), _
                 .ContentEncoding = utf8 _
                }
            End Using
        End If
    End Sub

    ' DESERIALIZE 
    Public Overrides Sub OnActionExecuting(ByVal filterContext As ActionExecutingContext)

        If _actionParams Is Nothing OrElse _actionParams.Length = 0 Then
            Exit Sub
        End If

        Dim request As HttpRequestBase = filterContext.RequestContext.HttpContext.Request
        Dim contentType As [String] = If(request.ContentType, String.Empty)
        Dim isJson As [Boolean] = contentType.Contains("application/json")


        If Not isJson Then
            Exit Sub
        End If
        '@@todo Deserialize POX 

        ' JavascriptSerialier expects a single type to deserialize 
        ' so if the response contains multiple disparate objects to deserialize 
        ' we dynamically build a new wrapper class with fields representing those 
        ' object types, deserialize and then unwrap 

        Dim paramDescriptors As ParameterDescriptor() = filterContext.ActionDescriptor.GetParameters()
        Dim complexType As [Boolean] = paramDescriptors.Length > 1

        Dim wrapperClass As Type
        If complexType Then
            Dim parameterInfo As New Dictionary(Of String, Type)
            For Each p As ParameterDescriptor In paramDescriptors
                parameterInfo.Add(p.ParameterName, p.ParameterType)
            Next
            wrapperClass = BuildWrapperClass(parameterInfo)
        Else
            wrapperClass = paramDescriptors(0).ParameterType
        End If

        Dim json As [String]
        Using sr = New StreamReader(request.InputStream)
            json = sr.ReadToEnd()
        End Using

        ' then deserialize json as instance of dynamically created wrapper class 
        Dim serializer As New JavaScriptSerializer()
        Dim result = GetType(JavaScriptSerializer).GetMethod("Deserialize").MakeGenericMethod(wrapperClass).Invoke(serializer, New Object() {json})

        ' then get fields from wrapper class assign the values back to the action params 
        If complexType Then
            For i As Int32 = 0 To paramDescriptors.Length - 1
                Dim pd As ParameterDescriptor = paramDescriptors(i)

                filterContext.ActionParameters(pd.ParameterName) = wrapperClass.GetField(pd.ParameterName).GetValue(result)
            Next
        Else
            Dim pd As ParameterDescriptor = paramDescriptors(0)
            filterContext.ActionParameters(pd.ParameterName) = result
        End If

    End Sub
    Private Function BuildWrapperClass(ByVal parameterInfo As Dictionary(Of String, Type)) As Type
        Dim assemblyName As New AssemblyName()
        assemblyName.Name = "DynamicAssembly"
        Dim appDomain__1 As AppDomain = AppDomain.CurrentDomain
        Dim assemblyBuilder As AssemblyBuilder = appDomain__1.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run)
        Dim moduleBuilder As ModuleBuilder = assemblyBuilder.DefineDynamicModule("DynamicModule")
        Dim typeBuilder As TypeBuilder = moduleBuilder.DefineType("DynamicClass", TypeAttributes.[Public] Or TypeAttributes.[Class])

        For Each entry As KeyValuePair(Of String, Type) In parameterInfo
            Dim paramName As [String] = entry.Key
            Dim paramType As Type = entry.Value
            Dim field As FieldBuilder = typeBuilder.DefineField(paramName, paramType, FieldAttributes.[Public])
        Next

        Dim generatedType As Type = typeBuilder.CreateType()
        ' object generatedObject = Activator.CreateInstance(generatedType); 

        Return generatedType
    End Function

End Class