Тестовая среда PayPal ASP.NET

Question

Я пытался следовать этой статье, чтобы внедрить тестовую транзакцию PayPal в мое веб-приложение. https://docs.microsoft.com/en-us/aspnet/web-forms/overview/getting-started/getting-started-with-aspnet-45-web-forms/checkout-and-payment-with-paypal

Однако, когда я конвертирую код из C # в VB, вот что я получил:

Imports System
Imports System.Collections
Imports System.Collections.Specialized
Imports System.IO
Imports System.Net
Imports System.Text
Imports System.Data
Imports System.Configuration
Imports System.Web
Imports WingtipToys
Imports WingtipToys.Models
Imports System.Collections.Generic
Imports System.Linq

Public Class NVPAPICaller
    Private Const bSandbox As Boolean = True
    Private Const CVV2 As String = "CVV2"
    Private pEndPointURL As String = "https://api-3t.paypal.com/nvp"
    Private host As String = "www.paypal.com"
    Private pEndPointURL_SB As String = "https://api-3t.sandbox.paypal.com/nvp"
    Private host_SB As String = "www.sandbox.paypal.com"
    Private Const SIGNATURE As String = "SIGNATURE"
    Private Const PWD As String = "PWD"
    Private Const ACCT As String = "ACCT"
    Public APIUsername As String = "<Your API Username>"
    Private APIPassword As String = "<Your API Password>"
    Private APISignature As String = "<Your Signature>"
    Private Subject As String = ""
    Private BNCode As String = "PP-ECWizard"
    Private Const Timeout As Integer = 15000
    Private Shared ReadOnly SECURED_NVPS As String() = New String() {ACCT, CVV2, SIGNATURE, PWD}

    Public Sub SetCredentials(ByVal Userid As String, ByVal Pwd As String, ByVal Signature As String)
    APIUsername = Userid
    APIPassword = Pwd
    APISignature = Signature
End Sub

    Public Function ShortcutExpressCheckout(ByVal amt As String, ByRef token As String, ByRef retMsg As String) As Boolean
    If bSandbox Then
        pEndPointURL = pEndPointURL_SB
        host = host_SB
    End If

    Dim returnURL As String = "https://localhost:44300/Checkout/CheckoutReview.aspx"
    Dim cancelURL As String = "https://localhost:44300/Checkout/CheckoutCancel.aspx"
    Dim encoder As NVPCodec = New NVPCodec()
    encoder("METHOD") = "SetExpressCheckout"
    encoder("RETURNURL") = returnURL
    encoder("CANCELURL") = cancelURL
    encoder("BRANDNAME") = "Wingtip Toys Sample Application"
    encoder("PAYMENTREQUEST_0_AMT") = amt
    encoder("PAYMENTREQUEST_0_ITEMAMT") = amt
    encoder("PAYMENTREQUEST_0_PAYMENTACTION") = "Sale"
    encoder("PAYMENTREQUEST_0_CURRENCYCODE") = "USD"

    Using myCartOrders As WingtipToys.Logic.ShoppingCartActions = New WingtipToys.Logic.ShoppingCartActions()
        Dim myOrderList As List(Of CartItem) = myCartOrders.GetCartItems()

        For i As Integer = 0 To myOrderList.Count - 1
            encoder("L_PAYMENTREQUEST_0_NAME" & i) = myOrderList(i).Product.ProductName.ToString()
            encoder("L_PAYMENTREQUEST_0_AMT" & i) = myOrderList(i).Product.UnitPrice.ToString()
            encoder("L_PAYMENTREQUEST_0_QTY" & i) = myOrderList(i).Quantity.ToString()
        Next
    End Using

    Dim pStrrequestforNvp As String = encoder.Encode()
    Dim pStresponsenvp As String = HttpCall(pStrrequestforNvp)
    Dim decoder As NVPCodec = New NVPCodec()
    decoder.Decode(pStresponsenvp)
    Dim strAck As String = decoder("ACK").ToLower()

    If strAck IsNot Nothing AndAlso (strAck = "success" OrElse strAck = "successwithwarning") Then
        token = decoder("TOKEN")
        Dim ECURL As String = "https://" & host & "/cgi-bin/webscr?cmd=_express-checkout" & "&token=" & token
        retMsg = ECURL
        Return True
    Else
        retMsg = "ErrorCode=" & decoder("L_ERRORCODE0") & "&" & "Desc=" & decoder("L_SHORTMESSAGE0") & "&" & "Desc2=" & decoder("L_LONGMESSAGE0")
        Return False
    End If
End Function

Public Function GetCheckoutDetails(ByVal token As String, ByRef PayerID As String, ByRef decoder As NVPCodec, ByRef retMsg As String) As Boolean
    If bSandbox Then
        pEndPointURL = pEndPointURL_SB
    End If

    Dim encoder As NVPCodec = New NVPCodec()
    encoder("METHOD") = "GetExpressCheckoutDetails"
    encoder("TOKEN") = token
    Dim pStrrequestforNvp As String = encoder.Encode()
    Dim pStresponsenvp As String = HttpCall(pStrrequestforNvp)
    decoder = New NVPCodec()
    decoder.Decode(pStresponsenvp)
    Dim strAck As String = decoder("ACK").ToLower()

    If strAck IsNot Nothing AndAlso (strAck = "success" OrElse strAck = "successwithwarning") Then
        PayerID = decoder("PAYERID")
        Return True
    Else
        retMsg = "ErrorCode=" & decoder("L_ERRORCODE0") & "&" & "Desc=" & decoder("L_SHORTMESSAGE0") & "&" & "Desc2=" & decoder("L_LONGMESSAGE0")
        Return False
    End If
End Function

Public Function DoCheckoutPayment(ByVal finalPaymentAmount As String, ByVal token As String, ByVal PayerID As String, ByRef decoder As NVPCodec, ByRef retMsg As String) As Boolean
    If bSandbox Then
        pEndPointURL = pEndPointURL_SB
    End If

    Dim encoder As NVPCodec = New NVPCodec()
    encoder("METHOD") = "DoExpressCheckoutPayment"
    encoder("TOKEN") = token
    encoder("PAYERID") = PayerID
    encoder("PAYMENTREQUEST_0_AMT") = finalPaymentAmount
    encoder("PAYMENTREQUEST_0_CURRENCYCODE") = "USD"
    encoder("PAYMENTREQUEST_0_PAYMENTACTION") = "Sale"
    Dim pStrrequestforNvp As String = encoder.Encode()
    Dim pStresponsenvp As String = HttpCall(pStrrequestforNvp)
    decoder = New NVPCodec()
    decoder.Decode(pStresponsenvp)
    Dim strAck As String = decoder("ACK").ToLower()

    If strAck IsNot Nothing AndAlso (strAck = "success" OrElse strAck = "successwithwarning") Then
        Return True
    Else
        retMsg = "ErrorCode=" & decoder("L_ERRORCODE0") & "&" & "Desc=" & decoder("L_SHORTMESSAGE0") & "&" & "Desc2=" & decoder("L_LONGMESSAGE0")
        Return False
    End If
End Function

Public Function HttpCall(ByVal NvpRequest As String) As String
    Dim url As String = pEndPointURL
    Dim strPost As String = NvpRequest & "&" & buildCredentialsNVPString()
    strPost = strPost & "&BUTTONSOURCE=" & HttpUtility.UrlEncode(BNCode)
    Dim objRequest As HttpWebRequest = CType(WebRequest.Create(url), HttpWebRequest)
    objRequest.Timeout = Timeout
    objRequest.Method = "POST"
    objRequest.ContentLength = strPost.Length

    Try

        Using myWriter As StreamWriter = New StreamWriter(objRequest.GetRequestStream())
            myWriter.Write(strPost)
        End Using

    Catch __unusedException1__ As Exception
    End Try

    Dim objResponse As HttpWebResponse = CType(objRequest.GetResponse(), HttpWebResponse)
    Dim result As String

    Using sr As StreamReader = New StreamReader(objResponse.GetResponseStream())
        result = sr.ReadToEnd()
    End Using

    Return result
End Function

Private Function buildCredentialsNVPString() As String
    Dim codec As NVPCodec = New NVPCodec()
    If Not IsEmpty(APIUsername) Then codec("USER") = APIUsername
    If Not IsEmpty(APIPassword) Then codec(PWD) = APIPassword
    If Not IsEmpty(APISignature) Then codec(SIGNATURE) = APISignature
    If Not IsEmpty(Subject) Then codec("SUBJECT") = Subject
    codec("VERSION") = "88.0"
    Return codec.Encode()
End Function

Public Shared Function IsEmpty(ByVal s As String) As Boolean
    Return s Is Nothing OrElse s.Trim() = String.Empty
End Function
End Class

Public NotInheritable Class NVPCodec
Inherits NameValueCollection

Private Const AMPERSAND As String = "&"
Private Const EQUALS As String = "="
Private Shared ReadOnly AMPERSAND_CHAR_ARRAY As Char() = AMPERSAND.ToCharArray()
Private Shared ReadOnly EQUALS_CHAR_ARRAY As Char() = EQUALS.ToCharArray()

Public Function Encode() As String
    Dim sb As StringBuilder = New StringBuilder()
    Dim firstPair As Boolean = True

    For Each kv As String In AllKeys
        Dim name As String = HttpUtility.UrlEncode(kv)
        Dim value As String = HttpUtility.UrlEncode(Me(kv))

        If Not firstPair Then
            sb.Append(AMPERSAND)
        End If

        sb.Append(name).Append(EQUALS).Append(value)
        firstPair = False
    Next

    Return sb.ToString()
End Function

Public Sub Decode(ByVal nvpstring As String)
    Clear()

    For Each nvp As String In nvpstring.Split(AMPERSAND_CHAR_ARRAY)
        Dim tokens As String() = nvp.Split(EQUALS_CHAR_ARRAY)

        If tokens.Length >= 2 Then
            Dim name As String = HttpUtility.UrlDecode(tokens(0))
            Dim value As String = HttpUtility.UrlDecode(tokens(1))
            Add(name, value)
        End If
    Next
End Sub

Public Sub Add(ByVal name As String, ByVal value As String, ByVal index As Integer)
    Me.Add(GetArrayName(index, name), value)
End Sub

Public Sub Remove(ByVal arrayName As String, ByVal index As Integer)
    Me.Remove(GetArrayName(index, arrayName))
End Sub

Default Public Property Item(ByVal name As String, ByVal index As Integer) As String
    Get
        Return Me(GetArrayName(index, name))
    End Get
    Set(ByVal value As String)
        Me(GetArrayName(index, name)) = value
    End Set
End Property

Private Shared Function GetArrayName(ByVal index As Integer, ByVal name As String) As String
    If index < 0 Then
        Throw New ArgumentOutOfRangeException("index", "index cannot be negative : " & index)
    End If

    Return name & index
End Function
End Class

И после вставки вышеуказанного VB-кода в visual studio я получил ошибки в переменных «encoder» и «decoder».

Может кто-нибудь подсказать мне, как внедрить PayPal Sandbox с помощью ASP.NET WebForms VB.NET?