检索列表中的项目

Question

我有一个添加OrderItem的购物车。在OrderItem中，我有一个（产品和服务作为类）

我的问题：当我添加产品和服务时，我正在努力检索ListCollection中的项目。

我正在建立一个包含产品和服务目录的网站。我的目标是实现一个存储订单商品的购物车。

我有以下课程：

1. OrderItem将是Product和Service类的父类
2. Product：待售产品
3. Service：待售服务
4. CartItem：此课程将区分产品和服务
5. ShoppingCart：将添加OrderItem

我的代码如下。

Public MustInherit Class OrderItem
    Private m_enuItemType As TypeOfItem = TypeOfItem.None
    Private m_strUserID As String = ""

    Public Sub New(ByVal enuItemType As TypeOfItem)
        m_enuItemType = enuItemType
    End Sub
    Public Enum TypeOfItem
        None = 0
        Product = 1
        Service = 2
    End Enum
    Public Property ItemType() As TypeOfItem
        Get
            Return m_enuItemType
        End Get
        Set(ByVal value As TypeOfItem)
            m_enuItemType = value
        End Set
    End Property
    Public Property UserID() As String
        Get
            Return m_strUserID
        End Get
        Set(ByVal value As String)
            m_strUserID = value
        End Set
    End Property
End Class

---

Public Class Service
    Inherits OrderItem

    'service Booking Business object 
    Private objServiceBooking As Bo_Dall_Layer.ServiceBooking

    Public Sub New(ByVal enuItemType As TypeOfItem)
        MyBase.New(enuItemType)
    End Sub

    Public Property CartService() As Bo_Dall_Layer.ServiceBooking
        Get
            Return objServiceBooking
        End Get
        Set(ByVal value As Bo_Dall_Layer.ServiceBooking)
            objServiceBooking = value
        End Set
    End Property

End Class

---

Public Class Product
    Inherits OrderItem
    'product Business object
    Private objProduct As Bo_Dall_Layer.BoProduct

    Public Sub New(ByVal enuItemType As TypeOfItem)
        MyBase.New(enuItemType)
    End Sub

    Public Property Boprd() As Bo_Dall_Layer.BoProduct
        Get
            Return objProduct
        End Get
        Set(ByVal value As Bo_Dall_Layer.BoProduct)
            objProduct = value
        End Set
    End Property


End Class

---

Public Class CartItem


    Private m_enuItemType As ItemType
    Private m_objOrderItem As OrderItem

    Private Enum ItemType
        Product = 1
        Service = 2
    End Enum

    Public Property Item(ByVal objItem As OrderItem) As OrderItem
        Get
            Return m_objOrderItem
        End Get
        Set(ByVal value As OrderItem)
            m_objOrderItem = value
        End Set
    End Property

End Class

---

Public Class UserShoppingCart

    Private m_objArrListOfItems As List(Of OrderItem)

    Public Sub New()
        m_objArrListOfItems = New List(Of OrderItem)(10)
    End Sub

    Public Function AddItem(ByVal objOrderItem As OrderItem) As Boolean
        Try
            ' Validate item to check if it is already in the list
            ' If yes, increment counter, otherwise add new item to the list

            m_objArrListOfItems.Add(objOrderItem)

        Catch ex As Exception
            ' Log error
        End Try
    End Function

    Public ReadOnly Property ListOfItems() As List(Of OrderItem)
        Get
            Return m_objArrListOfItems
        End Get
    End Property

End Class

//检索orderitem以进行显示

        Dim arr As New ArrayList
        Dim arrService As New ArrayList

        Dim objlist As CartProduct
        Dim objServiceList As CartService



        For Each OrderItem As CartProduct In g_objUserShoppingCart.ListOfItems
            objlist = New CartProduct(Global.OrderItem.TypeOfItem.Product)
            objlist.ProductId = OrderItem.ProductId
            arr.Add(objlist)
        Next

        ''---------------------------------------------------


        For Each OrderItem As CartService In g_objUserShoppingCart.ListOfItems
            objServiceList = New CartService(Global.OrderItem.TypeOfItem.Service)
            objServiceList.ServiceName = OrderItem.ServiceName
            arrService.Add(objServiceList)
        Next


        If Not IsPostBack Then
            ProductCartView.DataSource = arr
            ProductCartView.DataBind()
            ServiceCartView.DataSource = arrService
            ServiceCartView.DataBind()
        End If

//错误无法转换CartService对象我该如何实现呢，谢谢你

Public Class CartService 
    Inherits OrderItem 
    Private m_serviceName As String = "" 
    Public Sub New(ByVal enuItemType As TypeOfItem) 
        MyBase.New(enuItemType) 
    End Sub 
    Public Property ServiceName() As String 
        Get Return m_serviceName End Get 
        Set(ByVal value As String) m_serviceName = value End Set 
    End Property 
End Class