GetType 上的 InvalidOperationException

Question

我尝试使用 XMLSerializer 在 VB 中序列化一个 Class。但是当我为我的 Class 调用 GetType 时，我得到了一个 InvalidOperationException 错误。

Dim Playlist_serialize As New XmlSerializer(p.GetType)

这是我的 class :

Public Class Playlist
Private p_name As String
Private p_elements As List(Of Playlist_element)

Sub New()
    p_elements = New List(Of Playlist_element)
End Sub

Public Property Name() As String
    Get
        Name = p_name
    End Get
    Set(value As String)
        p_name = value
    End Set
End Property

Public Property Elements() As List(Of Playlist_element)
    Get
        Elements = p_elements
    End Get
    Set(value As List(Of Playlist_element))
        p_elements = value
    End Set
End Property

这是我的 Playlist_element :

Public Class Playlist_element
Private p_Name As String
Private p_Type As String
Private p_Genre As String

Public Property Name() As String
    Get
        Name = p_Name
    End Get
    Set(value As String)
        p_Name = value
    End Set
End Property

Public Property Type() As String
    Get
        Type = p_Type
    End Get
    Set(value As String)
        p_Type = value
    End Set
End Property

Public Property Genre() As String
    Get
        Genre = p_Genre
    End Get
    Set(value As String)
        p_Genre = value
    End Set
End Property

Sub New(ByVal name As String, ByVal type As String, ByVal genre As String)
    Me.Name = name
    Me.Genre = genre
    Me.Type = Type
End Sub
End Class

Answer 1

Playlist_element 的编码方式存在几个问题。首先，您的属性吸气剂是错误的。他们需要 return 支持字段：

Public Property Name() As String
    Get
        ' this does nothing:
        'Name = p_Name
        Return p_Name
    End Get
    Set(value As String)
        p_Name = value
    End Set
End Property

接下来，即使可以，我也不会使用 Type 作为属性名称。如果深入内部异常并查看消息，它会告诉您它无法序列化 PlayList_element，因为它没有简单的构造函数。所有序列化程序都需要这个，因为他们不知道如何使用：

Sub New(ByVal name As String, ByVal type As String, ByVal genre As String)
    p_Name = name
    p_Genre = genre
    p_Type = type
End Sub

' add:
Public Sub New()

End Sub

它应该可以正常工作。我应该注意，从 VS2010 开始，您可以使用自动实现的属性并跳过很多该代码：

Public Class Element

    Public Property Name() As String
    Public Property Type() As String
    Public Property Genre() As String

    Sub New(name As String, type As String, genre As String)
        _Name = name
        _Genre = genre
        _Type = type
    End Sub

    Public Sub New()

    End Sub
End Class

VS 提供 "hidden" 支持字段，与 _Name、_Genre 等

GetType 上的 InvalidOperationException

InvalidOperationException on GetType

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