Question

我遇到了ShouldSerialize功能的问题我在其上定义了一个带有标签（名为Label1）的usercontrol 现在我将下面的代码放在usercontrol类中：

NSString *searchString = @"EVBAR02";
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"imageUrl CONTAINS[cd] %@", searchString];

现在以新的形式包含usercontrol 在usercontrol的属性网格中，您可以找到TBValueRange属性如果右键单击属性名称，则可以重新启动该属性重新启动后，您可以在物业中看到值200 现在，重新生成项目会将属性重置为初始值（id 100）为什么价值200没有留下来？
如果我替换函数ShouldSerializeTBValueRange（）中的行NSPredicate *predicate = [NSPredicate predicateWithFormat:@"imageUrl CONTAINS[cd] 'EVBAR02'"];

不返回_Range.Equals（200）

它会起作用。我不明白。

任何人都可以解释一下吗？

Answer 1

这些方法按编码方式工作。似乎不按预期工作的事情是Not _Range.Equals(200)部分。

您将_Range初始化为100：Dim _Range As UShort = 100
然后，当{em>不 ShouldSerializeTBValueRange时，您的200方法告诉VS 保存范围值：{{1 }}

因此，当您在IDE中将其重置为Return _Range <> 200时，它不会保存200的值，并显示200的初始值。

代码使用一个值作为默认值100，但为100 test使用不同的值。您应该将其更改为使用默认值200：

ShouldSerialize

或更改Dim _Range As UShort = 200测试以使用ShouldSerialize：

100

将默认值视为默认值，并且仅使用一个值作为默认值，只使用Public Function ShouldSerializeTBValueRange() As Boolean Return _Range <> 100 End Function和ShouldSerializexxx按预期工作，而不需要任何其他内容。

Resetxxx

使用一个值作为实际默认值（100），然后根据不同值（200）返回T / F会导致

在不需要时保存100

200 不应保存

' THIS is the default value - ' ie the value that need not be saved because the ' control automatically starts with that value Dim _Range As UShort = 200US ' Controls: ' - displays the prop value in Bold in the property window ' when the value is NOT the default ' - saves the value when it is NOT the default ' - enables/disables the RESET function Public Function ShouldSerializeTBValueRange() As Boolean Return (_Range <> 200US) End Function菜单项和粗体值处于错误状态

奇怪的是Reset似乎失败了。它在重置（返回200）后返回Not _Range.Equals(200)，这会导致值在真正不应该保存时保存。这有两个重载：

False

如果您传递的不是实际的UInt16.Equals(obj As Object) As Boolean UInt16.Equals(v As UShort) As Boolean，则该值将被设置为UInt16/UShort。因此，Object正在使用第一个，因为Not _Range.Equals(200)是200。该版本的ILCode是：

Int32

测试将无法通过第一次测试，因为public override bool Equals(object obj) { return obj is ushort && this == (ushort)obj; }包含obj。如果您传递Int32，它将起作用：

UShort

理解不同数据类型的所有充分理由，避免装箱（UShort.Equals(_Range, 200US) 'or: _Range.Equals(200US)）并永远设置As Object。

Answer 2

谢谢大家花时间在我的问题上我找到了答案：当ShouldSerialize函数返回false时，属性值不会保存在文件Form1.designer.vb中，因此它获取原始值。
对于我需要的，ShouldSerialize函数应该总是返回true。

Public Function ShouldSerializeTBValueRange() As Boolean
    Return true
End Function

因此将始终保存属性值现在，我正在寻找的是如何控制属性网格的上下文菜单我想要选择＆＃34; Reinit＆＃34;当价值好的时候会变灰。

Answer 3

最后，我发现了一些东西，使用了PropertyDescriptor。对于谁感兴趣，我们可以在designer.vb文件中保存属性并测试要重置的值这是我的程序，基于MSDN - Microsft的文章：

Imports System.ComponentModel
Imports System.Windows.Forms.Design

<Designer(GetType(DemoControlDesigner))>
Public Class UserControl1

Dim _MyProperty1 As String = "Test1"
Dim _MyProperty2 As Integer = 100
Dim _MyProperty3 As UShort = 200

Public Sub New()
    InitializeComponent()
End Sub

Public Function CanResetMyProperty1() As Boolean
    Return _MyProperty1 <> "Test"
End Function

Public Sub ResetMyProperty1()
    _MyProperty1 = "Test"
End Sub

Public Property MyProperty1 As String
    Get
        Return _MyProperty1
    End Get
    Set(ByVal Value As String)
        _MyProperty1 = Value
    End Set
End Property

Public Function CanResetMyProperty2() As Boolean
    Return _MyProperty2 <> 150
End Function

Public Sub ResetMyProperty2()
    _MyProperty2 = 150
End Sub

Public Property MyProperty2 As Integer
    Get
        Return _MyProperty2
    End Get
    Set(ByVal Value As Integer)
        _MyProperty2 = Value
    End Set
End Property

Public Function CanResetMyProperty3() As Boolean
    Return _MyProperty3 <> _MyProperty2
End Function

Public Sub ResetMyProperty3()
    _MyProperty3 = _MyProperty2
End Sub

Public Property MyProperty3 As UShort
    Get
        Return _MyProperty3
    End Get
    Set(ByVal Value As UShort)
        _MyProperty3 = Value
    End Set
End Property

End Class


Friend NotInheritable Class SerializePropertyDescriptor
Inherits PropertyDescriptor
Private _pd As PropertyDescriptor = Nothing

Public Sub New(ByVal pd As PropertyDescriptor)
    MyBase.New(pd)
    _pd = pd
End Sub

Public Overrides ReadOnly Property Attributes() As AttributeCollection
    Get
        Return Me._pd.Attributes
    End Get
End Property

Protected Overrides Sub FillAttributes(ByVal attributeList As IList)
    MyBase.FillAttributes(attributeList)
End Sub

Public Overrides ReadOnly Property ComponentType() As Type
    Get
        Return Me._pd.ComponentType
    End Get
End Property

Public Overrides ReadOnly Property Converter() As TypeConverter
    Get
        Return Me._pd.Converter
    End Get
End Property

Public Overrides Function GetEditor(ByVal editorBaseType As Type) As Object
    Return Me._pd.GetEditor(editorBaseType)
End Function

Public Overrides ReadOnly Property IsReadOnly() As Boolean
    Get
        Return Me._pd.IsReadOnly
    End Get
End Property

Public Overrides ReadOnly Property PropertyType() As Type
    Get
        Return Me._pd.PropertyType
    End Get
End Property

Public Overrides Function CanResetValue(ByVal component As Object) As Boolean
    Try
        Return CallByName(component, "CanReset" & _pd.Name, CallType.Get, Nothing)
    Catch ex As Exception
        MsgBox(ex.Message)
    End Try
    Return False
End Function

Public Overrides Function GetValue(ByVal component As Object) As Object
    Return Me._pd.GetValue(component)
End Function

Public Overrides Sub ResetValue(ByVal component As Object)
    Me._pd.ResetValue(component)
End Sub

Public Overrides Sub SetValue(ByVal component As Object, ByVal val As Object)
    Me._pd.SetValue(component, val)
End Sub

Public Overrides Function ShouldSerializeValue(ByVal component As Object) As Boolean
    Return True
End Function

End Class

Class DemoControlDesigner
Inherits ControlDesigner
Dim PropertiesToSerialize As String() = {"MyProperty1", "MyProperty2", "MyProperty3"}

Protected Overrides Sub PostFilterProperties(ByVal properties As IDictionary)
    Dim original As PropertyDescriptor
    For Each PropName As String In PropertiesToSerialize
        If properties.Contains(PropName) Then
            original = properties(PropName)
            properties(PropName) = New SerializePropertyDescriptor(original)
        End If
    Next
    MyBase.PostFilterProperties(properties)
End Sub
End Class

对于应该序列化并测试重置的每个属性，我们应该编写一个子“CanResetPropertyName”来测试要重置的值（参见示例）。
即使我们重新启动项目，价值仍然存在它对我来说很好，也许它可以改进。

问候。

VB .Net - ShouldSerialize函数

3 个答案: