MVP、WinForms - 如何避免臃肿的视图、演示者和演示模型

Question

在 winforms 中实现 MVP 模式时，我经常发现具有太多属性、setter 和 getter 的臃肿视图接口。一个简单的例子是一个带有 3 个按钮和 7 个文本框的视图，所有这些都具有从视图中公开的值、启用和可见属性。为此添加验证结果，您可以轻松地得到一个具有 40 多个属性的界面。使用 Presentation Model，也会有一个具有相同数量属性的模型。

如何轻松地同步视图和表示模型，而不需要来回传递所有值的臃肿的表示器逻辑？ （使用 80 行演示者代码，想象一下模拟模型和视图的演示者测试看起来像..160 行代码只是为了模拟传输。）是否有任何框架可以在不诉诸 winforms 数据绑定的情况下处理这个问题？ （您可能想要使用与 winforms 视图不同的视图。根据某些人的说法，这种同步应该是演示者的工作。）您会使用 AutoMapper 吗？

也许我问错了问题，但在我看来，如果没有一些好的解决方案，MVP 很容易变得臃肿..

Answer 1

这只是一个想法，我知道有些人可能不喜欢它——你可以在这里做很多不同的事情。

如果您发现自己使用了大量样板代码，请将其封装。

public class UiField<ContentType>
{
    public bool IsEnabled { get; set; }
    public ContentType Value { get; set; }
    public bool IsVisible { get; set; }
}

在你看来，那么：

public interface ISampleView
{
    UiField<bool> IsStaffFullTime { get; set; }
    UiField<string> StaffName { get; set; }
    UiField<string> JobTitle { get; set; }
    UiField<int> StaffAge { get; set; }
    UiField<IList<string>> Certifications { get; set; }
}

在这里您总结了与每个字段相关的各种属性。

顺便说一句，我建议您不要手动存根这些接口进行测试——使用模拟框架。

Answer 2

我开始构建 Jay 的解决方案，然后意识到我正在构建的是适配器设计模式的实现。这是我最终得到的结果，它是 VB.Net 而不是 C#：

定义您只想设置一次的属性的适配器接口：

Public Interface IWinformsControlAdapter(Of T)

''' <summary>
''' Default value for the UI Control
''' </summary>
''' <returns></returns>
Property Value As T
Property IsEnabled As Boolean
Sub SetError(myValue As String)

''' <summary>
''' Select all the text in the UI Field if possible
''' </summary>
Sub [Select]()

''' <summary>
''' Gets a boolean value indicating whether all required inputs have been entered into the UI field
''' </summary>
''' <returns>true if all required input has been entered in the field</returns>
ReadOnly Property Completed As Boolean

Property DataSource As Object
Property DisplayMember As String
Property ValueMember As String
Property SelectedValue As Object
Property Checked As Boolean
End Interface

接口实现：

Public Class WinformsControlAdapter(Of T)
    Implements IWinformsControlAdapter(Of T)

    Private ReadOnly _control As Control 'The Adaptee
    Private ReadOnly _errorProvider As ErrorProvider
    Public Sub New(ByRef control As Control, ByRef errorProvider As ErrorProvider)
        _control = control
        _errorProvider = errorProvider
    End Sub

    Public Property Value As T Implements IWinformsControlAdapter(Of T).Value
        Get

            Select Case True
                Case TypeOf _control Is TextBoxBase 
                    'Typically for Textbox T = String, but not always: _control could be adapting to Integer for inputting numbers or MaskedTextbox could be adapting to Date for inputting dates, etc 
                    Return ConvertTo(Of T)(_control.Text)

                Case TypeOf _control Is RadioButton 
                    Dim myRadioButton As RadioButton = _control
                    Return ConvertTo(Of T)(myRadioButton.Checked)

                Case Else
                    Throw New NotImplementedException("Some other control.property needs to be added for .Value Property Get")

            End Select

        End Get
        Set(myValue As T)

            Select Case True
                Case TypeOf _control Is TextBoxBase 
                    _control.Text = ConvertTo(Of String)(myValue)

                Case TypeOf _control Is ListControl 
                    'Its debatable should it be the list or the selected value
                    DataSource = myValue  
                    'Dim myListControl As ListControl = _control
                    'myListControl.DataSource = ConvertTo(Of T)(myValue)

                Case TypeOf _control Is RadioButton 
                    Dim myRadioButton As RadioButton = _control
                    myRadioButton.Checked = ConvertTo(Of Boolean)(myValue)

                Case Else
                    Throw New NotImplementedException("Some other control.property needs to be added for .Value Property Set")
            End Select

        End Set
    End Property

    Public Property Checked As Boolean Implements IWinformsControlAdapter(Of T).Checked
        Get
            If TypeOf _control IsNot RadioButton Then Throw New NotImplementedException()

            Dim myRadioButton As RadioButton = _control
            Return myRadioButton.Checked
        End Get
        Set(myValue As Boolean)
            If TypeOf _control IsNot RadioButton Then Throw New NotImplementedException()

            Dim myRadioButton As RadioButton = _control
            myRadioButton.Checked = myValue
        End Set
    End Property

    Public ReadOnly Property Completed As Boolean Implements IWinformsControlAdapter(Of T).Completed
        Get
            If TypeOf _control IsNot MaskedTextBox Then Throw New NotImplementedException()

            Dim myMaskedTextBox As MaskedTextBox = _control
            Return myMaskedTextBox.MaskCompleted
        End Get
    End Property

    Public Property DataSource As Object Implements IWinformsControlAdapter(Of T).DataSource
        Get
            If TypeOf _control IsNot ListControl Then Throw New NotImplementedException()

            Dim myListControl As ListControl = _control
            Return myListControl.DataSource
        End Get
        Set(myValue As Object)
            If TypeOf _control IsNot ListControl Then Throw New NotImplementedException()

            Dim myListControl As ListControl = _control
            myListControl.DataSource = myValue
        End Set
    End Property

    Public Property DisplayMember As String Implements IWinformsControlAdapter(Of T).DisplayMember
        Get
            If TypeOf _control IsNot ListControl Then Throw New NotImplementedException()

                Dim myListControl As ListControl = _control
                Return myListControl.DisplayMember
        End Get
        Set(myValue As String)
            If TypeOf _control IsNot ListControl Then Throw New NotImplementedException()

            Dim myListControl As ListControl = _control
            myListControl.DisplayMember = myValue
        End Set
    End Property
    Public Property ValueMember As String Implements IWinformsControlAdapter(Of T).ValueMember
        Get
            If TypeOf _control IsNot ListControl Then Throw New NotImplementedException()

            Dim myListControl As ListControl = _control
            Return myListControl.ValueMember
        End Get
        Set(myValue As String)
            If TypeOf _control IsNot ListControl Then Throw New NotImplementedException()

            Dim myListControl As ListControl = _control
            myListControl.ValueMember = myValue
        End Set
    End Property
    Public Property SelectedValue As Object Implements IWinformsControlAdapter(Of T).SelectedValue
        Get
            If TypeOf _control IsNot ListControl Then Throw New NotImplementedException()

            Dim myListControl As ListControl = _control
            Return myListControl.SelectedValue
        End Get
        Set(myValue As Object)
            If TypeOf _control IsNot ListControl Then Throw New NotImplementedException()

            Dim myListControl As ListControl = _control
            myListControl.SelectedValue = myValue
        End Set
    End Property
    Public Function ConvertTo(Of T)(myValue As Object) As T
        If (TypeOf myValue Is T) Then
            Dim variable As T = myValue
            Return variable
        End If

        Try
            'Handling Nullable types i.e, int?, double?, bool? .. etc
            If Nullable.GetUnderlyingType(GetType(T)) <> Nothing Then
                Return TypeDescriptor.GetConverter(GetType(T)).ConvertFrom(myValue)
            End If

            Return Convert.ChangeType(myValue, GetType(T))

        Catch ex As Exception
            Return CType(Nothing, T) 'Return the default value for the type - same as C#: return default(T)
        End Try
    End Function
    Public Property IsEnabled As Boolean Implements IWinformsControlAdapter(Of T).IsEnabled
        Get
            Return _control.Enabled
        End Get
        Set(myValue As Boolean)
            _control.Enabled = myValue
        End Set
    End Property    

    ''' <summary>
    ''' Sets the error description string for the UI Field.
    ''' </summary>
    ''' <param name="myValue">The error message to assign to the control</param>
    Friend Sub SetError(myValue As String) Implements IWinformsControlAdapter(Of T).SetError
        _errorProvider.SetError(_control, myValue)
    End Sub

    Sub [Select]() Implements IWinformsControlAdapter(Of T).Select
        If TypeOf _control Is TextBoxBase Then
            Dim myTextBoxBase As TextBoxBase = _control
            myTextBoxBase.Select(0, _control.Text.Length)
        End If
    End Sub

End Class

在 WinForm/View 中，声明将使用适配器将视图控件公开为简单数据类型的属性：

Property YesNo1 As IWinformsControlAdapter(Of Boolean) Implements IMyView.YesNo1
Property YesNo2 As IWinformsControlAdapter(Of Boolean) Implements IMyView.YesNo2 
Property StartDate As IWinformsControlAdapter(Of Date?) Implements IMyView.StartDate
Property EndDate As IWinformsControlAdapter(Of Date?) Implements IMyView.EndDate

在 WinForm/View 构造函数中，将属性连接到 Winforms UI 控件（我也在使用 ErrorProvider）：

公共订阅 New() MyBase.New()

Try
    InitializeComponent()

    Yes = New WinformsControlAdapter(Of Boolean)(rdoHNSYes, ErrorProvider1)
    No = New WinformsControlAdapter(Of Boolean)(rdoHNSNo, ErrorProvider1)
    StartDate = New WinformsControlAdapter(Of Date?)(mskStartDate, ErrorProvider1)
    EndDate = New WinformsControlAdapter(Of Date?)(mskEndDate, ErrorProvider1)

在演示者中： Private ReadOnly _view As IMyView

Public Sub New(view As IMyView)
    _view = view 'Inject dependency
End Sub

现在在您的演示者代码中，您可以使用适配器属性：

_view.YesNo1.Value = True 
If _view.StartDate.Completed Then
etc
etc