Question

我有一个对象，其属性也是对象并绑定到文本框。我希望能够设置MyOriginalObj = MyNewOject并让文本框显示新值。这不起作用。我要做的是MyOriginalObj.PropertyA = MyNewObj.PropertyA。这将导致文本框更新。

我想避免使用后一种方法，因为我的实际类比下面的测试类有更多属性，并且会增加执行所有更新所需的代码。如果我必须，我想我可以解除绑定并绑定到新对象，但再次添加更多代码。 MyOriginalObj = MyNewObj方法将是最简单的解决方案，但我不确定它是否可行。请指教。

Dim fam As New Family

Public Class Person

    Dim _Age As Integer = 0
    Dim _Name As String = ""

    Public Property Age() As Integer
        Get
            Return _Age
        End Get
        Set(ByVal value As Integer)
            _Age = value
        End Set
    End Property

    Public Property Name() As String
        Get
            Return _Name
        End Get
        Set(ByVal value As String)
            _Name = value
        End Set
    End Property

    Public Sub New(ByVal age As Integer, ByVal name As String)

        With Me
            ._Age = age
            ._Name = name
        End With

    End Sub

End Class

-

Public Class Family

    Implements System.ComponentModel.INotifyPropertyChanged
    Public Event PropertyChanged(ByVal sender As Object, 
          ByVal e As System.ComponentModel.PropertyChangedEventArgs) _
          Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged

    Dim _Father As New Person(0, "")
    Dim _Mother As New Person(0, "")

    Public Property Father() As Person
        Get
            Return _Father
        End Get
        Set(ByVal value As Person)
            _Father = value
            RaiseEvent PropertyChanged(Me, 
                New System.ComponentModel.PropertyChangedEventArgs("Father"))
        End Set
    End Property

    Public Property Mother() As Person
        Get
            Return _Mother
        End Get
        Set(ByVal value As Person)
            _Mother = value
            RaiseEvent PropertyChanged(Me, 
                New System.ComponentModel.PropertyChangedEventArgs("Mother"))
        End Set
    End Property

End Class

-

Private Sub Form1_Load(ByVal sender As System.Object, 
                       ByVal e As System.EventArgs) Handles MyBase.Load

    TextBox1.DataBindings.Add("Text", fam, "Father.Name")
    TextBox2.DataBindings.Add("Text", fam, "Mother.Name")

End Sub

-

Private Sub Button1_Click(ByVal sender As System.Object, 
                          ByVal e As System.EventArgs) Handles Button1.Click

    ' Method A - works, textboxes displays the new values.
    ' fam.Father = New Person(30, "Joe")
    ' fam.Mother = New Person(29, "Jane")
    ' Exit Sub

    ' Method B - does not update textboxes.
    Dim fam2 As New Family
    fam2.Father = New Person(40, "Bob")
    fam2.Mother = New Person(39, "Betty")

    ' I would like the updated properties to be shown in the bound 
    ' textboxes when I set fam = fam2.  Object fam will contain 
    ' the new values but the textboxes will not reflect that.
    fam = fam2
    Console.WriteLine("{0},{1} : {2}, {3}", _
                      fam.Father.Name,  _
                      fam.Father.Age,  _
                      fam.Mother.Name,  _
                      fam.Mother.Age)

End Sub

Answer 1

您可以在family类中实现一个可以实现您所需要的方法。

Public Class Family

  . . .

  Public Sub ReplaceFamily(newFamily As Family)
    With newFamily
      Me.Father = .Father
      Me.Mother = .Mother
    End With
  End Sub

End Class

您的电话将如下所示：

fam.ReplaceFamily(fam2)

如果family中有很多属性，则可以在ReplaceFamily方法中使用反射，而不是单独设置每个属性。

如何通过设置ObjectA = ObjectB将绑定控件更新为对象

1 个答案: