Question

enter code here鉴于此例：

  Public Enum Gender
   Masculine
   Femenine
  End Enum

public class ViewModel

private _gender as Gender

    Public Property Gender() As Gender
      Get
        Return _gender 
      End Get
      Set(ByVal value As Gender)
        _gender = value
      End Set
    End Property

end class

 Private Sub Form_Load


 cmbGender.DataSource = [Enum].GetValues(GetType(Enums.Sexo)) //combobox shows gender ok
 cmbGender.DataBindings.Add(New Binding("SelectedItem",ViewModel , "Gender", False, DataSourceUpdateMode.OnPropertyChanged))

end sub

Combobox使用ViewModel getter在SelectedItem执行后立即设置Databindings.Add但在用户界面中SelectedItem更改时从不使用setter。

我做错了什么？

修改

感谢Sriram Sakthivel启发并检查组合框事件。最后的情况是：

当SelectedItem加注时，使用DataSourceUpdateMode.OnValidation，combobox.causesValidation = true和LostFocus有效。如果您需要onPropertyChanged，请使用SelectedIndex和下面的Sriram Sakthivel代码。

Answer 1

它会在LostFocus ComboBox事件中更新，因为SelectedItem不会提出更改通知（这是立即更新所必需的）。

作为一种变通方法，您可以使用SelectedIndex属性，该属性通过SelectedIndexChanged事件发布更改通知。但是有一个问题，SelectedIndex类型为Int32，您需要将其转换为Gender，反之亦然。

以下是您将如何做到这一点：C＃版

private void SetupBinding()
{
    var binding = new Binding("SelectedIndex", model, "Gender", true, DataSourceUpdateMode.OnPropertyChanged);
    binding.Format += binding_Format;
    binding.Parse += binding_Parse;
    comboBox1.DataBindings.Add(binding);
}

void binding_Parse(object sender, ConvertEventArgs e)
{
    if (e.DesiredType == typeof(Gender))
    {
        e.Value = comboBox1.Items[(int)e.Value];
    }
}

void binding_Format(object sender, ConvertEventArgs e)
{
    if (e.DesiredType == typeof(int))
    {
        e.Value = comboBox1.Items.IndexOf(e.Value);
    }
}

Vb.net很穷。所以我使用code converter将其从c＃转换为vb.net。

Private Sub SetupBinding()
    Dim binding = New Binding("SelectedIndex", model, "Gender", True, DataSourceUpdateMode.OnPropertyChanged)
    AddHandler binding.Format, AddressOf binding_Format
    AddHandler binding.Parse, AddressOf binding_Parse
    comboBox1.DataBindings.Add(binding)
End Sub

Private Sub binding_Parse(sender As Object, e As ConvertEventArgs)
    If e.DesiredType = GetType(Gender) Then
        e.Value = comboBox1.Items(CInt(e.Value))
    End If
End Sub

Private Sub binding_Format(sender As Object, e As ConvertEventArgs)
    If e.DesiredType = GetType(Integer) Then
        e.Value = comboBox1.Items.IndexOf(e.Value)
    End If
End Sub

在组合框中结合枚举

1 个答案: