ViewModel 通知绑定的 ComboBox List 已更改

Question

我有一个ComboBox 绑定到静态List。

我想更改列表中的项目，但组合框不会更新以反映更改。

---

XAML

<ComboBox x:Name="cbo" 
          ItemsSource="{Binding ComboBox_Items, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
          SelectedItem="{Binding cbo_SelectedItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
          HorizontalAlignment="Left"
          Margin="0,0,0,0" 
          VerticalAlignment="Top" 
          Width="100" />

---

C 夏普

ViewModel 类

获取/设置组合框项

public static List<string> _cbo_Items = new List<string>()
{
    "Item 1",
    "Item 2",
    "Item 3"
};

public static List<string> ComboBox_Items
{
    get { return _cbo_Items; }
    set { _cbo_Items = value;}
}

public static string cbo_SelectedItem { get; set; }

---

另一个类

用新项目更新列表

ViewModel._cbo_Items = new List<string>()
{
    "Item 4",
    "Item 5",
    "Item 6"
};

---

解决方案

我试过了，它在viewModel.OnPropertyChanged("ComboBox_Items") 上崩溃并出现空异常

public static ViewModel viewModel;

public event PropertyChangedEventHandler PropertyChanged;

private void OnPropertyChanged(string propertyName)
{
    if (PropertyChanged != null)
    {
        PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
}


public static List<string> ComboBox_Items
{
    get { return _cbo_Items; }
    set { _cbo_Items = value;
          viewModel.OnPropertyChanged("ComboBox_Items");
    }
}

Answer 1

当您“新建”列表时绑定被破坏，您可以使用 observablecollection 并清除然后添加项目而不是创建新实例。

还修复了组合框的 selecteditem 属性的绑定

<ComboBox x:Name="cbo" 
      ItemsSource="{Binding ComboBox_Items}"
      SelectedItem="{Binding cbo_SelectedItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
      HorizontalAlignment="Left"
      Margin="0,0,0,0" 
      VerticalAlignment="Top" 
      Width="100" />

而且最好删除 ComboBox_Items 的设置器以防止它被重新创建。