Question

我想使用ReactiveUI将我的viewmodel中的属性绑定到Windows窗体应用程序中的ComboBox。

我在WPF中找到了几个示例，但没有使用Windows窗体的示例。

编辑：第1部分：将所选值绑定到以下评论示例：

this.Bind(ViewModel, vm => vm.ViewModelProperty, v => v.comboBox.SelectedValue, comboBox.Events().SelectedValueChanged);

我收到错误：CS1955 Non-invocable member 'Component.Events' cannot be used like a method.

第2部分：将ComboBox中的项目绑定到viewmodel中的集合？不知道怎么做

Answer 1

首先，您的视图应该实现IViewFor<YourViewModel>接口然后

this.Bind(ViewModel, vm => vm.PropertyToBind, x => comboBox.SelectedValue, comboBox.Events().SelectedValueChanged)

修改：我创建了一个演示项目：

using System; using System.Reactive.Linq; using System.Windows.Forms; using ReactiveUI; namespace WindowsFormsApplication { public partial class Form1 : Form, IViewFor<MyViewModel> { public Form1() { InitializeComponent(); ViewModel = new MyViewModel(); comboBox1.DataSource = ViewModel.Items; var selectionChanged = Observable.FromEvent<EventHandler, EventArgs>( h => (_, e) => h(e), ev => comboBox1.SelectedIndexChanged += ev, ev => comboBox1.SelectedIndexChanged += ev); this.Bind(ViewModel, vm => vm.SelectedItem, x => x.comboBox1.SelectedItem, selectionChanged); } public MyViewModel ViewModel { get; set; } object IViewFor.ViewModel { get { return ViewModel; } set { ViewModel = (MyViewModel)value; } } } public class MyItem { private readonly string _text; public MyItem(string text) { _text = text; } public override string ToString() { return _text; } } public class MyViewModel : ReactiveObject { private MyItem _selectedItem; public MyViewModel() { Items = new ReactiveList<MyItem> {new MyItem("test1"), new MyItem("test2")}; } public MyItem SelectedItem { get { return _selectedItem; } set { this.RaiseAndSetIfChanged(ref _selectedItem, value); } } public ReactiveList<MyItem> Items { get; private set; } } }

Answer 2

您可以使用Observable.FromEventPattern方法将SelectedIndexChanged事件的触发绑定到您的视图模型属性。

comboBoxWithItems.DataSource = ViewModel.ListOfPossibleItemsProperty;
comboBoxWithItems.DisplayMember = "Name";

Observable.FromEventPattern<EventHandler, EventArgs>(
    ev => comboBoxWithItems.SelectedIndexChanged += ev,
    ev => comboBoxWithItems.SelectedIndexChanged -= ev)
    .Select(x => comboBoxWithItems.SelectedItem)
    .BindTo(this, x => x.ViewModel.SelectedItemProperty);

Answer 3

您的初始vm.SelectedItem为null，并且尚未从视图更新VM。在VM构造函数中设置初始选择。

Answer 4

有关价值清单的一些改进意见：

将comboBox1.DataSource = ViewModel.Items;的直接集合替换为绑定OneWayBind(ViewModel, vm => vm.Items, v => v.comboBox1.DataSource);，以便ViewModel在视图构造函数中不存在，ViewModel可以是ReactiveBindingList动态改变。
使用ReactiveList代替{{1}}，以便WinForms绑定可以对值列表中的更改做出反应（虽然我没有尝试过这种情况）。

Answer 5

由于其他解决方案在UWP应用程序中对我不起作用，因此有一种正确的方法在WinForms，WPF和UWP应用程序中起作用：在视图的构造函数中使用Bind方法。 WPF / UWP的示例：

using ReactiveUI;
using System.Reactive.Disposables;

    public sealed partial class MyView : Page, IViewFor<MyViewModel>
    {

        public MyView()
        {
            InitializeComponent();

            this.WhenActivated(d =>
            {
                this.OneWayBind(ViewModel, vm => vm.Items, v => v.DropDownControl.ItemsSource)
                    .DisposeWith(d);

                this.Bind(ViewModel, vm => vm.SelectedItem, v => v.DropDownControl.SelectedItem)
                    .DisposeWith(d);
            });
        }


        public MyViewModel ViewModel
        {
            get => DataContext as MyViewModel;
            set => DataContext = value;
        }

        object IViewFor.ViewModel
        {
            get => ViewModel;
            set => ViewModel = value as MyViewModel;
        }
    }

在ViewModel中：

using ReactiveUI.Fody.Helpers;

    public sealed class MyViewModel : ReactiveObject
    {
        public void MyViewModel()
        {
            // Todo: Load items
        }

        [Reactive] public IList<MyItem> Items { get; set; } = new List<MyItem>();
        [Reactive] public MyItem? SelectedItem { get; set; }
    }

使用ReactiveUI和Windows窗体绑定到ComboBox

5 个答案: