使用ComboBox和ReactiveUI窗体绑定到ReactiveUI

Question

我希望使用ComboBox将视图模型中的属性绑定到Windows应用程序中的ReactiveUI。

我在WPF中找到了几个示例，但没有找到Windows窗体的示例。

编辑:第1部分:将选定的值绑定到注释中的以下示例：

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

我得到了错误：CS1955 Non-invocable member 'Component.Events' cannot be used like a method.

第2部分:将ComboBox中的项绑定到视图模型中的集合？不知道怎么做

Answer 1

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

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 2

首先，视图应该实现IViewFor<YourViewModel>接口，然后再实现

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

编辑：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 3

您的初始vm.SelectedItem为空，并且还没有从视图中更新VM的任何更改。在VM构造函数中设置初始选择。