如何将列表中的单选按钮状态设置为数据绑定？ [英] How do I get the state of radio buttons inside a list to data-bind?

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问题描述

遵循MVVM模式，我有一个包含单选按钮的列表，其状态绑定到视图模型中项目列表中的布尔属性。我有逻辑在视图模型中进行更改，但我无法让UI识别这些更改。



我在网上找到了这个问题的变种但是找不到像我的例子一样简单。我不想让代码过于复杂，所以我希望有一个简单的解决方案。



我的实际代码太大而无法发布，但我设法构建了以下显示相同行为的最小示例。



我的XAML：



< Window x：Class =WpfApplication2.MainWindow
 xmlns =http://schemas.microsoft.com/winfx/2006/xaml/presentation
 xmlns： x =http://schemas.microsoft.com/winfx/2006/xaml
 xmlns：d =http://schemas.microsoft.com/expression/blend/2008
 xmlns： mc =http://schemas.openxmlformats.org/markup-compatibility/2006
 xmlns：local =clr-namespace：WpfApplication2
 mc：Ignorable =d
 Title =MainWindow高度=350宽度=525> 
 
< Control.Resources> 
< ResourceDictionary> 
< DataTemplate x：Key =ProgressTrackingDataTemplate> 
< Grid Margin =0> 
< Grid.RowDefinitions> 
< RowDefinition Height =Auto/> 
< /Grid.RowDefinitions> 
< Grid.ColumnDefinitions> 
< ColumnDefinition Width =*/> 
< ColumnDefinition Width =Auto/> 
< /Grid.ColumnDefinitions> 
< Label Grid.Row =0Grid.Column =0Content ={Binding Name}Margin =0Padding =2,2,2,2/> 
< Viewbox Grid.Row =0Grid.Column =1Height =20> 
< RadioButton IsChecked ={Binding State，Mode = TwoWay}/> 
< / Viewbox> 
< / Grid> 
< / DataTemplate> 
< Style x：Key =ProgressTrackingListBoxItemStyleTargetType =ListBoxItem> 
< Setter Property =Horizo​​ntalContentAlignmentValue =Stretch/> 
< Setter Property =FocusableValue =False/> 
< / Style> 
< / ResourceDictionary> 
< /Control.Resources> 
 
< Grid> 
< Grid.RowDefinitions> 
< RowDefinition /> 
< RowDefinition Height =30/> 
< /Grid.RowDefinitions> 
< Grid.ColumnDefinitions> 
< ColumnDefinition /> 
< /Grid.ColumnDefinitions> 
< ListView Grid.Row =0Grid.Column =0
 ItemsSource ={Binding ProgressValues}
 ItemTemplate ={StaticResource ProgressTrackingDataTemplate}
 ItemContainerStyle ={StaticResource ProgressTrackingListBoxItemStyle}/> 
< Button Grid.Row =1Grid.Column =0Content =Change selected itemClick =Button_Click/> 
< / Grid> 
< / Window>





代码隐藏：



  public   partial   class  MainWindow：Window 
 {
  public  MainWindow（）
 {
 InitializeComponent（）; 
 DataContext = _myViewModel; 
} 
  private   void  Button_Click（ object  sender，RoutedEventArgs e）
 {
 _myViewModel.ChangeSelectedItem（）; 
} 
  private  MyViewModel _myViewModel =  new  MyViewModel（）; 
}





视图型号：



< pre lang =c＃> 使用 System.Collections.Generic;
使用 System.ComponentModel;

命名空间 WpfApplication2
{
public class ProgressValue
{
public string 名称{获取; set ; } = ;
public bool 状态{获取; set ; } = false ;
}

public class MyViewModel：INotifyPropertyChanged
{
public MyViewModel（）
{
_progressValues [_selectedItemIndex] .State = true ;
}

public event PropertyChangedEventHandler PropertyChanged;

public 列表< ProgressValue> ProgressValues { get { return _progressValues; }

public void ChangeSelectedItem（）
{
_selectedItemIndex ++;
if （_selectedItemIndex == _progressValues.Count）
_selectedItemIndex = 0 ;
foreach （ var progressValue in _progressValues）
progressValue.State = false ;
_progressValues [_selectedItemIndex] .State = true ;
PropertyChanged？.Invoke（ this ， new PropertyChangedEventArgs（ nameof （ProgressValues）））;
}

private int _selectedItemIndex = 0 ;

private 列表< ProgressValue> _progressValues = new 列表< ProgressValue>（）
{
new ProgressValue（） {Name = 未开始，State = false }，
new ProgressValue（）{Name = 正在进行，State = false }，
new ProgressValue（）{Name = 已完成，State = false }，
new ProgressValue（）{Name = 已开票，状态= false }
};
}
}





请注意，我在视图模型的构造函数中执行的初始选择是反映在用户界面中，这意味着必须有办法让这个工作。



任何帮助都将非常感激。

< br $>
亲切的愿望~Patrick



我尝试过：



我尝试过在一个小组中使用单选按钮但没有将它们放在一个小组中。



我尝试了各种方法来提高 PropertyChanged 事件，包括在 PropertyChangedEventArgs 中传递一个空字符串，我认为这是一种告诉用户界面重新评估所有内容的方法绑定？

解决方案

如评论中所述， ProgressValue 类需要实现 INotifyPropertyChanged ，并在州属性更改时引发 PropertyChanged 事件。

 public class ProgressValue：INotifyPropertyChanged 
 {
 private bool _state; 
 
公共事件PropertyChangedEventHandler PropertyChanged; 
 
 public string Name {get;组; } =; 
 
 public bool State 
 {
 get 
 {
 return _state; 
} 
设置
 {
 _state = value; 
 PropertyChanged？.Invoke（this，new PropertyChangedEventArgs（nameof（State）））; 
} 
} 
}


Following the MVVM pattern, I have a list that contains radio buttons, the state of which is bound to a boolean property in a list of items in the view-model. I have logic that makes changes in the view-model, but I cannot get the UI to recognise these changes.

I have found variations of this problem online but cannot find anything as simple as my example. I don't want to over-complicate the code, so I am hoping there is a simple solution to this.

My real code is way too big to post, but I have managed to construct the following minimal example that shows the same behaviour.

My XAML:

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApplication2"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">

	<Control.Resources>
		<ResourceDictionary>
			<DataTemplate x:Key="ProgressTrackingDataTemplate">
				<Grid Margin="0">
					<Grid.RowDefinitions>
						<RowDefinition Height="Auto"/>
					</Grid.RowDefinitions>
					<Grid.ColumnDefinitions>
						<ColumnDefinition Width="*"/>
						<ColumnDefinition Width="Auto"/>
					</Grid.ColumnDefinitions>
					<Label Grid.Row="0" Grid.Column="0" Content="{Binding Name}" Margin="0" Padding="2,2,2,2"/>
					<Viewbox Grid.Row="0" Grid.Column="1" Height="20">
						<RadioButton IsChecked="{Binding State,Mode=TwoWay}"/>
					</Viewbox>
				</Grid>
			</DataTemplate>
			<Style x:Key="ProgressTrackingListBoxItemStyle" TargetType="ListBoxItem">
				<Setter Property="HorizontalContentAlignment" Value="Stretch"/>
				<Setter Property="Focusable" Value="False"/>
			</Style>
		</ResourceDictionary>
	</Control.Resources>

	<Grid>
		<Grid.RowDefinitions>
			<RowDefinition/>
			<RowDefinition Height="30"/>
		</Grid.RowDefinitions>
		<Grid.ColumnDefinitions>
			<ColumnDefinition/>
		</Grid.ColumnDefinitions>
		<ListView Grid.Row="0" Grid.Column="0"
			ItemsSource="{Binding ProgressValues}"
			ItemTemplate="{StaticResource ProgressTrackingDataTemplate}"
			ItemContainerStyle="{StaticResource ProgressTrackingListBoxItemStyle}"/>
		<Button Grid.Row="1" Grid.Column="0" Content="Change selected item" Click="Button_Click"/>
	</Grid>
</Window>



The code-behind:

public partial class MainWindow : Window
{
	public MainWindow()
	{
		InitializeComponent();
		DataContext = _myViewModel;
	}
	private void Button_Click( object sender, RoutedEventArgs e )
	{
		_myViewModel.ChangeSelectedItem();
	}
	private MyViewModel _myViewModel = new MyViewModel();
}



The view-model:

using System.Collections.Generic;
using System.ComponentModel;

namespace WpfApplication2
{
	public class ProgressValue
	{
		public string Name { get; set; } = "";
		public bool State { get; set; } = false;
	}

	public class MyViewModel : INotifyPropertyChanged
	{
		public MyViewModel()
		{
			_progressValues[ _selectedItemIndex ].State = true;
		}

		public event PropertyChangedEventHandler PropertyChanged;

		public List<ProgressValue> ProgressValues { get { return _progressValues; } }

		public void ChangeSelectedItem()
		{
			_selectedItemIndex++;
			if( _selectedItemIndex == _progressValues.Count )
				_selectedItemIndex = 0;
			foreach( var progressValue in _progressValues )
				progressValue.State = false;
			_progressValues[ _selectedItemIndex ].State = true;
			PropertyChanged?.Invoke( this, new PropertyChangedEventArgs( nameof(ProgressValues) ) );
		}

		private int _selectedItemIndex = 0;

		private List<ProgressValue> _progressValues = new List<ProgressValue>()
		{
			new ProgressValue() { Name = "Not Started", State = false },
			new ProgressValue() { Name = "Underway", State = false },
			new ProgressValue() { Name = "Completed", State = false },
			new ProgressValue() { Name = "Invoiced", State = false }
		};
	}
}



Note that the initial selection that I perform in the constructor of the view-model is reflected in the UI, which implies there must be a way to get this working.

Any help would be very much appreciated.

Kind wishes ~ Patrick

What I have tried:

I have tried having the radio buttons in a group and not having them in a group.

I have tried various ways to raise the PropertyChanged event, including passing an empty string in the PropertyChangedEventArgs, which I thought was a way to tell the UI to re-evaluate all bindings?

解决方案

As mentioned in the comments, the ProgressValue class needs to implement INotifyPropertyChanged, and raise the PropertyChanged event when the State property changes.

public class ProgressValue : INotifyPropertyChanged
{
    private bool _state;
    
    public event PropertyChangedEventHandler PropertyChanged;
    
    public string Name { get; set; } = "";
    
    public bool State 
    { 
        get
        {
            return _state;
        }
        set
        {
            _state = value;
            PropertyChanged?.Invoke( this, new PropertyChangedEventArgs( nameof(State) ) );
        }
    }
}


这篇关于如何将列表中的单选按钮状态设置为数据绑定？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

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