视图模型中RadioBox set GroupName的Xamarin列表

Question

到目前为止，我找到的所有RadioButtons示例都在页面的xaml中硬编码了值。我希望从数据库中提供字符串列表(目前)，并遇到GroupName的问题。

My data template for a radio display type:
<DataTemplate x:Key="RadioTemplate">
<StackLayout>
<Label 
Text="{Binding Name}"
Style="{StaticResource LabelStyle}">
</Label>
<ListView ItemsSource="{Binding Choices.Choices}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<RadioButton Value="{Binding}"
Content="{Binding}"
GroupName="someGroupName"
CheckedChanged="OnRadioChanged">
</RadioButton>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</DataTemplate>

MainPageViewModel.cs
using System;
using System.Collections.ObjectModel;
using System.Windows.Input;
using Xamarin.Forms;
using FieldDataTemplateSelectorSample.Validations;
namespace FieldDataTemplateSelectorSample
{
public class MainPageViewModel : ValidationViewModelBase
{
public MainPageViewModel()
{
_fields = new ObservableCollection<FieldViewModel>();
}
private ObservableCollection<FieldViewModel> _fields;
public ObservableCollection<FieldViewModel> Fields
{
get { return _fields; }
set
{
_fields = value;
RaisePropertyChanged();
}
}
private bool _showValidationSummary;
public bool ShowValidationSummary
{
get { return _showValidationSummary; }
set
{
_showValidationSummary = value;
RaisePropertyChanged();
}
}
ICommand _submitCommand;
public ICommand SubmitCommand
{
get => _submitCommand ?? (_submitCommand = new Command(ValidateAndSave));
}
private void ValidateAndSave(object obj)
{
ValidateAll();
if (ErrorStateManager.HasError)
{
ShowValidationSummary = true;
}
else
{
ShowValidationSummary = false;
}
}
}
}
using System.Collections.Generic;
using Xamarin.Forms;
using FieldDataTemplateSelectorSample.Validations;

namespace FieldDataTemplateSelectorSample
{
public class FieldViewModel : ValidationViewModelBase
{
public FieldViewModel()
{
_choices = new ChoiceViewModel();
}
private string _value;
public long Id { get; set; }
public string Name { get; set; }
public string Title { get; set; }
public string Code { get; set; }
public string Value 
{ 
get
{
return _value;
}           
set
{
_value = value;
RaisePropertyChanged();
Validate();
}
}
public string PlaceholderText { get; set; }
public int SortOrder { get; set; }
public string DisplayType { get; set; }
public bool IsReadOnly { get; set; }
public bool IsEnabled { get; set; }
private ChoiceViewModel _choices;
public ChoiceViewModel Choices
{
get 
{ 
return _choices; 
}
set 
{ 
_choices = value; 
RaisePropertyChanged(); 
}
}
void OnChoicesRadioButtonCheckedChanged(object sender, CheckedChangedEventArgs e)
{
// what else do we need to do?  Update value?

RaisePropertyChanged();
}
}
}
using System;
using System.Collections.Generic;
using System.Text;
namespace FieldDataTemplateSelectorSample
{
public class ChoiceViewModel
{
public ChoiceViewModel()
{
Choices = new List<string>();
}
public string Code { get; set; }
public List<string> Choices { get; set; }
}
}

只要我在ViewCell中为RadioButton硬编码GroupName，一切都可以工作，但是我最终会为页面上的每个单选按钮都设置一个组名。我试过在模板中添加属性到StackLayout:

<StackLayout RadioButtonGroup.GroupName="someGroup">

并将其从RadioButton中取出，但当我在OnRadioChanged中放置断点时，GroupName将作为null进入。

我想在ChoiceViewModel中使用Code属性作为组名，但还没有得到正确的相对绑定。如果有任何关于绑定的帮助，或者用不同的方式来做DataTemplate，我们将不胜感激。

Answer 1

你可以使用一个可绑定的StackLayout，这将给你更多的控制容器

<StackLayout>
<Label Text="{Binding Name}" Style="{StaticResource LabelStyle}" />
<StackLayout RadioButtonGroup.GroupName="{Binding Name}"      
BindableLayout.ItemsSource="{Binding Choices.Choices}" >
<BindableLayout.ItemTemplate>
<DataTemplate>
<ViewCell>
<RadioButton Value="{Binding}" Content="{Binding}"
CheckedChanged="OnRadioChanged" />
</ViewCell>
</DataTemplate>
</BindableLayout.ItemTemplate>
</StackLayout>
</StackLayout>