Adding a command to a radiobutton in a ListView - xamarin.forms

Question

I've a ListView which iterates over a number of questions which the end user is required to answer with radiobuttons or checkboxes.
The ViewModel specifies "TheQuestions" as:
TheQuestions = new ObservableCollection<Question>();
TheQuestions.Add(new Question
{
Id = 123,
Attribute1 = Value1,
TheQuestion = "Blah blah?",
Answer = false,
});
The ListView looks like this:
<ListView ItemsSource="{Binding TheQuestions, Mode=TwoWay}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout>
<Label Text="{Binding TheQuestion}" />
<StackLayout Orientation="Horizontal">
<RadioButton Command="{ ?? }" CommandParameter="{Binding .}" GroupName="{Binding Id,Mode=TwoWay}" Text="Yes" TextColor="Green" />
<RadioButton Command="{Binding ??}" GroupName="{Binding Id, Mode=TwoWay}" Text="No" TextColor="Red" />
</StackLayout>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
Later on I will add checkboxes and entries as well to a number of questions. I'm struggling when comes to populating my viewmodel with the selected answer. Is it doable or should I consider another approach?

Answer 1

You could binding the RadioButton's command directly to ViewModel so that you don't need to define it in Model multi-times .
in Xaml
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:local="clr-namespace:App32"
x:Class="App32.MainPage"
x:Name="Page" // set name of ContentPage
>
<RadioButton Command="{Binding Source={x:Reference Page}, Path=BindingContext.RadioCommand}" CommandParameter="{Binding .}" GroupName="{Binding Id,Mode=TwoWay}" Text="Yes" TextColor="Green" />
<RadioButton Command="{Binding Source={x:Reference Page}, Path=BindingContext.RadioCommand}" CommandParameter="{Binding .}" GroupName="{Binding Id, Mode=TwoWay}" Text="No" TextColor="Red" />
In your ViewModel
public ICommand RadioCommand { get; set; }
public xxxViewModel()
{
TheQuestions = new ObservableCollection<Question>();
TheQuestions.Add(new Question
{
Id = 123,
Attribute1 = Value1,
TheQuestion = "Blah blah?",
Answer = false,
});
RadioCommand = new Command((obj)=> {
var model = obj as Question;
var answer = model.Answer;
//do something you want
});
}