System.ArgumentOutOfRangeException when setting RadioButton IsChecked in MAUI

Question

I am making a property app where I have one file for LandingPage.cs and another for LandingViewModel.cs. The goal is to bind a list of sections to radio buttons and set the first radio button as checked. However, I encounter an error when trying to set the first radio button as checked. Here is my code:

// LandingViewModel.cs
using PropertyApp.Model;
using PropertyApp.View;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;

namespace PropertyApp.ViewModel
{
    public class LandingViewModel : BaseViewModel
    {
        public List<string> Sections = new List<string> { "Trending", "Popular", "Buy", "Rent" };

        public List<Property> Properties => PropertyRepo.AllProperties;

        public Property SelectedProperty { get; set; }

        public ICommand PropertySelected => new Command(obj =>
        {
            if (SelectedProperty != null)
                Application.Current.MainPage.Navigation.PushAsync(new DetailsPage(SelectedProperty));
            SelectedProperty = null;
        });
    }
}

// LandingPage.cs
using PropertyApp.ViewModel;

namespace PropertyApp.View
{
    public partial class LandingPage : ContentPage
    {
        public LandingPage()
        {
            InitializeComponent();
            this.BindingContext = new LandingViewModel();
            (SectionList.Children[0] as RadioButton).IsChecked = true;
        }
    }
}

using this line

(SectionList.Children[0] as RadioButton).IsChecked = true;

Got this error System.ArgumentOutOfRangeException: 'Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index')

Can anyone tell me where I am going wrong? I want to activate the radio buttons for the list of sections given, but in the Android emulator, the buttons are not showing.

Answer 1

Unlike your Properties object, your SectionList is not updating the value sent to the UI

So this line

public List<string> Sections = new List<string> { "Trending", "Popular", "Buy", "Rent" };

should be

public List<string> Sections => new List<string> { "Trending", "Popular", "Buy", "Rent" };