I am trying to create a ListView that supports the pull to refresh feature of ListView.

My XAML is:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:Local="clr-namespace:FireLearn.ViewModels"
             x:Class="FireLearn.MainPage"
             Title="Categories">

    <ContentPage.BindingContext>
        <Local:CategoryViewModel/>
    </ContentPage.BindingContext>
    <ListView
        ItemsSource="{Binding Categories}"
        ItemSelected="ListView_ItemSelected"
        HasUnevenRows="True"
        IsPullToRefreshEnabled="True"
        IsRefreshing="{Binding ListRefreshing}"
        RefreshCommand="{Binding RefreshCommand}">
        <ListView.ItemTemplate>
            <DataTemplate>
                <ViewCell>
                    <HorizontalStackLayout
                        Padding="8">
                        <Image Source="cafs_bubbles.png"    
                               HeightRequest="64"/>
                        <VerticalStackLayout
                            Padding="8">
                            <Label Text="{Binding FormattedName}" 
                                       SemanticProperties.HeadingLevel="Level1"
                                       FontSize="Title"
                                       HorizontalOptions="Start"/>
                            <Label Text="{Binding ItemCount}" 
                                   FontSize="Subtitle"/>
                            <Label Text="{Binding Description}" 
                                   HorizontalOptions="Center"
                                   LineBreakMode="WordWrap"
                                   FontSize="Caption"
                                   VerticalOptions="CenterAndExpand"/>
                        </VerticalStackLayout>
                    </HorizontalStackLayout>
                </ViewCell>
            </DataTemplate>
        </ListView.ItemTemplate>
    </ListView>
</ContentPage>

and the code behind is:

using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Diagnostics;
using System.Reflection.Emit;
using System.Runtime.CompilerServices;
using System.Windows.Input;
using CommunityToolkit.Mvvm.ComponentModel;
using FireLearn.Models;

namespace FireLearn.ViewModels
{
    class CategoryViewModel : ObservableObject
    {
        public ObservableCollection<CategoryModel> categories = new ObservableCollection<CategoryModel>();

        public ObservableCollection<CategoryModel> Categories
        {
            get => categories;
            set => SetProperty(ref categories, value);
        }

        public bool ListRefreshing = false;

        public ICommand RefreshCommand;

        public CategoryViewModel()
        {
            loadFromSource();
            RefreshCommand = new Command(async () =>
            {
                if (!ListRefreshing)    
                {
                    ListRefreshing = true;
                    try
                    {
                        await loadFromSource();
                    }
                    finally
                    {
                        ListRefreshing = false;
                    }
                }
            });
        }
        public async Task loadFromSource()
        {
            HttpClient httpClient = new()
            {
                Timeout = new TimeSpan(0,0,10)
            };

            Uri uri = new Uri("https://somewodpresssite/wp-json/wp/v2/categories");

            HttpResponseMessage msg = await httpClient.GetAsync(uri);

            if (msg.IsSuccessStatusCode)
            {
                var result = CategoryModel.FromJson(await msg.Content.ReadAsStringAsync());
                Categories = new ObservableCollection<CategoryModel>(result);
            }

            Debug.WriteLine("List Refreshed");
        }
    }
}

The binding of the list works great and items show as expected (based on loadFromSource() being called in the constructor but the ICommand doesnt get called when I pull to refresh and I get the following error around the IsRefreshing binding:

[0:] Microsoft.Maui.Controls.Xaml.Diagnostics.BindingDiagnostics: Warning: 'ListRefreshing' property not found on 'FireLearn.ViewModels.CategoryViewModel', target property: 'Microsoft.Maui.Controls.ListView.IsRefreshing'

I have tried on Android and iOs with the same result and am at a loss as to what I've missed here.

CodePudding user response：

You can only bind to public properties

public bool ListRefreshing { get; set; }