I have this RefreshCommand which I use to refresh a database of "notes", but when I refresh the page, instead of refreshing for 2 seconds and then just giving me the notes, it keeps on refreshing, which isn't what I would like it to do, plus it lags the app.

Here is the code

MyNotePage.xaml

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
     xmlns:model="clr-namespace:MyApp.Models"
     xmlns:mvvm="clr-namespace:MvvmHelpers;assembly=MvvmHelpers"
     xmlns:viewmodels="clr-namespace:MyApp.ViewModels"
     xmlns:xct="http://xamarin.com/schemas/2020/toolkit"
     x:Class="MyApp.MyNotePage"
     x:DataType="viewmodels:MyNoteViewModel"
     BackgroundColor="White">
<ContentPage.BindingContext>
    <viewmodels:MyNoteViewModel/>
</ContentPage.BindingContext>

<ContentPage.Resources>
    <ResourceDictionary>
        <xct:ItemSelectedEventArgsConverter x:Key="ItemSelectedEventArgsConverter"/>
    </ResourceDictionary>
</ContentPage.Resources>

<ContentPage.ToolbarItems>
    <ToolbarItem Text="Add" Command="{Binding AddCommand}"/>
</ContentPage.ToolbarItems>

<ListView
BackgroundColor="Transparent"
CachingStrategy="RecycleElement"
HasUnevenRows="True"
IsPullToRefreshEnabled="True"
IsRefreshing="{Binding IsBusy, Mode=OneWay}"
ItemsSource="{Binding Note}"
RefreshCommand="{Binding RefreshCommand}"
RefreshControlColor="DarkViolet"
SelectionMode="None"
SeparatorVisibility="None">
    <ListView.ItemTemplate>
        <DataTemplate x:DataType="model:Note">
            <ViewCell>
                <ViewCell.ContextActions>
                    <MenuItem
                    Command="{Binding Source={Binding MyNotePage}, Path=BindingContext.RemoveCommand}"
                    CommandParameter="{Binding .}"
                    IsDestructive="True"
                    Text="Delete"/>
                </ViewCell.ContextActions>
                <Grid Padding="10">
                    <Frame CornerRadius="20" HasShadow="True">
                        <StackLayout Orientation="Horizontal">
                            <StackLayout VerticalOptions="Center">
                                <Label
                                FontSize="Large"
                                Text="{Binding Name}"
                                VerticalOptions="Center"/>
                                <Label
                                FontSize="Small"
                                Text="{Binding Id}"
                                VerticalOptions="Center"/>
                            </StackLayout>
                        </StackLayout>
                    </Frame>
                </Grid>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

MyNotePage.xaml.cs

namespace MyApp
{

    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class MyNotePage
    {
        public MyNotePage()
        {
            InitializeComponent();
        }


    }
}

MyNoteViewModel.cs

namespace MyApp.ViewModels
{
    public class MyNoteViewModel : ViewModelBase
    {

        public ObservableRangeCollection<Note> Note { get; }
        public AsyncCommand RefreshCommand { get; }

        public AsyncCommand AddCommand { get; }

        public AsyncCommand<Note> RemoveCommand { get; }
        public new bool IsBusy { get; private set; }

        public MyNoteViewModel()
        {

            Note = new ObservableRangeCollection<Note>();

            RefreshCommand = new AsyncCommand(Refresh);
            AddCommand = new AsyncCommand(Add);
            RemoveCommand = new AsyncCommand<Note>(Remove);
        }

        async Task Add()
        {
            var name = await App.Current.MainPage.DisplayPromptAsync("Notes", "Enter your notes here");
            await NoteService.AddNote(name);
            await Refresh();
        }

        async Task Remove(Note note)
        {
            await NoteService.RemoveNote(note.Id);
            await Refresh();
        }


        async Task Refresh()
        {
            IsBusy = true;
            await Task.Delay(2000);
            Note.Clear();
            var notes = await NoteService.GetNote();
            Note.AddRange(notes);
            IsBusy = false;
        }
    }
}

And NoteService.cs

namespace MyApp.Services
{
    public static class NoteService
    {

        static SQLiteAsyncConnection db;
        static async Task Init()
        {

            if (db != null)
                return;
            {
                var databasePath = Path.Combine(FileSystem.AppDataDirectory, "MyData.db");

                db = new SQLiteAsyncConnection(databasePath);

                await db.CreateTableAsync<Note>();
            }
        }

        public static async Task AddNote(string name)
        {
            await Init();
            var note = new Note()
            {
                Name = name,
            };

            await db.InsertAsync(note);

        }
        public static async Task RemoveNote(int id)
        {
            await Init();
            await db.DeleteAsync<Note>(id);

        }
        public static async Task<IEnumerable<Note>> GetNote()
        {
            await Init();

            var note = await db.Table<Note>().ToListAsync();
            return note;

        }

    }
}

Maybe it is something to do with IsBusy? I don't know if I set that up properly. The bool does change from false to true but it looks like it doesn't do the opposite to stop the refresh. Thanks for the help.

Edit : I fixed it, the lines public new bool IsBusy { get; private set; } were unnecessary and it actually prohibited IsBusy from functioning properly.

CodePudding user response：

I pointed this out to you in your previous question. IsBusy does not raise a PropertyChanged event so the UI is never notified