How to use RelayCommand for LoadMoreCommand in .NET MAUI Chat?

The .NET MAUI Chat allows the user to use RelayCommand for LoadMoreCommand property.

XAML:

Here you can integrate the relay command for LoadMoreCommand property.

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
            xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
            xmlns:local="clr-namespace:ChatMaui"
            xmlns:sfchat="clr-namespace:Syncfusion.Maui.Chat;assembly=Syncfusion.Maui.Chat"
            x:Class="ChatMaui.MainPage">

    <ContentPage.BindingContext>
          <local:LoadMoreViewModel LoadMoreBehavior="AutoOnScroll" x:Name="viewModel"/>
    </ContentPage.BindingContext>

    <ContentPage.Content>
                <Grid RowDefinitions="Auto,*">
                      <sfchat:SfChat Grid.Row="1" x:Name="sfChat"
                                     CanAutoScrollToBottom="False"
                                     Messages="{Binding Messages}"
                                     CurrentUser="{Binding CurrentUser}" 
                                     MessageSpacing="24" 
                                     MessageShape="RoundedRectangle"
                                     LoadMoreCommand="{Binding LoadMoreItemsCommand}" 
                                     LoadMoreBehavior="{Binding LoadMoreBehavior}" 
                                     IsLazyLoading="{Binding IsBusy}">
                      </sfchat:SfChat>
                 </Grid>
      </ContentPage.Content>
</ContentPage> 

ViewModel.cs

 public partial class LoadMoreViewModel: ObservableObject, INotifyPropertyChanged
 {
        private bool isBusy = false;

        private LoadMoreOption loadMoreBehavior;

        public LoadMoreOption LoadMoreBehavior
        {
            get
            {
                return this.loadMoreBehavior;
            }
            set
            {
                this.loadMoreBehavior = value;
                this.RaisePropertyChanged("LoadMoreBehavior");
            }
        }
        
        public bool IsBusy
        {
            get { return this.isBusy; }
            set
            {
                this.isBusy = value;
                RaisePropertyChanged("IsBusy");
            }
        }
   
        #region Constructor
        public LoadMoreViewModel()
        {
            this.LoadMoreBehavior = LoadMoreOption.Auto;
        }
        #endregion

        #region Private Methods
        
        private bool CanLoadMoreItems(object obj)
        {
            // If messages are still there in the old message collection then execute the load more command.
            if (this.OldMessages.Count > 0)
            {
                return true;
            }
            else
            {
                this.LoadMoreBehavior = LoadMoreOption.None;
                IsBusy = false;
                return false;
            }

            return true;
        }

        [RelayCommand (CanExecute = nameof(CanLoadMoreItems))]
        public async void LoadMoreItems(object obj)
        {
            var chat = obj;
            try
            {
                // Set is busy as true to show the busy indicator
                this.IsBusy = true;
                await Task.Delay(3000);
                LoadMoreMessages();
            }
            catch { }
            finally
            {
                // Set is busy as false to hide the busy indicator
                IsBusy = false;
            }
        }

        private void LoadMoreMessages()
        {
            for (int i = 1; i <= 5; i++)
            {
                var oldMessage = this.OldMessages[this.OldMessages.Count - 1];
                this.Messages.Insert(0, oldMessage);
                this.OldMessages.Remove(oldMessage);
            }
        }

        #endregion
    }
}

View Sample in GitHub

Conclusion:

I hope you enjoyed learning about how to use RelayCommand for LoadMoreCommand in .NET MAUI Chat.

You can refer to our .NET MAUI SfChat feature tour page to know about its other groundbreaking feature representations and documentation, and how to quickly get started for configuration specifications.

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