how-to-use-relay-command-on-LoadMore-command-of-chat-dotnet-maui

This repository contains a sample demonstrating how to use RelayCommand for LoadMore Command in .NET MAUI Chat SfChat. The .NET MAUI Chat allows the user to use RelayCommand for LoadMore Command of SfChat

XAML:

You can integrate the relay command for LoadMore

<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
    }
}

Requirements to run the demo

To run the demo, refer to System Requirements for .NET MAUI

Troubleshooting:

Path too long exception

If you are facing path too long exception when building this example project, close Visual Studio and rename the repository to short and build the project.

License

Syncfusion® has no liability for any damage or consequence that may arise from using or viewing the samples. The samples are for demonstrative purposes. If you choose to use or access the samples, you agree to not hold Syncfusion® liable, in any form, for any damage related to use, for accessing, or viewing the samples. By accessing, viewing, or seeing the samples, you acknowledge and agree Syncfusion®'s samples will not allow you seek injunctive relief in any form for any claim related to the sample. If you do not agree to this, do not view, access, utilize, or otherwise do anything with Syncfusion®'s samples.