GroupDescriptor changed MVVM method?

2 posts, 0 answers
  1. Jasper
    Jasper avatar
    8 posts
    Member since:
    Dec 2015

    Posted 17 May 2016 Link to this post

    Hi there

    Is there an MVVM-pattern solution to trigger a ViewModel refresh (from an rpc-database backend) when the groupdescriptors of a DataGird are changed?

    Right now I've solved this issue with a C# event as below, but I'd like to have either the groupdescriptors bound to the viewmodel or I'd like to use an ICommand following MVVM principles.

    Current solution:

    dataGrid.GroupDescriptors.CollectionChanged += GroupDescriptors_CollectionChanged;
    private void GroupDescriptors_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        string groups = "";
        foreach (Telerik.Data.Core.PropertyGroupDescriptor gridGroup in dataGrid.GroupDescriptors)
            groups += (String.IsNullOrWhiteSpace(groups) ? "" : ",") +
                ((gridGroup.SortOrder == Telerik.Data.Core.SortOrder.Ascending) ? "+" : "-") +
        This.ViewModel.GroupStringForRpcCall = groups;


    Desired solution following MVVM principles:

    <gridCommands:DataGridUserCommand Id="ColumnHeaderTap" EnableDefaultCommand="True" Command="{Binding TelerikColumnHeaderSortCommand, Source={StaticResource ViewModel}}" />

    internal class TelerikRpcSortCommand : ICommand
        private IRpcViewModel ViewModel;
        public TelerikRpcSortCommand(IRpcViewModel viewModel)
            ViewModel = viewModel;
        public event EventHandler CanExecuteChanged;
        public bool CanExecute(object parameter)
            var context = parameter as ColumnHeaderTapContext;
            return true;
        public async void Execute(object parameter)
            var context = parameter as ColumnHeaderTapContext;
            var column = context.Column as DataGridTypedColumn;         
            string order = null;
            if (column.SortDirection == SortDirection.Ascending)
                order = "+" +column.PropertyName;
            else if (column.SortDirection == SortDirection.Descending)
                order = "-" + column.PropertyName;
                order = "";
            ViewModel.Order = order;


  2. Ivaylo Gergov
    Ivaylo Gergov avatar
    691 posts

    Posted 20 May 2016 Link to this post

    Hi Jasper,

    Thank you for your interest.

    Currently, RadDataGrid does not expose a command for the grouping action so such approach could not be possible. Here are all the supported commands. I will log this as a feature request.

    Please, let me know should you need further assistance.
    Ivaylo Gergov
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