[Solved] RadGridView.HasItems is false when the Visibility is set to Collapsed

[Geoff Hardy]

We have a RadGridView that we only want to display whenever it has some rows. When I has no rows, its visibility should be collapsed. However if we bind its visibility to the HasItems property, HasItems always seems to evaulate to false when the Visibility is set to Collapsed. Is this intentional or a bug? Is there a workaround to determine if there are items in a grid, regardless of whether or not it is visible?

[Vlad]

Hi,

The grid will not be bound if the Visibility is set to Collapsed and that is why HasItems will be false. You can create addition property to your view model to achieve the desired result:

XAML

<UserControl x:Class="SilverlightApplication1.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480"
    xmlns:telerik="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls"
    xmlns:telerikGrid="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.GridView">
    <Grid x:Name="LayoutRoot">
        <Grid.Resources>
            <telerik:BooleanToVisibilityConverter x:Key="converter" />
        </Grid.Resources>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition />
        </Grid.RowDefinitions>
        <Button Content="Clear" Click="Button_Click" />
        <telerikGrid:RadGridView Grid.Row="1" ItemsSource="{Binding Data}"
                                 Visibility="{Binding HasItems, Converter={StaticResource converter}}" />
    </Grid>
</UserControl>

C#

using System;
using System.Linq;
using System.Collections;
using System.ComponentModel;
using System.Windows.Controls;
using System.Collections.Generic;
using System.Collections.ObjectModel;

namespace SilverlightApplication1
{
    public partial class MainPage : UserControl
    {
        public MainPage()
        {
            InitializeComponent();

            DataContext = new MyDataContext();
        }

        private void Button_Click(object sender, System.Windows.RoutedEventArgs e)
        {
            ((MyDataContext)DataContext).ClearData();
        }
    }

    public class MyDataContext : INotifyPropertyChanged
    {
        ObservableCollection<MyObject> _Data;
        public ObservableCollection<MyObject> Data
        {
            get
            {
                if (_Data == null)
                {
                    _Data = new ObservableCollection<MyObject>();
                    (from i in Enumerable.Range(0, 100)
                     select new MyObject() { ID = i, Name = String.Format("Name{0}", i) }).ToList().ForEach(_Data.Add);
                }

                return _Data;
            }
        }

        public void ClearData()
        {
            Data.Clear();
            this.OnPropertyChanged("HasItems");
        }

        public bool HasItems
        {
            get
            {
                return Data.Any();
            }
        }

        #region INotifyPropertyChanged Members

        private void OnPropertyChanged(string propertyName)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        #endregion
    }

    public class MyObject
    {
        public int ID { get; set; }
        public string Name { get; set; }
    }
}

Sincerely yours,
Vlad
the Telerik team

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