[Solved] Strange behaviour of ComboBoxColumn after changing the column

[Lukas]

Hi. When the RadGridView initializes, everything seems alright. The columns records are shown properly.

As soon as I click somewhere on a column and switch it again all the content of the previous column hides. As soon as I click on it again, the content appears, again. Here my code + screenshots:

C#:

using System;
using System.Collections.ObjectModel;

namespace RadGridViewTest2
{
    public partial class MainPage
    {
        public ObservableCollection<MyListEntry> MyListEntries { get; set; }
        public ObservableCollection<OtherEntry> OtherEntries { get; set; }
        public ObservableCollection<Record> Records { get; set; }
        public Record SelectedRecord { get; set; }

        public MainPage()
        {
            InitializeComponent();
            MyListEntries = new ObservableCollection<MyListEntry>();
            OtherEntries = new ObservableCollection<OtherEntry>();
            Records = new ObservableCollection<Record>();

            for (int i = 0; i < 15; i++)
            {
                MyListEntries.Add(new MyListEntry
                    {
                        Id = Guid.NewGuid(),
                        Name = "MyListEntry" + i
                    });
                OtherEntries.Add(new OtherEntry
                    {
                        Id = Guid.NewGuid(),
                        Name = "OtherEntry" + i,
                        Description = "NewDescription" + i
                    });
            }

            var r = new Random();
            for (int i = 0; i < 100; i++)
            {
                Records.Add(new Record
                    {
                        Name = "Record" + i,
                        MyListEntry = MyListEntries[r.Next(14)],
                        OtherEntry = OtherEntries[r.Next(14)]
                    });
            }
            DataContext = this;
        }
    }

    public class MyListEntry
    {
        public Guid Id { get; set; }
        public string Name { get; set; }
    }

    public class OtherEntry
    {
        public Guid Id { get; set; }
        public string Name { get; set; }
        public string Description { get; set; }
    }

    public class Record
    {
        public string Name { get; set; }
        public MyListEntry MyListEntry { get; set; }
        public OtherEntry OtherEntry { get; set; }
    }
}

XAML:

<UserControl x:Class="RadGridViewTest2.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"
        xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
        mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480">
    <Grid x:Name="LayoutRoot">
        <telerik:RadGridView ItemsSource="{Binding Records}" SelectedItem="{Binding SelectedRecord}" AutoGenerateColumns="False">
            <telerik:RadGridView.Columns>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding Name}" Header="Name" />
                <telerik:GridViewComboBoxColumn ItemsSource="{Binding MyListEntries, Mode=OneTime}" DisplayMemberPath="Name"
                                                DataMemberBinding="{Binding MyListEntry, Mode=TwoWay}" Header="MyListEntry"/>
                <telerik:GridViewComboBoxColumn ItemsSource="{Binding OtherEntries, Mode=OneTime}"
                                                DataMemberBinding="{Binding OtherEntry, Mode=TwoWay}" Header="OtherEntry" DisplayMemberPath="Name" />
            </telerik:RadGridView.Columns>
        </telerik:RadGridView>
    </Grid>
</UserControl>

Help would be greatly appreciated

[Dimitrina]

Hello,

 Thank you for the code snippets. 

I would suggest you to check this help article for further instructions on how to resolve the problem. 

All the best,
Didie
the Telerik team

[Lukas]

Sorry, I resolved my problem already with help of this link. But as I also mentioned in this post, I write it again in here:

You provided this help article. One suggestion was "1. Expose the ViewModel as a static resource on the page so that it can be easily accessible by the binding". We've been using this for quite some time - but if I remember right, you need to make these lists static, as well, which makes everything quite unhandy. I think since SL5 the approach via RelativeSource is way more elegant. Like this:

<telerik:GridViewComboBoxColumn Header="Category"
            DataMemberBinding="{Binding CategoryID}"
            ItemsSource="{Binding DataContext.Categories, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=UserControl}}"
            DisplayMemberPath="CategoryName"
            SelectedValueMemberPath="CategoryID" />

This requires that the UsersControls DataContext is properly set.