Using bindings to control column order in a DataGrid
- by DanM
Problem
I have a WPF Toolkit DataGrid, and I'd like to be able to switch among several preset column orders. This is an MVVM project, so the column orders are stored in a ViewModel. The problem is, I can't get bindings to work for the DisplayIndex property. No matter what I try, including the sweet method in this Josh Smith tutorial, I get:
The DisplayIndex for the DataGridColumn with Header 'ID' is out of range. DisplayIndex must be greater than or equal to 0 and less than Columns.Count. Parameter name: displayIndex. Actual value was -1.
Is there any workaround for this?
I'm including my test code below. Please let me know if you see any problems with it.
ViewModel code
public class MainViewModel
{
public List<Plan> Plans { get; set; }
public int IdDisplayIndex { get; set; }
public int NameDisplayIndex { get; set; }
public int DescriptionDisplayIndex { get; set; }
public MainViewModel()
{
Initialize();
}
private void Initialize()
{
IdDisplayIndex = 1;
NameDisplayIndex = 2;
DescriptionDisplayIndex = 0;
Plans = new List<Plan>
{
new Plan { Id = 1, Name = "Primary", Description = "Likely to work." },
new Plan { Id = 2, Name = "Plan B", Description = "Backup plan." },
new Plan { Id = 3, Name = "Plan C", Description = "Last resort." }
};
}
}
Plan Class
public class Plan
{
public int Id { get; set; }
public string Name { get; set; }
public string Description { get; set; }
}
Window code - this uses Josh Smith's DataContextSpy
<Window
x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication1"
xmlns:mwc="http://schemas.microsoft.com/wpf/2008/toolkit"
Title="Main Window" Height="300" Width="300">
<Grid>
<mwc:DataGrid ItemsSource="{Binding Plans}" AutoGenerateColumns="False">
<mwc:DataGrid.Resources>
<local:DataContextSpy x:Key="spy" />
</mwc:DataGrid.Resources>
<mwc:DataGrid.Columns>
<mwc:DataGridTextColumn
Header="ID"
Binding="{Binding Id}"
DisplayIndex="{Binding Source={StaticResource spy}, Path=DataContext.IdDisplayIndex}" />
<mwc:DataGridTextColumn
Header="Name"
Binding="{Binding Name}"
DisplayIndex="{Binding Source={StaticResource spy}, Path=DataContext.NameDisplayIndex}" />
<mwc:DataGridTextColumn
Header="Description"
Binding="{Binding Description}"
DisplayIndex="{Binding Source={StaticResource spy}, Path=DataContext.DescriptionDisplayIndex}" />
</mwc:DataGrid.Columns>
</mwc:DataGrid>
</Grid>
</Window>
Note: If I just use plain numbers for DisplayIndex, everything works fine, so the problem is definitely with the bindings.
Update 5/1/2010
I was just doing a little maintenance on my project, and I noticed that when I ran it, the problem I discuss in this post had returned. I knew that it worked last time I ran it, so I eventually narrowed the problem down to the fact that I had installed a newer version of the WPF Toolkit (Feb '10). When I reverted to the June '09 version, everything worked fine again. So, I'm now doing something I should have done in this first place: I'm including the WPFToolkit.dll that works in my solution folder and checking it into version control. It's unfortunate, though, that the newer toolkit has a breaking change.
