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Calculated columns

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GridView

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answered on 20 Jul 2009, 08:37 AM

ticketid-228472-calculatedcolumns.zip

Hello Daniel Nevers,

This can be easily achieved by harnessing the power of the IValueConverter. I have prepared a small sample project that demonstrates how to do this. My business entity is a football club and has a name, date of establishment, stadium capacity and ticket price. We will add a calculated column which will show the ticket revenue that the clubs will get when the park is completely sold out. Here is the XAML defining the "normal" columns and finally the calculated one:

    
            <Window x:Class="TicketID_228472_CalculatedColumns.Window1" 
        
                xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
        
                xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        
                xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation" 
        
                xmlns:local="clr-namespace:TicketID_228472_CalculatedColumns" 
        
                Title="Window1"> 
        
                <Grid> 
        
                    <Grid.Resources> 
        
                        <local:ClubToSelloutRevenueConverter x:Key="clubToSelloutRevenueConverter"/> 
        
                    </Grid.Resources> 
        
                    <telerik:RadGridView  
        
                        Name="clubsGrid"  
        
                        Grid.Row="0" 
        
                        AutoGenerateColumns="False" 
        
                        ColumnsWidthMode="Auto"> 
        
                        <telerik:RadGridView.Columns> 
        
                            <telerik:GridViewDataColumn  
        
                                Header="Name"  
        
                                DataMemberBinding="{Binding Name}"> 
        
                            </telerik:GridViewDataColumn> 
        
                            <telerik:GridViewDataColumn  
        
                                Header="Est."  
        
                                DataMemberBinding="{Binding Established}" 
        
                                DataFormatString="{}{0:yyyy}"> 
        
                            </telerik:GridViewDataColumn> 
        
                            <telerik:GridViewDataColumn  
        
                                Header="Stadium Capacity"  
        
                                DataMemberBinding="{Binding StadiumCapacity}" 
        
                                DataFormatString="{}{0:N0}"> 
        
                            </telerik:GridViewDataColumn> 
        
                            <telerik:GridViewDataColumn  
        
                                Header="Ticket Price"  
        
                                DataMemberBinding="{Binding TicketPrice}" 
        
                                DataFormatString="{}{0:C2}"> 
        
                            </telerik:GridViewDataColumn> 
        
                            <telerik:GridViewDataColumn  
        
                                Header="Sellout Revenue"  
        
                                DataMemberBinding="{Binding Path=., Converter={StaticResource clubToSelloutRevenueConverter}}" 
        
                                DataFormatString="{}{0:C2}"> 
        
                            </telerik:GridViewDataColumn> 
        
                        </telerik:RadGridView.Columns> 
        
                    </telerik:RadGridView> 
        
                </Grid> 
        
            </Window>

Each "normal" column is bound to a "normal" property, "{Binding Name}" for example. The calculated column "Sellout Revenue" on the other hand is bound to the whole Club business object: "{Binding Path=., Converter={StaticResource clubToSelloutRevenueConverter}" and lets the converter do the calculation which is the stadium capacity times the ticket price:

    
            using System; 
        
            using System.Globalization; 
        
            using System.Windows.Data; 
        
            namespace TicketID_228472_CalculatedColumns 
        
            { 
        
                internal class ClubToSelloutRevenueConverter : IValueConverter 
        
                { 
        
                    #region IValueConverter Members 
        
                    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) 
        
                    { 
        
                        var club = value as Club; 
        
                        if (club == null) 
        
                        { 
        
                            throw new ArgumentException("value must be a Club", "value"); 
        
                        } 
        
                        return club.StadiumCapacity*club.TicketPrice; 
        
                    } 
        
                    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) 
        
                    { 
        
                        throw new NotImplementedException(); 
        
                    } 
        
                    #endregion 
        
                } 
        
            }

A binding combined with an appropriate converter can let you do virtually anything. Please, see the attached project for the complete source code.

I hope this helps.

Sincerely yours,
Ross
the Telerik team

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answered on 16 Mar 2011, 08:26 PM

Same problem.
I am trying to make reusable duration column, something like this:

public class GridViewDurationColumn : GridViewDataColumn
{
    public DateTime Start
    {
        get { return (DateTime)GetValue(StartProperty); }
        set { SetValue(StartProperty, value); }
    }
 
    public static readonly DependencyProperty StartProperty =
        DependencyProperty.Register("Start", typeof(DateTime), typeof(GridViewDurationColumn), new PropertyMetadata(null));
 
    public DateTime End
    {
        get { return (DateTime)GetValue(EndProperty); }
        set { SetValue(EndProperty, value); }
    }
 
    public static readonly DependencyProperty EndProperty =
        DependencyProperty.Register("End", typeof(DateTime), typeof(GridViewDurationColumn), new PropertyMetadata(null));
 
    public override FrameworkElement CreateCellElement(GridViewCell cell, object dataItem)
    {
        var duration = End - Start;
        return new TextBlock() { Text = duration.ToString() };
    }
 
}
and in Xaml

<local:GridViewDurationColumn Start="{Binding StartDate}" End="{Binding EndDate}" IsReadOnly="True" />
but it doesn't work. Start and End properties are never set.

Converter is a good approach, but if i want to make it reusable i have to pass Start and End to ConverterParameter and then make reflection magic.
i don't think that it is a good idea.

Please help! Thanks