CODEWITHSUNDEEP
c#wpfdata-bindingdatagrid
Søren Lorentzen
Søren Lorentzen

Reputation: 866

Disabling button in bottom row in a wpf datagrid

I have a DataGrid with 4 columns, the first two of them are bound to an object. The other two are button columns are made like this

<DataGridTemplateColumn  MaxWidth="100" Header="Delete">
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <Button Name="BtnDelete" CommandParameter="{Binding Path=Id}" Content="Delete" Click="BtnDeleteEmployee_Click" />
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>

My Datagrid has CanUserAddRows="True" which always generates an empty row in the bottom of the grid. However, I would like the two buttons on the bottom row to be disabled until the other rows have been filled. As it is now, I'm (of course) getting a nullreferenceexception when I click the button.

I guess a solution would be to bind the button's IsEnabled property to 

id>0

But how to do this, I am not sure.

Upvotes: 1

Views: 3170

Answers (3)

Greatran
Greatran

Reputation: 190

You can use style Trigger as below 

 <Button.Style>
     <Style TargetType="{x:Type Button}">
         <Setter Property="Visibility" Value="Visible"/>
         <Style.Triggers>
              <DataTrigger Binding="{Binding Id}" Value="{x:Null}">
                   <Setter Property="Visibility" Value="Hidden"/>
              </DataTrigger>
         </Style.Triggers>
     </Style>
</Button.Style>

This example hide the button completly when the value of Id is null. But same can be done with IsEnabled property to disable the button

Upvotes: 2

Magnus Johansson
Magnus Johansson

Reputation: 28325

One way to accomplish this is to bind the IsEnabled property to the Id property and use a ValueConverter to retun True or False based on your criteria.

A value converter could look like this:

public class IdToEnabledConverter:IValueConverter
{
  public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
  {
    return value != null && (int)value > 0;
  }

  public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
  {
    throw new NotImplementedException();
  }
}

and you reference it in your resources section:

<Grid.Resources>
  <local:IdToEnabledConverter x:Key="IdToEnabledConverter"/>
</Grid.Resources>

And bind the IsEnabled property:

<Button IsEnabled="{Binding Id, Converter={StaticResource IdToEnabledConverter}}"/>

Upvotes: 1

Augustinas Nomicas
Augustinas Nomicas

Reputation: 46

I suggest using MVVM pattern and Commands. If you use commands with button, it will automatically be disabled based on CanExecute() return value. So this is a place where you could check if id>0.

Some useful info about commands: http://relentlessdevelopment.wordpress.com/2010/03/30/simplified-mvvm-commanding-with-delegatecommand/

Upvotes: 1

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