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c#mvvmdatagridprismselectionchanged
StuC
StuC

Reputation: 71

DataGrid Combobox SelectionChanged Event firing on scroll

I am having trouble with the SelectionChanged event trigger for a combobox on my data grid.

The combobox items source is bound to my view model. The combobox selected item is also bound to my view model.

When I change the combobox selected item, a delegate command on the view model is fired which goes off and updates etc. But when I scroll the data grid the SelectionChanged event also fires.

I am also using Prism MVVM.

Here is my XAML:

<DataGrid.Columns>
  <DataGridTemplateColumn Header="Selected Reason" Width="150">
    <DataGridTemplateColumn.CellTemplate>
      <DataTemplate>
        <ComboBox ItemsSource="{Binding Path=DataContext.Reasons, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}}"
            SelectedItem="{Binding SelectedReason}">
          <i:Interaction.Triggers>
            <i:EventTrigger EventName="SelectionChanged">
              <i:InvokeCommandAction Command="{Binding Path=DataContext.ReasonChangedCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}}" 
                    CommandParameter="{Binding}"/>
              </i:EventTrigger>
            </i:Interaction.Triggers>
        </ComboBox>
      </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
  </DataGridTemplateColumn>
</DataGrid.Columns>

Here is my View Model command:

private DelegateCommand<T> _reasonChangedCommand;
public DelegateCommand<T> ReasonChangedCommand =>
            _reasonChangedCommand ?? (_reasonChangedCommand = new DelegateCommand<T>(ReasonChanged));

    private async void ReasonChanged(T obj)
    {
         if (obj != null)
         {       
             await _updateRepository.UpdateAsync(obj);          
         }
    }

All articles I have searched discuss the command not firing and not firing when the data grid is scrolled. Any help or direction to an article would be much appreciated.

Many Thanks.

Upvotes: 3

Views: 1300

Answers (1)

StuC
StuC

Reputation: 71

After playing around with different event triggers, using DropDownClosed event resolves this issue.

Upvotes: 4

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