WPF Toolkit DataGrid Supporting Multiple Column Sets

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Introduction

The WPF Toolkit's DataGrid is a powerful grid control allowing to format data in various ways.

In my application, I wanted the user to be able to control which data he gets displayed in the DataGrid. To do so, he can open an options dialog and choose between some radio buttons. Each radio button defines a set of data columns displayed in the DataGrid.

While it is possible to define multiple column sets by code (DataGrid.Columns property), the DataGrid only allows to define one column set via XAML.

The MultiColSetDataGrid control described in this article helps to overcome this limitation.

Background

The class MultiColSetDataGrid has a property ColumnsDefinitionList containing a list of column sets and a property RowDetailsTemplateList containing a list of DataTemples displayed in the row details area.

A further property GridColumnsDefinitionsIndex controls which column set and row details DataTemplate is currently set. This property can be databinded by view models.

Using the Code

The MainWindow.xaml file contains the MultiColumnSetDataGrid control:

<ctrl:MultiColSetDataGrid x:Name="myGrid" 
    ItemsSource="{Binding PersonList}" 
    .... 

The MainWindowVM's (view model) property PersonList is used as ItemsSource. The list is a list of persons. Each entry is of type PersonVM offering FirstName and LastName as String properties.

<ctrl:MultiColSetDataGrid.ColumnsDefinitionList>
  <ctrl:ColumnsDefinition>
    <ctrl:ColumnsDefinition.GridColumns>
      <tk:DataGridTextColumn Width="Auto" 
        Header="First Name" 
        Binding="{Binding FirstName}" />
    </ctrl:ColumnsDefinition.GridColumns>
  </ctrl:ColumnsDefinition>
  <ctrl:ColumnsDefinition>
    <ctrl:ColumnsDefinition.GridColumns>
      <tk:DataGridTextColumn Width="Auto" 
        Header="First Name" 
        Binding="{Binding FirstName}" />
      <tk:DataGridTextColumn Width="Auto" 
        Header="Last Name" 
        Binding="{Binding LastName}" />
    </ctrl:ColumnsDefinition.GridColumns>
  </ctrl:ColumnsDefinition>
</ctrl:MultiColSetDataGrid.ColumnsDefinitionList>        

Two DataTemplates are defined for the row details section:

<ctrl:MultiColSetDataGrid.RowDetailsTemplateList>
  <DataTemplate>
    <StackPanel Orientation="Horizontal" Margin="20,0,0,0">
      <TextBlock Text="Name: " FontWeight="Bold"/>
      <TextBlock Text="{Binding FirstName}"/>
    </StackPanel>
  </DataTemplate>
  <DataTemplate>
    <StackPanel Orientation="Horizontal" Margin="20,0,0,0">
      <TextBlock Text="Name: " FontWeight="Bold"/>
      <TextBlock Text="{Binding LastName}"/>
      <TextBlock Text=", "/>
      <TextBlock Text="{Binding FirstName}"/>
    </StackPanel>
  </DataTemplate>
</ctrl:MultiColSetDataGrid.RowDetailsTemplateList>

A button is used to switch between the column sets:

<Button Width="120" Command="{Binding CmdSwitch}" Content="Switch Column Sets" /> 

The MainWindowVM has an integer property CurrentColumnSetIndex, which determines the column set currently used. This property is binded to the MultiColumnSetDataGrid's dependency property GridColumnsDefinitionsIndex.

<ctrl:MultiColSetDataGrid x:Name="myGrid" 
    ...
    GridColumnsDefinitionsIndex="{Binding CurrentColumnSetIndex, Mode=TwoWay}"> 

The ViewModel's ICommand bound to the button switches the CurrentColumnSetIndex value from 0 to 1 and vice versa.

public ICommand CmdSwitch
{
  get
  {
    return new RelayCommand(p => DoSwitch());
  }
}

private void DoSwitch()
{
  if (this.CurrentColumnSetIndex == 0)
    this.CurrentColumnSetIndex = 1;
  else
    this.CurrentColumnSetIndex = 0;
} 

The setter of MultiColSetDataGrid's property GridColumnsDefinitionsIndex is called via databinding and calls method LoadColumns...

public Int32 GridColumnsDefinitionsIndex
{
  get
  {
    return (Int32)this.GetValue(GridColumnsDefinitionsIndexProperty);
  }
  set
  {
    this.SetValue(GridColumnsDefinitionsIndexProperty, value);
    LoadColumns();
  }
}

And in method LoadColumns the defined column set behind the index is loaded:

private void LoadColumns()
{
  int tmpIndex = this.GridColumnsDefinitionsIndex;
  if (this.ColumnsDefinitionList == null || tmpIndex < 0 || 
		tmpIndex >= this.ColumnsDefinitionList.Count)
    return;

  // Load column set
  List<DataGridColumn> tmpColumns = 
		this.ColumnsDefinitionList[tmpIndex].GridColumns;
  this.Columns.Clear();
  foreach (var tmpColumn in tmpColumns)
    this.Columns.Add(tmpColumn);

  // Set RowDetailsTemplate
  if (this.RowDetailsTemplateList == null || tmpIndex < 0 || 
		tmpIndex >= this.RowDetailsTemplateList.Count)
    return;
  this.RowDetailsTemplate = this.RowDetailsTemplateList[tmpIndex];
}

The following screenshot shows the application after startup containing the column set with index 0 displaying the "First Name" column only:

The following screenshot shows the application after having clicked on the "Switch column sets" button. The grid is displaying the"First Name" and "Last Name" columns:

History

• Initial version