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Template Column Guide

TemplateColumn<TModel> renders cells through DataTemplate and optional editing template.

Use it when TextColumn/CheckBoxColumn are not enough.

Constructor Options

Choose one of the following constructor families based on how templates are provided.

1. Template Objects

new TemplateColumn<Person>(
    header: "Selected",
    cellTemplate: new FuncDataTemplate<Person>((_, _) => new CheckBox
    {
        [!CheckBox.IsCheckedProperty] = new Binding("IsSelected"),
    }))

2. Template Resource Keys

new TemplateColumn<Person>("Region", "RegionCell", "RegionEditCell")

This resolves templates from control resources at runtime.

XAML Template Example

<TreeDataGrid Source="{Binding Source}">
  <TreeDataGrid.Resources>
    <DataTemplate x:Key="RegionCell">
      <TextBlock Text="{Binding Region}"/>
    </DataTemplate>

    <DataTemplate x:Key="RegionEditCell">
      <ComboBox ItemsSource="{x:Static m:Countries.Regions}"
                SelectedItem="{Binding Region}"/>
    </DataTemplate>
  </TreeDataGrid.Resources>
</TreeDataGrid>

Editing Support

A template column is editable only if editing template is provided.

  • if cellEditingTemplate is null: read-only
  • if provided: editing can start via configured gestures

Options

TemplateColumnOptions<TModel> supports:

  • IsTextSearchEnabled
  • TextSearchValueSelector
  • inherited ColumnOptions<TModel> (sorting, width, edit gestures, etc.)

Example with text search and custom sort:

new TemplateColumn<FileNode>(
    "Name",
    "FileNameCell",
    "FileNameEditCell",
    GridLength.Star,
    new TemplateColumnOptions<FileNode>
    {
        IsTextSearchEnabled = true,
        TextSearchValueSelector = x => x.Name,
        CompareAscending = (a, b) => string.Compare(a?.Name, b?.Name, StringComparison.OrdinalIgnoreCase),
        CompareDescending = (a, b) => string.Compare(b?.Name, a?.Name, StringComparison.OrdinalIgnoreCase),
    })

Runtime Resolution Errors

If resource key is missing, template lookup throws KeyNotFoundException.

Recommendation:

  • keep template keys as constants
  • define templates near the grid using them

Troubleshooting

  • Feature behavior differs from expectations Cause: one or more options in this scenario are configured differently (source type, column options, sort/selection/edit state). Fix: compare your setup with the snippet in this article and verify runtime values on Source, Columns, and Selection.

  • Data changes are not visible in UI Cause: model or collection notifications are missing, or a replaced collection/source is not re-bound. Fix: ensure INotifyPropertyChanged/INotifyCollectionChanged flow is active and reassign Source after replacing underlying collections.

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