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Getting Started with TreeDataGrid

TreeDataGrid is an Avalonia control that combines:

  • DataGrid-style columns
  • Tree-style hierarchical expansion
  • Strongly typed source and column models

Use TreeDataGrid when you need column-based presentation with optional parent/child data and large datasets.

What You Will Build

By the end of Getting Started, you will have:

  • A working TreeDataGrid in XAML
  • A view model exposing a FlatTreeDataGridSource<TModel> or HierarchicalTreeDataGridSource<TModel>
  • Strongly typed columns (TextColumn, TemplateColumn, CheckBoxColumn, HierarchicalExpanderColumn)
  • Working row or cell selection

Learning Path

  1. Installation
  2. Quickstart: Flat TreeDataGrid
  3. Quickstart: Hierarchical TreeDataGrid
  4. Architecture and Data Flow
  5. Columns, Cells, and Rows
  6. Selection Models
  7. TreeDataGrid Glossary

Flat vs Hierarchical

Choose your source type first:

  • FlatTreeDataGridSource<TModel>: table-like data, no children
  • HierarchicalTreeDataGridSource<TModel>: rows may contain nested children

You can still use multiple columns in both modes.

Key Idea

TreeDataGrid separates what to show from how to show it:

  • Source model (ITreeDataGridSource) defines rows, columns, selection, sorting
  • TreeDataGrid control realizes models into visual rows/cells with virtualization

This keeps view models strongly typed and UI behavior predictable.

Next

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.

API Coverage Checklist