Interface

# HierarchicalTableDataSource

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Hierarchical Table Data Source

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## Description

Lets a `TableDataSource</api/interfaces/tabledatasource>` supply expandable rows.

Implement it in addition to `TableDataSource</api/interfaces/tabledatasource>` to report which rows can be expanded, how deep each row sits in the hierarchy and what happens when the user opens or closes a row. The source stays responsible for the row count: after expanding or collapsing, it reports the rows that are visible now.

## Methods

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| Name                                                               | Parameters                                | Returns                            | Shared |
|--------------------------------------------------------------------|-------------------------------------------|------------------------------------|--------|
| `CollapseRowAt<hierarchicaltabledatasource.collapserowat>`         | row As `Integer</api/data_types/integer>` |                                    |        |
| `ExpandRowAt<hierarchicaltabledatasource.expandrowat>`             | row As `Integer</api/data_types/integer>` |                                    |        |
| `RowDepthAt<hierarchicaltabledatasource.rowdepthat>`               | row As `Integer</api/data_types/integer>` | `Integer</api/data_types/integer>` |        |
| `RowIsExpandableAt<hierarchicaltabledatasource.rowisexpandableat>` | row As `Integer</api/data_types/integer>` | `Boolean</api/data_types/boolean>` |        |
| `RowIsExpandedAt<hierarchicaltabledatasource.rowisexpandedat>`     | row As `Integer</api/data_types/integer>` | `Boolean</api/data_types/boolean>` |        |

## Method descriptions

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HierarchicalTableDataSource.CollapseRowAt

**CollapseRowAt**(row As `Integer</api/data_types/integer>`)

> Remove the *row*'s children from the visible projection. Afterwards the source reports only the rows that are visible now, so the row count shrinks by the children that were removed.
>
> This example removes every following row that sits deeper:
>
> ``` xojo
> ' Remove every following row that sits deeper than this one
> Var depth As Integer = mRows(row).Depth
>
> While row + 1 <= mRows.LastIndex And mRows(row + 1).Depth > depth
>   mRows.RemoveAt(row + 1)
> Wend
>
> mRows(row).Expanded = False
> ```

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HierarchicalTableDataSource.ExpandRowAt

**ExpandRowAt**(row As `Integer</api/data_types/integer>`)

> Insert the *row*'s children directly after `row`. The children become rows of their own, so the row count grows and the rows below move down.
>
> This example inserts the children directly below their parent:
>
> ``` xojo
> ' The children become rows of their own, directly below their parent
> Var children() As Record = ChildrenOf(mRows(row))
>
> For i As Integer = children.LastIndex DownTo 0
>   mRows.AddAt(row + 1, children(i))
> Next
>
> mRows(row).Expanded = True
> ```

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HierarchicalTableDataSource.RowDepthAt

**RowDepthAt**(row As `Integer</api/data_types/integer>`) As `Integer</api/data_types/integer>`

> Indentation depth, `0` = top level. It is what the table indents by, so a child sits one level deeper than its parent.
>
> This example reports the depth the record sits at:
>
> ``` xojo
> Return mRows(row).Depth
> ```

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HierarchicalTableDataSource.RowIsExpandableAt

**RowIsExpandableAt**(row As `Integer</api/data_types/integer>`) As `Boolean</api/data_types/boolean>`

> Whether the *row* shows a disclosure widget. Only a row that says `True</api/language/true>` here can be opened by the user.
>
> This example reports whether the record has children:
>
> ``` xojo
> Return mRows(row).HasChildren
> ```

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HierarchicalTableDataSource.RowIsExpandedAt

**RowIsExpandedAt**(row As `Integer</api/data_types/integer>`) As `Boolean</api/data_types/boolean>`

> Whether the *row* is currently expanded. The table asks while drawing, so the widget always matches what the source reports.
>
> This example reports the state the record carries:
>
> ``` xojo
> Return mRows(row).Expanded
> ```

## Compatibility

|                       |         |
|-----------------------|---------|
| **Project Types**     | Desktop |
| **Operating Systems** | All     |

<div class="seealso">

`DesktopTable</api/user_interface/desktop/desktoptable>`, `TableDataSource</api/interfaces/tabledatasource>`, `EditableTableDataSource</api/interfaces/editabletabledatasource>`, `SortableTableDataSource</api/interfaces/sortabletabledatasource>`

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