Tree¶

Added in version 0.6.0

A tree control widget.

Focusable
Container

Example¶

The example below creates a simple tree.

Outputtree.py

from textual.app import App, ComposeResult
from textual.widgets import Tree


class TreeApp(App):
    def compose(self) -> ComposeResult:
        tree: Tree[str] = Tree("Dune")
        tree.root.expand()
        characters = tree.root.add("Characters", expand=True)
        characters.add_leaf("Paul")
        characters.add_leaf("Jessica")
        characters.add_leaf("Chani")
        yield tree


if __name__ == "__main__":
    app = TreeApp()
    app.run()

Tree widgets have a "root" attribute which is an instance of a TreeNode. Call add() or add_leaf() to add new nodes underneath the root. Both these methods return a TreeNode for the child which you can use to add additional levels.

Reactive Attributes¶

Name	Type	Default	Description
`show_root`	`bool`	`True`	Show the root node.
`show_guides`	`bool`	`True`	Show guide lines between levels.
`guide_depth`	`int`	`4`	Amount of indentation between parent and child.

Bindings¶

The tree widget defines the following bindings:

Key(s)	Description
enter	Select the current item.
space	Toggle the expand/collapsed space of the current item.
up	Move the cursor up.
down	Move the cursor down.

Component Classes¶

The tree widget provides the following component classes:

Class	Description
`tree--cursor`	Targets the cursor.
`tree--guides`	Targets the indentation guides.
`tree--guides-hover`	Targets the indentation guides under the cursor.
`tree--guides-selected`	Targets the indentation guides that are selected.
`tree--highlight`	Targets the highlighted items.
`tree--highlight-line`	Targets the lines under the cursor.
`tree--label`	Targets the (text) labels of the items.

Bases: Generic[TreeDataType], ScrollView

A widget for displaying and navigating data in a tree.

Parameters:

Name	Type	Description	Default
`label` ¶	`TextType`	The label of the root node of the tree.	required
`data` ¶	`TreeDataType \| None`	The optional data to associate with the root node of the tree.	`None`
`name` ¶	`str \| None`	The name of the Tree.	`None`
`id` ¶	`str \| None`	The ID of the tree in the DOM.	`None`
`classes` ¶	`str \| None`	The CSS classes of the tree.	`None`
`disabled` ¶	`bool`	Whether the tree is disabled or not.	`False`

BINDINGS `class-attribute` ¶

BINDINGS = [
    Binding(
        "shift+left",
        "cursor_parent",
        "Cursor to parent",
        show=False,
    ),
    Binding(
        "shift+right",
        "cursor_parent_next_sibling",
        "Cursor to next ancestor",
        show=False,
    ),
    Binding(
        "shift+up",
        "cursor_previous_sibling",
        "Cursor to previous sibling",
        show=False,
    ),
    Binding(
        "shift+down",
        "cursor_next_sibling",
        "Cursor to next sibling",
        show=False,
    ),
    Binding("enter", "select_cursor", "Select", show=False),
    Binding("space", "toggle_node", "Toggle", show=False),
    Binding(
        "shift+space",
        "toggle_expand_all",
        "Expand or collapse all",
        show=False,
    ),
    Binding("up", "cursor_up", "Cursor Up", show=False),
    Binding(
        "down", "cursor_down", "Cursor Down", show=False
    ),
]

Key(s)	Description
enter	Select the current item.
space	Toggle the expand/collapsed space of the current item.
up	Move the cursor up.
down	Move the cursor down.

COMPONENT_CLASSES `class-attribute` ¶

COMPONENT_CLASSES = {
    "tree--cursor",
    "tree--guides",
    "tree--guides-hover",
    "tree--guides-selected",
    "tree--highlight",
    "tree--highlight-line",
    "tree--label",
}

Class	Description
`tree--cursor`	Targets the cursor.
`tree--guides`	Targets the indentation guides.
`tree--guides-hover`	Targets the indentation guides under the cursor.
`tree--guides-selected`	Targets the indentation guides that are selected.
`tree--highlight`	Targets the highlighted items.
`tree--highlight-line`	Targets the lines under the cursor.
`tree--label`	Targets the (text) labels of the items.

ICON_NODE `class-attribute` `instance-attribute` ¶

ICON_NODE = '▶ '

Unicode 'icon' to use for an expandable node.

ICON_NODE_EXPANDED `class-attribute` `instance-attribute` ¶

ICON_NODE_EXPANDED = '▼ '

Unicode 'icon' to use for an expanded node.

auto_expand `class-attribute` `instance-attribute` ¶

auto_expand = var(True)

Auto expand tree nodes when they are selected.

center_scroll `class-attribute` `instance-attribute` ¶

center_scroll = var(False)

Keep selected node in the center of the control, where possible.

cursor_line `class-attribute` `instance-attribute` ¶

cursor_line = var(-1, always_update=True)

The line with the cursor, or -1 if no cursor.

cursor_node `property` ¶

cursor_node

The currently selected node, or None if no selection.

guide_depth `class-attribute` `instance-attribute` ¶

guide_depth = reactive(4, init=False)

The indent depth of tree nodes.

hover_line `class-attribute` `instance-attribute` ¶

hover_line = var(-1)

The line number under the mouse pointer, or -1 if not under the mouse pointer.

last_line `property` ¶

last_line

The index of the last line.

root `instance-attribute` ¶

root = _add_node(None, text_label, data)

The root node of the tree.

show_guides `class-attribute` `instance-attribute` ¶

show_guides = reactive(True)

Enable display of tree guide lines.

show_root `class-attribute` `instance-attribute` ¶

show_root = reactive(True)

Show the root of the tree.

NodeCollapsed ¶

NodeCollapsed(node)

Bases: Generic[EventTreeDataType], Message

Event sent when a node is collapsed.

Can be handled using on_tree_node_collapsed in a subclass of Tree or in a parent node in the DOM.

control `property` ¶

control

The tree that sent the message.

node `instance-attribute` ¶

node = node

The node that was collapsed.

NodeExpanded ¶

NodeExpanded(node)

Bases: Generic[EventTreeDataType], Message

Event sent when a node is expanded.

Can be handled using on_tree_node_expanded in a subclass of Tree or in a parent node in the DOM.

control `property` ¶

control

The tree that sent the message.

node `instance-attribute` ¶

node = node

The node that was expanded.

NodeHighlighted ¶

NodeHighlighted(node)

Bases: Generic[EventTreeDataType], Message

Event sent when a node is highlighted.

Can be handled using on_tree_node_highlighted in a subclass of Tree or in a parent node in the DOM.

control `property` ¶

control

The tree that sent the message.

node `instance-attribute` ¶

node = node

The node that was highlighted.

NodeSelected ¶

NodeSelected(node)

Bases: Generic[EventTreeDataType], Message

Event sent when a node is selected.

Can be handled using on_tree_node_selected in a subclass of Tree or in a parent node in the DOM.

control `property` ¶

control

The tree that sent the message.

node `instance-attribute` ¶

node = node

The node that was selected.

action_cursor_down ¶

action_cursor_down()

Move the cursor down one node.

action_cursor_next_sibling ¶

action_cursor_next_sibling()

Move the cursor to the next sibling, or to the paren't sibling if there are no more siblings.

action_cursor_parent ¶

action_cursor_parent()

Move the cursor to the parent node.

action_cursor_parent_next_sibling ¶

action_cursor_parent_next_sibling()

Move the cursor to the parent's next sibling.

action_cursor_previous_sibling ¶

action_cursor_previous_sibling()

Move the cursor to previous sibling, or to the parent if there are no more siblings.

action_cursor_up ¶

action_cursor_up()

Move the cursor up one node.

action_page_down ¶

action_page_down()

Move the cursor down a page's-worth of nodes.

action_page_up ¶

action_page_up()

Move the cursor up a page's-worth of nodes.

action_scroll_end ¶

action_scroll_end()

Move the cursor to the bottom of the tree.

Note

Here bottom means vertically, not branch depth.

action_scroll_home ¶

action_scroll_home()

Move the cursor to the top of the tree.

action_select_cursor ¶

action_select_cursor()

Cause a select event for the target node.

Note

If auto_expand is True use of this action on a non-leaf node will cause both an expand/collapse event to occur, as well as a selected event.

action_toggle_expand_all ¶

action_toggle_expand_all()

Expand or collapse all siblings.

If all the siblings are collapsed then they will be expanded. Otherwise they will all be collapsed.

action_toggle_node ¶

action_toggle_node()

Toggle the expanded state of the target node.

add_json ¶

add_json(json_data, node=None)

Adds JSON data to a node.

Parameters:

Name	Type	Description	Default
`json_data` ¶	`object`	An object decoded from JSON.	required
`node` ¶	`TreeNode \| None`	Node to add data to.	`None`

clear ¶

clear()

Clear all nodes under root.

Returns:

Type	Description
`Self`	The `Tree` instance.

get_label_width ¶

get_label_width(node)

Get the width of the nodes label.

The default behavior is to call render_label and return the cell length. This method may be overridden in a sub-class if it can be done more efficiently.

Parameters:

Name	Type	Description	Default
`node` ¶	`TreeNode[TreeDataType]`	A node.	required

Returns:

Type	Description
`int`	Width in cells.

get_node_at_line ¶

get_node_at_line(line_no)

Get the node for a given line.

Parameters:

Name	Type	Description	Default
`line_no` ¶	`int`	A line number.	required

Returns:

Type	Description
`TreeNode[TreeDataType] \| None`	A tree node, or `None` if there is no node at that line.

get_node_by_id ¶

get_node_by_id(node_id)

Get a tree node by its ID.

Parameters:

Name	Type	Description	Default
`node_id` ¶	`NodeID`	The ID of the node to get.	required

Returns:

Type	Description
`TreeNode[TreeDataType]`	The node associated with that ID.

Raises:

Type	Description
`UnknownNodeID`	Raised if the `TreeNode` ID is unknown.

move_cursor ¶

move_cursor(node, animate=False)

Move the cursor to the given node, or reset cursor.

Parameters:

Name	Type	Description	Default
`node` ¶	`TreeNode[TreeDataType] \| None`	A tree node, or None to reset cursor.	required
`animate` ¶	`bool`	Enable animation	`False`

move_cursor_to_line ¶

move_cursor_to_line(line, animate=False)

Move the cursor to the given line.

Parameters:

Name	Type	Description	Default
`line` ¶	`int`	The line number (negative indexes are offsets from the last line).	required
`animate` ¶		Enable scrolling animation.	`False`

Raises:

Type	Description
`IndexError`	If the line doesn't exist.

process_label ¶

process_label(label)

Process a str or Text value into a label.

May be overridden in a subclass to change how labels are rendered.

Parameters:

Name	Type	Description	Default
`label` ¶	`TextType`	Label.	required

Returns:

Type	Description
`Text`	A Rich Text object.

render_label ¶

render_label(node, base_style, style)

Render a label for the given node. Override this to modify how labels are rendered.

Parameters:

Name	Type	Description	Default
`node` ¶	`TreeNode[TreeDataType]`	A tree node.	required
`base_style` ¶	`Style`	The base style of the widget.	required
`style` ¶	`Style`	The additional style for the label.	required

Returns:

Type	Description
`Text`	A Rich Text object containing the label.

reset ¶

reset(label, data=None)

Clear the tree and reset the root node.

Parameters:

Name	Type	Description	Default
`label` ¶	`TextType`	The label for the root node.	required
`data` ¶	`TreeDataType \| None`	Optional data for the root node.	`None`

Returns:

Type	Description
`Self`	The `Tree` instance.

scroll_to_line ¶

scroll_to_line(line, animate=True)

Scroll to the given line.

Parameters:

Name	Type	Description	Default
`line` ¶	`int`	A line number.	required
`animate` ¶	`bool`	Enable animation.	`True`

scroll_to_node ¶

scroll_to_node(node, animate=True)

Scroll to the given node.

Parameters:

Name	Type	Description	Default
`node` ¶	`TreeNode[TreeDataType]`	Node to scroll in to view.	required
`animate` ¶	`bool`	Animate scrolling.	`True`

select_node ¶

select_node(node)

Move the cursor to the given node and select it, or reset cursor.

Parameters:

Name	Type	Description	Default
`node` ¶	`TreeNode[TreeDataType] \| None`	A tree node to move the cursor to and select, or None to reset cursor.	required

unselect ¶

unselect()

Hide and reset the cursor.

validate_cursor_line ¶

validate_cursor_line(value)

Prevent cursor line from going outside of range.

Parameters:

Name	Type	Description	Default
`value` ¶	`int`	The value to test.	required

Return

A valid version of the given value.

validate_guide_depth ¶

validate_guide_depth(value)

Restrict guide depth to reasonable range.

Parameters:

Name	Type	Description	Default
`value` ¶	`int`	The value to test.	required

Return

A valid version of the given value.

Make non-widget Tree support classes available.

EventTreeDataType `module-attribute` ¶

EventTreeDataType = TypeVar('EventTreeDataType')

The type of the data for a given instance of a Tree.

Similar to TreeDataType but used for Tree messages.

NodeID `module-attribute` ¶

NodeID = NewType('NodeID', int)

The type of an ID applied to a TreeNode.

TreeDataType `module-attribute` ¶

TreeDataType = TypeVar('TreeDataType')

The type of the data for a given instance of a Tree.

AddNodeError ¶

Bases: Exception

Exception raised when there is an error with a request to add a node.

RemoveRootError ¶

Bases: Exception

Exception raised when trying to remove the root of a TreeNode.

TreeNode ¶

TreeNode(
    tree,
    parent,
    id,
    label,
    data=None,
    *,
    expanded=True,
    allow_expand=True
)

Bases: Generic[TreeDataType]

An object that represents a "node" in a tree control.

Parameters:

Name	Type	Description	Default
`tree` ¶	`Tree[TreeDataType]`	The tree that the node is being attached to.	required
`parent` ¶	`TreeNode[TreeDataType] \| None`	The parent node that this node is being attached to.	required
`id` ¶	`NodeID`	The ID of the node.	required
`label` ¶	`Text`	The label for the node.	required
`data` ¶	`TreeDataType \| None`	Optional data to associate with the node.	`None`
`expanded` ¶	`bool`	Should the node be attached in an expanded state?	`True`
`allow_expand` ¶	`bool`	Should the node allow being expanded by the user?	`True`

allow_expand `property` `writable` ¶

allow_expand

Is this node allowed to expand?

children `property` ¶

children

The child nodes of a TreeNode.

data `instance-attribute` ¶

data = data

Optional data associated with the tree node.

id `property` ¶

id

The ID of the node.

is_collapsed `property` ¶

is_collapsed

Is the node collapsed?

is_expanded `property` ¶

is_expanded

Is the node expanded?

is_last `property` ¶

is_last

Is this the last child node of its parent?

is_root `property` ¶

is_root

Is this node the root of the tree?

label `property` `writable` ¶

label

The label for the node.

line `property` ¶

line

The line number for this node, or -1 if it is not displayed.

next_sibling `property` ¶

next_sibling

The next sibling below the node.

parent `property` ¶

parent

The parent of the node.

previous_sibling `property` ¶

previous_sibling

The previous sibling below the node.

siblings `property` ¶

siblings

The siblings of this node (includes self).

tree `property` ¶

tree

The tree that this node is attached to.

add ¶

add(
    label,
    data=None,
    *,
    before=None,
    after=None,
    expand=False,
    allow_expand=True
)

Add a node to the sub-tree.

Parameters:

Name	Type	Description	Default
`label` ¶	`TextType`	The new node's label.	required
`data` ¶	`TreeDataType \| None`	Data associated with the new node.	`None`
`before` ¶	`int \| TreeNode[TreeDataType] \| None`	Optional index or `TreeNode` to add the node before.	`None`
`after` ¶	`int \| TreeNode[TreeDataType] \| None`	Optional index or `TreeNode` to add the node after.	`None`
`expand` ¶	`bool`	Node should be expanded.	`False`
`allow_expand` ¶	`bool`	Allow use to expand the node via keyboard or mouse.	`True`

Returns:

Type	Description
`TreeNode[TreeDataType]`	A new Tree node

Raises:

Type	Description
`AddNodeError`	If there is a problem with the addition request.

Note

Only one of before or after can be provided. If both are provided a AddNodeError will be raised.

add_leaf ¶

add_leaf(label, data=None, *, before=None, after=None)

Add a 'leaf' node (a node that can not expand).

Parameters:

Name	Type	Description	Default
`label` ¶	`TextType`	Label for the node.	required
`data` ¶	`TreeDataType \| None`	Optional data.	`None`
`before` ¶	`int \| TreeNode[TreeDataType] \| None`	Optional index or `TreeNode` to add the node before.	`None`
`after` ¶	`int \| TreeNode[TreeDataType] \| None`	Optional index or `TreeNode` to add the node after.	`None`

Returns:

Type	Description
`TreeNode[TreeDataType]`	New node.

Raises:

Type	Description
`AddNodeError`	If there is a problem with the addition request.

Note

Only one of before or after can be provided. If both are provided a AddNodeError will be raised.

collapse ¶

collapse()

Collapse the node (hide its children).

Returns:

Type	Description
`Self`	The `TreeNode` instance.

collapse_all ¶

collapse_all()

Collapse the node (hide its children) and all those below it.

Returns:

Type	Description
`Self`	The `TreeNode` instance.

expand ¶

expand()

Expand the node (show its children).

Returns:

Type	Description
`Self`	The `TreeNode` instance.

expand_all ¶

expand_all()

Expand the node (show its children) and all those below it.

Returns:

Type	Description
`Self`	The `TreeNode` instance.

refresh ¶

refresh()

Initiate a refresh (repaint) of this node.

remove ¶

remove()

Remove this node from the tree.

Raises:

Type	Description
`RemoveRootError`	If there is an attempt to remove the root.

remove_children ¶

remove_children()

Remove any child nodes of this node.

set_label ¶

set_label(label)

Set a new label for the node.

Parameters:

Name	Type	Description	Default
`label` ¶	`TextType`	A `str` or `Text` object with the new label.	required

toggle ¶

toggle()

Toggle the node's expanded state.

Returns:

Type	Description
`Self`	The `TreeNode` instance.

toggle_all ¶

toggle_all()

Toggle the node's expanded state and make all those below it match.

Returns:

Type	Description
`Self`	The `TreeNode` instance.

UnknownNodeID ¶

Bases: Exception

Exception raised when referring to an unknown TreeNode ID.

Tree¶

Example¶

Reactive Attributes¶

Messages¶

Bindings¶

Component Classes¶

label ¶

data ¶

name ¶

id ¶

classes ¶

disabled ¶

BINDINGS class-attribute ¶

COMPONENT_CLASSES class-attribute ¶

ICON_NODE class-attribute instance-attribute ¶

ICON_NODE_EXPANDED class-attribute instance-attribute ¶

auto_expand class-attribute instance-attribute ¶

center_scroll class-attribute instance-attribute ¶

cursor_line class-attribute instance-attribute ¶

cursor_node property ¶

guide_depth class-attribute instance-attribute ¶

hover_line class-attribute instance-attribute ¶

last_line property ¶

root instance-attribute ¶

show_guides class-attribute instance-attribute ¶

show_root class-attribute instance-attribute ¶

NodeCollapsed ¶

control property ¶

node instance-attribute ¶

NodeExpanded ¶

control property ¶

node instance-attribute ¶

NodeHighlighted ¶

control property ¶

node instance-attribute ¶

NodeSelected ¶

control property ¶

node instance-attribute ¶

action_cursor_down ¶

action_cursor_next_sibling ¶

action_cursor_parent ¶

action_cursor_parent_next_sibling ¶

action_cursor_previous_sibling ¶

action_cursor_up ¶

action_page_down ¶

action_page_up ¶

action_scroll_end ¶

action_scroll_home ¶

action_select_cursor ¶

action_toggle_expand_all ¶

action_toggle_node ¶

add_json ¶

json_data ¶

node ¶

clear ¶

get_label_width ¶

node ¶

get_node_at_line ¶

line_no ¶

get_node_by_id ¶

node_id ¶

move_cursor ¶

node ¶

animate ¶

move_cursor_to_line ¶

line ¶

animate ¶

process_label ¶

label ¶

render_label ¶

node ¶

base_style ¶

style ¶

reset ¶

label ¶

data ¶

scroll_to_line ¶

line ¶

animate ¶

scroll_to_node ¶

`label` ¶

`data` ¶

`name` ¶

`id` ¶

`classes` ¶

`disabled` ¶

BINDINGS `class-attribute` ¶

COMPONENT_CLASSES `class-attribute` ¶

ICON_NODE `class-attribute` `instance-attribute` ¶

ICON_NODE_EXPANDED `class-attribute` `instance-attribute` ¶

auto_expand `class-attribute` `instance-attribute` ¶

center_scroll `class-attribute` `instance-attribute` ¶

cursor_line `class-attribute` `instance-attribute` ¶

cursor_node `property` ¶

guide_depth `class-attribute` `instance-attribute` ¶

hover_line `class-attribute` `instance-attribute` ¶

last_line `property` ¶

root `instance-attribute` ¶

show_guides `class-attribute` `instance-attribute` ¶

show_root `class-attribute` `instance-attribute` ¶

control `property` ¶

node `instance-attribute` ¶

control `property` ¶

node `instance-attribute` ¶

control `property` ¶

node `instance-attribute` ¶

control `property` ¶

node `instance-attribute` ¶

`json_data` ¶

`node` ¶

`node` ¶

`line_no` ¶

`node_id` ¶

`node` ¶

`animate` ¶

`line` ¶

`animate` ¶

`label` ¶

`node` ¶

`base_style` ¶

`style` ¶

`label` ¶

`data` ¶

`line` ¶

`animate` ¶

`node` ¶

`animate` ¶

`node` ¶

`value` ¶

`value` ¶

EventTreeDataType `module-attribute` ¶

NodeID `module-attribute` ¶

TreeDataType `module-attribute` ¶

`tree` ¶

`parent` ¶

`id` ¶

`label` ¶

`data` ¶

`expanded` ¶

`allow_expand` ¶

allow_expand `property` `writable` ¶

children `property` ¶

data `instance-attribute` ¶

id `property` ¶

is_collapsed `property` ¶

is_expanded `property` ¶

is_last `property` ¶

is_root `property` ¶

label `property` `writable` ¶

line `property` ¶

next_sibling `property` ¶

parent `property` ¶

previous_sibling `property` ¶

siblings `property` ¶

tree `property` ¶

`label` ¶

`data` ¶

`before` ¶

`after` ¶

`expand` ¶