bootstack.Select#

class bootstack.Select(options=None, *, value=None, signal=None, label=None, message=None, required=False, searchable=False, allow_custom_values=False, group_by=None, max_visible_items=None, read_only=False, disabled=False, width=None, accent=None, density=None, localize=None, parent=None, **kwargs)#

Bases: PublicWidgetBase

A single-selection dropdown field.

The options list is the first positional argument. All options are keyword-only.

Parameters:

  • options (list[Option] | None) – Choices presented in the popup. Each item is a plain string, a (text, value) tuple, or a {'text': ..., 'value': ...} dict — so an option’s displayed label can differ from its stored value. A dict option may also carry 'icon' (a glyph rendered beside the row label) and 'disabled' (when True the row is dimmed and cannot be chosen); any other keys ride along as carried data on selection. Defaults to an empty list.

  • value (Any) – Initially selected value (value-space — matches an option’s value, not its label).

  • signal (Signal[str] | None) – Reactive Signal two-way bound to the field’s displayed text. With decoupled options (text differs from value), bind to the value via on_change/value; the signal carries the display text.

  • label (str | None) – Label displayed above the field.

  • message (str | None) – Hint or helper text displayed below the field.

  • required (bool) – If True, marks the field as required and prevents empty submission.

  • searchable (bool) – If True, typing in the field filters the option list. Defaults to False.

  • allow_custom_values (bool) – If True, users may type values not in options. Defaults to False.

  • group_by (str | None) – Name of an option field to cluster the popup rows under non-selectable group headers (e.g. 'category'). The field is read from each option’s flat record, so it may be any carried bag key (or 'text'/'value'). Groups appear in first-appearance order; an option missing the field renders headerless. Grouping is presentational only — value/selection are unaffected. None (default) renders a flat list.

  • max_visible_items (int | None) – Approximate number of option rows the popup shows before it scrolls (height is max_visible_items * row_height). Group headers and separators consume some of that budget, so the count is approximate. None (default) uses the built-in cap.

  • read_only (bool) – If True, value is visible but the popup cannot be opened.

  • disabled (bool) – If True, field is fully non-interactive and dimmed.

  • width (int | None) – Width in character units.

  • accent (AccentToken | str | None) – Accent token applied to the focus ring.

  • density (WidgetDensity | None) – Padding density.

  • localize (bool | Literal['auto'] | None) – Whether option labels (in the popup and the selected label shown in the field) are translated through the catalog — True, False, or 'auto' (translate when a translation is registered, otherwise show the literal). Defaults to the app’s localize_mode. Set False to keep proper nouns untranslated; override a single option with its localize key. When searching is enabled, search matches the displayed (translated) labels.

  • parent (Any) – Explicit parent widget. If omitted, the current context-stack container is used.

  • **kwargs (Any) – Layout placement options applied by the parent container — fill, expand, anchor, margin, row, column, sticky. See Layout & Spacing.

property disabled: bool#

Whether the field is fully non-interactive.

property group_by: str | None#

Name of the option field the popup clusters rows under, or None.

Assigning a field name groups the popup the next time it opens; assign None to render a flat list. Grouping is presentational only — it does not affect value, selection, or options.

property is_attached: bool#

Whether the widget is currently placed in its layout.

True while the widget occupies space in its parent; False after detach (or before it has ever been placed). A detached widget keeps its state and can be returned to the layout with attach.

property max_visible_items: int | None#

Approximate option-row cap before the popup scrolls, or None.

Assigning takes effect the next time the popup opens; assign None to restore the built-in cap. Height is max_visible_items * row_height, so group headers and separators make the count approximate.

property options: list[OptionDict]#

The available options as normalized {'text', 'value'} records.

Assigning a new list rebuilds the popup. Accepts the same Option forms as the constructor (strings, (text, value) tuples, or dicts).

property read_only: bool#

Whether the field is visible but the popup cannot be opened.

property schedule: Schedule#

Scheduler tied to this widget’s lifetime.

All jobs are automatically cancelled when the widget is destroyed. First access creates the Schedule instance; subsequent accesses return the same instance.

Usage:

self.schedule.delay(500, callback)
self.schedule.every(1000, tick)
job = self.schedule.idle(refresh)
job.cancel()
property selected_index: int#

Zero-based index of the selected option, or -1 if none selected.

property selection: dict | None#

The selected option as a full record dict — the data bag — or None.

{'text': ..., 'value': ..., ...any extra keys}, indexed by key like any record. None when nothing is selected or the value is a custom off-list one. Read-only.

property text: str#

The label currently shown in the field — the selected option’s text.

Read-only; the complement of value (the selection’s value). Assign to value to change the selection.

property value: Any#

The currently selected value, or None if unselected.

This is the option’s value (value-space). For the displayed label, see text.

attach(**kwargs)#

Return a detached widget to its layout, optionally moving it.

With no arguments, restores the widget to exactly where detach took it from. Any layout kwargs accepted by the original placement (e.g. fill, expand, anchor, sticky, margin) override the stored options. For stacked widgets, index= sets the position among the currently attached siblings (or pass an explicit before=/after= sibling); without one, the snapshotted position is used.

Calling attach on a widget that is already attached moves it (the kwargs are re-applied). Fires on_attach.

Parameters:

**kwargs (Any) – Layout placement options to override for this placement.

Raises:

ParentResolutionError – If the widget was never placed in a layout.

destroy()#

Destroy the widget and release the resources it holds.

Removes the widget from its parent, destroys its children, and cancels any pending or repeating jobs on its schedule. After this the widget must not be used again. Destroying a container destroys everything inside it.

detach()#

Remove the widget from its layout without destroying it.

The widget stops occupying space but keeps its state, children, and event bindings, ready to be returned with attach. The current position is snapshotted so a plain attach() restores it exactly — for stacked siblings this is the index among the currently attached siblings, so detaching other siblings first shifts that index.

Calling detach on a widget that is already detached, or one that was never placed in a layout, does nothing. Fires on_detach.

emit(event, *, data=None)#

Fire a named event on this widget, as if it produced the event itself.

This is how a composite widget surfaces high-level activity to its listeners, and the generic counterpart to the on_*() shorthands for firing events that have no dedicated method.

Parameters:

  • event (str) – The event name, unprefixed — the same name you pass to on() or an on_<event>() shorthand (e.g. 'change', 'select').

  • data (Any) – The payload delivered to handlers. For a data-carrying event, pass the matching payload dataclass from bootstack.events — the same object an on_<event>() handler receives. Leave as None for native events (click, hover, focus, …), which carry no payload.

Example

widget.emit("change", data=bs.events.ChangeEvent(value=new_value))
get_clipboard()#

Return the current text contents of the system clipboard.

Returns:

The clipboard text, or an empty string when the clipboard is empty or holds non-text data.

Return type:

str

on(event: str) → Stream#
on(event: str, handler: Callable[[Event], Any]) → Subscription

Register a callback for an event by name.

A generic, string-keyed escape hatch — prefer the typed on_* shorthands (e.g. on_change), which carry the precise payload type. Called with no handler, returns a composable Stream; with a handler, binds it and returns a Subscription.

Parameters:

  • event (str) – Event name (for example 'change' or 'focus').

  • handler (Callable[[Event], Any] | None) – Called with the event payload. Omit to get a composable Stream instead.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_attach(handler=None)#

Register a callback fired when the widget enters the layout.

Fires each time the widget becomes visible in its parent — on initial placement and on every attach. Pair it with on_detach to keep per-visibility resources (timers, observers) tied to the widget’s presence on screen. The handler receives a curated Event.

Parameters:

handler (Callable[[Event], Any] | None) – Called when the widget is attached. Omit to get a composable Stream.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_change() → Stream#
on_change(handler: Callable[[ChangeEvent], Any]) → Subscription

Register a callback fired when the selection changes.

Parameters:

handler (Callable[[ChangeEvent], Any] | None) – Called with a ChangeEvent. Omit to get a composable Stream instead.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_destroy(handler=None)#

Register a callback fired when the widget is destroyed.

Fires once, as the widget is torn down — the place to release resources the widget owns that aren’t cleaned up automatically (file handles, observers, external subscriptions). The handler receives a curated Event.

Parameters:

handler (Callable[[Event], Any] | None) – Called as the widget is destroyed. Omit to get a composable Stream.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

on_detach(handler=None)#

Register a callback fired when the widget leaves the layout.

Fires each time the widget stops occupying space in its parent — on detach and when an ancestor hides it. Pair it with on_attach to release per-visibility resources. The handler receives a curated Event.

Parameters:

handler (Callable[[Event], Any] | None) – Called when the widget is detached. Omit to get a composable Stream.

Returns:

A cancellable Subscription when a handler is given, otherwise a Stream.

Return type:

Stream | Subscription

set_clipboard(text)#

Replace the system clipboard contents with text.

Parameters:

text (str) – The text to place on the clipboard.