bootstack.Form#

class bootstack.Form(*, data=None, items=None, col_count=1, min_col_width=275, on_data_change=None, width=None, height=None, accent=None, buttons=None, parent=None, **kwargs)#

Bases: PublicWidgetBase

Data-entry form built from data or explicit field definitions.

Parameters:

  • data (dict[str, Any] | None) – Initial data dict. Keys become field names; types are inferred when items is not provided.

  • items (Sequence[FormItem | Mapping[str, Any]] | None) – Explicit form layout as FieldItem/GroupItem/TabsItem instances or equivalent dicts.

  • col_count (int) – Number of top-level columns. Default 1.

  • min_col_width (int) – Minimum column width in pixels.

  • on_data_change (Callable[[dict[str, Any]], Any] | None) – Callback invoked with the updated data dict on each field change. Equivalent to calling on_data_change() after construction.

  • width (int | None) – Fixed form width in pixels.

  • height (int | None) – Fixed form height in pixels.

  • accent (AccentToken | str | None) – Accent token for the form container.

  • buttons (Sequence[str | DialogButton | dict[str, Any]] | None) – Footer buttons — strings, DialogButton instances, or dicts.

  • parent (Any) – Override the context-stack parent.

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

property data: dict[str, Any]#

Current form data dict.

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 result: Any#

Value set by button commands. None until a button is pressed.

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 value: dict[str, Any]#

All field values as a dictionary.

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))
field(key)#

Return the Field widget for the given key.

field_signal(key)#

Return the Signal for the named field value.

field_textsignal(key)#

Return the text Signal for the named field.

fields()#

Return all field widgets in insertion order.

get()#

Return all field values as a dictionary.

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

get_field_value(key)#

Return the current value of the named field.

keys()#

Return all field keys in insertion order.

on(event, handler=None)#

Bind handler to event, or return a composable Stream.

With a handler — binds immediately and returns a Subscription:

sub = widget.on("change", handler)
sub.cancel()

Without a handler — returns a Stream for operator chaining. The Tk binding is created lazily when .listen() is called:

sub = widget.on("change").debounce(300).listen(handler)
sub.cancel()
Parameters:

  • event (str) – Event name (e.g. "change", "click").

  • handler (Callable[[Any], Any] | None) – Optional callback. If omitted, a Stream is returned.

Returns:

Subscription when a handler is provided; Stream otherwise.

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_data_change() → Stream#
on_data_change(handler: Callable[[dict[str, Any]], Any]) → Subscription

Register a callback fired whenever any field value changes.

The handler receives the current form data as a dict. Called with no handler, returns a composable Stream.

Parameters:

handler (Callable[[dict[str, Any]], Any] | None) – Called with the updated data dict on each field change.

Returns:

Subscription (with handler) or Stream (without handler).

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(values)#

Set multiple field values from a dictionary.

set_clipboard(text)#

Replace the system clipboard contents with text.

Parameters:

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

set_field_value(key, value)#

Set the value of the named field.

validate()#

Run validation rules; returns True if all fields pass.