Multi Select

Multi select displays selected items as tags inside the input area and presents a filterable dropdown list for multi-selection.

Example

UI Recommendations

Recommendations for creating clear and effective multi selects:

1. The multi select’s text input simplifies searching through large lists. For lists with fewer than 6 items, use a checkbox group.
2. For selecting only one option, use a combo_box instead.
3. Every multi select should have a label specified. Without one, the multi select is ambiguous and not accessible.
4. Options in the multi select should be kept short and concise; multiple lines are strongly discouraged. If more than one line is needed, consider using a description to add context to the option.
5. Choose a width for your multi selects that can accommodate most of the available options.
6. The field labels, menu items, and placeholder text should all be in sentence case.
7. Identify which multi selects are required or optional, and use the is_required field or the necessity_indicator to mark them accordingly.
8. A multi select’s help text should provide actionable guidance on what to select and how to select it, offering additional context without repeating the placeholder text.
9. When an error occurs, the help text specified in a multi select is replaced by error text; thus, ensure both help and error text convey the same essential information to maintain consistent messaging and prevent loss of critical details.
10. Write error messages in a clear, concise, and helpful manner, guiding users to resolve the issue without ambiguity; ideally, they should be 1-2 short, complete sentences.

Data sources

For multi selects, we can use a Deephaven table or URI as a data source to populate the options. When using a table, the first column automatically is used as both the key and the label. If there are any duplicate keys, an error will be thrown; to avoid this, a select_distinct can be used on the table prior to using it as a multi select data source.

Item table sources

If you wish to manually specify the keys and labels, use a ui.item_table_source to dynamically derive the options from a table.

Custom Value

By default, when a multi select loses focus, it resets its input value. To allow users to enter custom values as tags, use the allows_custom_value prop. Pressing Enter when no item is focused adds the typed text as a custom tag. If the typed text matches an existing item’s label, that item’s key is used instead.

HTML Forms

Multi selects can support a name prop for integration with HTML forms, allowing for easy identification of a value on form submission. The form_value prop determines whether comma-joined keys or labels of the selected items are submitted via the hidden form input.

Labeling

Use the label prop to label a multi select. If no label is provided, you must use an aria_label to identify the control for accessibility purposes.

Use the is_required prop and the necessity_indicator props to show whether selecting an option in the multi-select is required or optional.

When the necessity_indicator prop is set to “label”, a localized string for “(required)” or “(optional)” will automatically be generated.

Selection

Use selected_keys or default_selected_keys to set the selected options.

default_selected_keys is useful for simpler scenarios where you don’t need to control the state externally. Use selected_keysfor scenarios where the state should be managed by the parent component, providing control and flexibility over the selection of the multi select.

Sections

Multi selects support sections to group options. Sections can be used by wrapping groups of items in a section element. Each Section takes a title and key prop.

Note that, when searching for options, searching by section will not result in the respective options within that section appearing.

Events

Multi selects support selection via mouse, keyboard, and touch. You can handle all these via the on_change prop. Additionally, multi selects accept an on_input_change prop, which is triggered whenever the search value is edited by the user, whether through typing or option selection.

Each interaction within the multi select will trigger its associated event handler. For instance, typing in the input field triggers the on_input_change, not the on_change.

Complex items

Items within a multi select can include additional content to better convey options. You can add icons, avatars, and descriptions to the children of an ui.item. When adding a description, set the slot prop to “description” to differentiate between the text elements.

Validation

The is_required prop ensures that the user selects an option. The related validation_behaviour prop allows the user to specify aria or native verification.

When the prop is set to “native”, validation errors block form submission and are displayed automatically as help text.

Trigger Options

By default, the multi select’s menu opens when the user types into the input field ("input"). This behavior can be changed to open on focus ("focus") or only when the field button is clicked ("manual") using the menu_trigger prop.

Label position

By default, the label is positioned above the multi select, but it can be moved to the side using the label_position prop.

Quiet State

The is_quiet prop makes a multi select “quiet”. This can be useful when the multi select and its corresponding styling should not distract users from surrounding content.

Disabled State

The is_disabled prop disables a multi select to prevent user interaction. This is useful when the multi select should be visible but unavailable for selection.

Read-only State

The is_read_only prop prevents user input in a multi select, but the selected options should be visible.

Help text

A multi select can have both a description and an error_message. The description remains visible at all times. Use the error message to offer specific guidance on how to correct the input.

Contextual Help

Using the contextual_help prop, a ui.contextual_help can be placed next to the label to provide additional information about the multi select.

Custom width

The width prop adjusts the width of a multi select, and the max_width prop enforces a maximum width.

Align and Direction

The align prop sets the text alignment of the options in the multi select, while the direction prop specifies which direction the menu will open.

API Reference

Children should be one of five types:

Returns: BaseElement The rendered MultiSelect.

Parameters	Type	Default	Description
*children	str | int | float | bool | BaseElement | Element | Table | PartitionedTable | ItemTableSource		The options to render within the multi-select.
menu_trigger	Literal['focus', 'input', 'manual'] | None	'input'	The interaction required to display the menu.
is_quiet	bool | None	None	Whether the component should be displayed with a quiet style.
align	Literal['start', 'end'] | None	'end'	Alignment of the menu relative to the input target.
direction	Literal['bottom', 'top'] | None	'bottom'	Direction the menu will render relative to the component.
loading_state	Literal['loading', 'sorting', 'loadingMore', 'error', 'idle', 'filtering'] | None	None	The current loading state. Determines whether or not the progress circle should be shown.
should_flip	bool	True	Whether the menu should automatically flip direction when space is limited.
menu_width	str | float | None	None	Width of the menu. By default, matches width of the component. Note that the minimum width of the dropdown is always equal to the component's width.
form_value	Literal['key', 'text'] | None	'text'	Whether the text or key of the selected items is submitted as part of an HTML form. Controls whether comma-joined keys or labels are submitted via the hidden form input.
should_focus_wrap	bool | None	None	Whether keyboard navigation is circular.
input_value	str | None	None	The value of the search input (controlled).
default_input_value	str | None	None	The default value of the search input (uncontrolled).
allows_custom_value	bool | None	None	Whether the component allows a non-item matching input value to be set. Pressing Enter when no item is focused adds the typed text as a custom tag. If the typed text matches an existing item's label, that item's key is used instead.
disabled_keys	list[str | int | float | bool] | None	None	The item keys that are disabled. These items cannot be selected, focused, or otherwise interacted with.
selected_keys	Sequence[str | int | float | bool] | None	None	The currently selected keys in the collection (controlled).
default_selected_keys	Sequence[str | int | float | bool] | None	None	The initial selected keys in the collection (uncontrolled).
is_disabled	bool | None	None	Whether the input is disabled.
is_read_only	bool | None	None	Whether the input can be selected but not changed by the user.
is_required	bool | None	None	Whether user input is required on the input before form submission.
validation_behavior	Literal['aria', 'native']	'aria'	Whether to use native HTML form validation to prevent form submission when the value is missing or invalid, or mark the field as required or invalid via ARIA.
auto_focus	bool | None	None	Whether the element should receive focus on render.
label	None | bool | float | int | str | Element | List[NodeType] | Tuple[NodeType, ...]	None	The content to display as the label.
description	Element | None	None	A description for the field. Provides a hint such as specific requirements for what to choose.
error_message	Element | None	None	An error message for the field.
name	str | None	None	The name of the input element, used when submitting an HTML form.
validation_state	Literal['valid', 'invalid'] | None	None	Whether the input should display its "valid" or "invalid" visual styling.
label_position	Literal['top', 'side']	'top'	The label's overall position relative to the element it is labeling.
label_align	Literal['start', 'end'] | None	None	The label's horizontal alignment relative to the element it is labeling.
necessity_indicator	Literal['icon', 'label'] | None	None	Whether the required state should be shown as an icon or text.
contextual_help	Element | None	None	A ContextualHelp element to place next to the label.
key	str | None	None	A unique identifier used by React to render elements in a list.