Dropdown

class marimo.ui.dropdown(options: Sequence[str] | dict[str, Any], value: str | None = None, allow_select_none: bool | None = None, *, label: str = '', on_change: Callable[[Any], None] | None = None)

A dropdown menu.

Example.

dropdown = mo.ui.dropdown(
  options=['a', 'b', 'c'],
  value='a',
  label='choose one'
)

dropdown = mo.ui.dropdown(
  options={'one': 1, 'two': 2, 'three': 3},
  value='one',
  label='pick a number'
)

Attributes.

• value: the selected value, or None if no selection

• options: a dict mapping option name to option value

Initialization Args.

• options: sequence of text options, or dict mapping option name to option value

• value: default option name

• allow_select_none: whether to include special option ("--") for a None value; when None, defaults to True when value is None

• label: text label for the element

• on_change: optional callback to run when this element’s value changes

Public methods

Inherited from UIElement

form([label])

Create a submittable form out of this UIElement.

Inherited from Html

batch(**elements)	Convert an HTML object with templated text into a UI element.
center()	Center an item.
right()	Right-justify.
left()	Left-justify.
callout([kind])	Create a callout containing this HTML element.

Public Data Attributes:

selected_key

The selected option’s key, or None if no selection.

Inherited from UIElement

value

The element’s current value.

Inherited from Html

text	A string of HTML representing this element.

---

property selected_key: str | None

The selected option’s key, or None if no selection.