# Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022-2025) # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. from __future__ import annotations from dataclasses import dataclass from textwrap import dedent from typing import TYPE_CHECKING, Any, Callable, Generic, cast, overload from streamlit.dataframe_util import OptionSequence, convert_anything_to_list from streamlit.elements.lib.form_utils import current_form_id from streamlit.elements.lib.options_selector_utils import index_, maybe_coerce_enum from streamlit.elements.lib.policies import ( check_widget_policies, maybe_raise_label_warnings, ) from streamlit.elements.lib.utils import ( Key, LabelVisibility, compute_and_register_element_id, get_label_visibility_proto_value, save_for_app_testing, to_key, ) from streamlit.errors import StreamlitAPIException from streamlit.proto.Selectbox_pb2 import Selectbox as SelectboxProto from streamlit.runtime.metrics_util import gather_metrics from streamlit.runtime.scriptrunner import ScriptRunContext, get_script_run_ctx from streamlit.runtime.state import ( WidgetArgs, WidgetCallback, WidgetKwargs, get_session_state, register_widget, ) from streamlit.type_util import ( T, check_python_comparable, ) if TYPE_CHECKING: from collections.abc import Sequence from streamlit.delta_generator import DeltaGenerator @dataclass class SelectboxSerde(Generic[T]): options: Sequence[T] index: int | None def serialize(self, v: object) -> int | None: if v is None: return None if len(self.options) == 0: return 0 return index_(self.options, v) def deserialize( self, ui_value: int | None, widget_id: str = "", ) -> T | None: idx = ui_value if ui_value is not None else self.index return self.options[idx] if idx is not None and len(self.options) > 0 else None class SelectboxMixin: @overload def selectbox( self, label: str, options: OptionSequence[T], index: int = 0, format_func: Callable[[Any], Any] = str, key: Key | None = None, help: str | None = None, on_change: WidgetCallback | None = None, args: WidgetArgs | None = None, kwargs: WidgetKwargs | None = None, *, # keyword-only arguments: placeholder: str = "Choose an option", disabled: bool = False, label_visibility: LabelVisibility = "visible", ) -> T: ... @overload def selectbox( self, label: str, options: OptionSequence[T], index: None, format_func: Callable[[Any], Any] = str, key: Key | None = None, help: str | None = None, on_change: WidgetCallback | None = None, args: WidgetArgs | None = None, kwargs: WidgetKwargs | None = None, *, # keyword-only arguments: placeholder: str = "Choose an option", disabled: bool = False, label_visibility: LabelVisibility = "visible", ) -> T | None: ... @gather_metrics("selectbox") def selectbox( self, label: str, options: OptionSequence[T], index: int | None = 0, format_func: Callable[[Any], Any] = str, key: Key | None = None, help: str | None = None, on_change: WidgetCallback | None = None, args: WidgetArgs | None = None, kwargs: WidgetKwargs | None = None, *, # keyword-only arguments: placeholder: str = "Choose an option", disabled: bool = False, label_visibility: LabelVisibility = "visible", ) -> T | None: r"""Display a select widget. Parameters ---------- label : str A short label explaining to the user what this select widget is for. The label can optionally contain GitHub-flavored Markdown of the following types: Bold, Italics, Strikethroughs, Inline Code, Links, and Images. Images display like icons, with a max height equal to the font height. Unsupported Markdown elements are unwrapped so only their children (text contents) render. Display unsupported elements as literal characters by backslash-escaping them. E.g., ``"1\. Not an ordered list"``. See the ``body`` parameter of |st.markdown|_ for additional, supported Markdown directives. For accessibility reasons, you should never set an empty label, but you can hide it with ``label_visibility`` if needed. In the future, we may disallow empty labels by raising an exception. .. |st.markdown| replace:: ``st.markdown`` .. _st.markdown: https://docs.streamlit.io/develop/api-reference/text/st.markdown options : Iterable Labels for the select options in an ``Iterable``. This can be a ``list``, ``set``, or anything supported by ``st.dataframe``. If ``options`` is dataframe-like, the first column will be used. Each label will be cast to ``str`` internally by default. index : int The index of the preselected option on first render. If ``None``, will initialize empty and return ``None`` until the user selects an option. Defaults to 0 (the first option). format_func : function Function to modify the display of the options. It receives the raw option as an argument and should output the label to be shown for that option. This has no impact on the return value of the command. key : str or int An optional string or integer to use as the unique key for the widget. If this is omitted, a key will be generated for the widget based on its content. No two widgets may have the same key. help : str or None A tooltip that gets displayed next to the widget label. Streamlit only displays the tooltip when ``label_visibility="visible"``. If this is ``None`` (default), no tooltip is displayed. The tooltip can optionally contain GitHub-flavored Markdown, including the Markdown directives described in the ``body`` parameter of ``st.markdown``. on_change : callable An optional callback invoked when this selectbox's value changes. args : tuple An optional tuple of args to pass to the callback. kwargs : dict An optional dict of kwargs to pass to the callback. placeholder : str A string to display when no options are selected. Defaults to "Choose an option". disabled : bool An optional boolean that disables the selectbox if set to ``True``. The default is ``False``. label_visibility : "visible", "hidden", or "collapsed" The visibility of the label. The default is ``"visible"``. If this is ``"hidden"``, Streamlit displays an empty spacer instead of the label, which can help keep the widget alligned with other widgets. If this is ``"collapsed"``, Streamlit displays no label or spacer. Returns ------- any The selected option or ``None`` if no option is selected. Example ------- >>> import streamlit as st >>> >>> option = st.selectbox( ... "How would you like to be contacted?", ... ("Email", "Home phone", "Mobile phone"), ... ) >>> >>> st.write("You selected:", option) .. output:: https://doc-selectbox.streamlit.app/ height: 320px To initialize an empty selectbox, use ``None`` as the index value: >>> import streamlit as st >>> >>> option = st.selectbox( ... "How would you like to be contacted?", ... ("Email", "Home phone", "Mobile phone"), ... index=None, ... placeholder="Select contact method...", ... ) >>> >>> st.write("You selected:", option) .. output:: https://doc-selectbox-empty.streamlit.app/ height: 320px """ ctx = get_script_run_ctx() return self._selectbox( label=label, options=options, index=index, format_func=format_func, key=key, help=help, on_change=on_change, args=args, kwargs=kwargs, placeholder=placeholder, disabled=disabled, label_visibility=label_visibility, ctx=ctx, ) def _selectbox( self, label: str, options: OptionSequence[T], index: int | None = 0, format_func: Callable[[Any], Any] = str, key: Key | None = None, help: str | None = None, on_change: WidgetCallback | None = None, args: WidgetArgs | None = None, kwargs: WidgetKwargs | None = None, *, # keyword-only arguments: placeholder: str = "Choose an option", disabled: bool = False, label_visibility: LabelVisibility = "visible", ctx: ScriptRunContext | None = None, ) -> T | None: key = to_key(key) check_widget_policies( self.dg, key, on_change, default_value=None if index == 0 else index, ) maybe_raise_label_warnings(label, label_visibility) opt = convert_anything_to_list(options) check_python_comparable(opt) element_id = compute_and_register_element_id( "selectbox", user_key=key, form_id=current_form_id(self.dg), label=label, options=[str(format_func(option)) for option in opt], index=index, help=help, placeholder=placeholder, ) if not isinstance(index, int) and index is not None: raise StreamlitAPIException( "Selectbox Value has invalid type: %s" % type(index).__name__ ) if index is not None and len(opt) > 0 and not 0 <= index < len(opt): raise StreamlitAPIException( "Selectbox index must be greater than or equal to 0 and less than the length of options." ) session_state = get_session_state().filtered_state if key is not None and key in session_state and session_state[key] is None: index = None selectbox_proto = SelectboxProto() selectbox_proto.id = element_id selectbox_proto.label = label if index is not None: selectbox_proto.default = index selectbox_proto.options[:] = [str(format_func(option)) for option in opt] selectbox_proto.form_id = current_form_id(self.dg) selectbox_proto.placeholder = placeholder selectbox_proto.disabled = disabled selectbox_proto.label_visibility.value = get_label_visibility_proto_value( label_visibility ) if help is not None: selectbox_proto.help = dedent(help) serde = SelectboxSerde(opt, index) widget_state = register_widget( selectbox_proto.id, on_change_handler=on_change, args=args, kwargs=kwargs, deserializer=serde.deserialize, serializer=serde.serialize, ctx=ctx, value_type="int_value", ) widget_state = maybe_coerce_enum(widget_state, options, opt) if widget_state.value_changed: serialized_value = serde.serialize(widget_state.value) if serialized_value is not None: selectbox_proto.value = serialized_value selectbox_proto.set_value = True if ctx: save_for_app_testing(ctx, element_id, format_func) self.dg._enqueue("selectbox", selectbox_proto) return widget_state.value @property def dg(self) -> DeltaGenerator: """Get our DeltaGenerator.""" return cast("DeltaGenerator", self)