# Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022-2024) # # 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, Sequence, cast from streamlit.elements.form import current_form_id from streamlit.elements.utils import ( check_callback_rules, check_session_state_rules, get_label_visibility_proto_value, maybe_coerce_enum, ) 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, register_widget, ) from streamlit.runtime.state.common import compute_widget_id from streamlit.type_util import ( Key, LabelVisibility, OptionSequence, T, check_python_comparable, ensure_indexable, maybe_raise_label_warnings, to_key, ) from streamlit.util import index_ if TYPE_CHECKING: 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: @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 Markdown and supports the following elements: Bold, Italics, Strikethroughs, Inline Code, Emojis, and Links. This also supports: * Emoji shortcodes, such as ``:+1:`` and ``:sunglasses:``. For a list of all supported codes, see https://share.streamlit.io/streamlit/emoji-shortcodes. * LaTeX expressions, by wrapping them in "$" or "$$" (the "$$" must be on their own lines). Supported LaTeX functions are listed at https://katex.org/docs/supported.html. * Colored text, using the syntax ``:color[text to be colored]``, where ``color`` needs to be replaced with any of the following supported colors: blue, green, orange, red, violet, gray/grey, rainbow. Unsupported 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``. For accessibility reasons, you should never set an empty label (label="") but hide it with label_visibility if needed. In the future, we may disallow empty labels by raising an exception. options : Iterable Labels for the select options in an Iterable. For example, this can be a list, numpy.ndarray, pandas.Series, pandas.DataFrame, or pandas.Index. For pandas.DataFrame, the first column is 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 labels. It receives the option as an argument and its output will be cast to str. 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. Multiple widgets of the same type may not share the same key. help : str An optional tooltip that gets displayed next to the selectbox. 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, which disables the selectbox if set to True. The default is False. label_visibility : "visible", "hidden", or "collapsed" The visibility of the label. If "hidden", the label doesn't show but there is still empty space for it above the widget (equivalent to label=""). If "collapsed", both the label and the space are removed. Default is "visible". 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_callback_rules(self.dg, on_change) check_session_state_rules(default_value=None if index == 0 else index, key=key) maybe_raise_label_warnings(label, label_visibility) opt = ensure_indexable(options) check_python_comparable(opt) id = compute_widget_id( "selectbox", user_key=key, label=label, options=[str(format_func(option)) for option in opt], index=index, key=key, help=help, placeholder=placeholder, form_id=current_form_id(self.dg), page=ctx.page_script_hash if ctx else None, ) 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 between 0 and length of options" ) selectbox_proto = SelectboxProto() selectbox_proto.id = 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", selectbox_proto, user_key=key, on_change_handler=on_change, args=args, kwargs=kwargs, deserializer=serde.deserialize, serializer=serde.serialize, ctx=ctx, ) 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 self.dg._enqueue("selectbox", selectbox_proto) return widget_state.value @property def dg(self) -> "DeltaGenerator": """Get our DeltaGenerator.""" return cast("DeltaGenerator", self)