601 lines
22 KiB
Python
601 lines
22 KiB
Python
# Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022-2025)
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from __future__ import annotations
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from textwrap import dedent
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from typing import TYPE_CHECKING, Any, Callable, Generic, Literal, cast, overload
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from typing_extensions import Never
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from streamlit.dataframe_util import OptionSequence, convert_anything_to_list
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from streamlit.elements.lib.form_utils import current_form_id
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from streamlit.elements.lib.layout_utils import (
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LayoutConfig,
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WidthWithoutContent,
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validate_width,
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)
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from streamlit.elements.lib.options_selector_utils import (
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create_mappings,
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index_,
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maybe_coerce_enum,
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)
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from streamlit.elements.lib.policies import (
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check_widget_policies,
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maybe_raise_label_warnings,
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)
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from streamlit.elements.lib.utils import (
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Key,
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LabelVisibility,
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compute_and_register_element_id,
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get_label_visibility_proto_value,
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save_for_app_testing,
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to_key,
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)
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from streamlit.errors import StreamlitAPIException
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from streamlit.proto.Selectbox_pb2 import Selectbox as SelectboxProto
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from streamlit.runtime.metrics_util import gather_metrics
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from streamlit.runtime.scriptrunner import ScriptRunContext, get_script_run_ctx
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from streamlit.runtime.state import (
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WidgetArgs,
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WidgetCallback,
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WidgetKwargs,
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get_session_state,
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register_widget,
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)
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from streamlit.type_util import (
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T,
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check_python_comparable,
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)
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if TYPE_CHECKING:
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from collections.abc import Sequence
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from streamlit.delta_generator import DeltaGenerator
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class SelectboxSerde(Generic[T]):
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options: Sequence[T]
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formatted_options: list[str]
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formatted_option_to_option_index: dict[str, int]
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default_option_index: int | None
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def __init__(
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self,
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options: Sequence[T],
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*,
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formatted_options: list[str],
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formatted_option_to_option_index: dict[str, int],
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default_option_index: int | None = None,
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) -> None:
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"""Initialize the SelectboxSerde.
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We do not store an option_to_formatted_option mapping because the generic
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options might not be hashable, which would raise a RuntimeError. So we do
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two lookups: option -> index -> formatted_option[index].
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Parameters
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----------
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options : Sequence[T]
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The sequence of selectable options.
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formatted_options : list[str]
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The string representations of each option. The formatted_options correspond
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to the options sequence by index.
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formatted_option_to_option_index : dict[str, int]
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A mapping from formatted option strings to their corresponding indices in
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the options sequence.
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default_option_index : int or None, optional
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The index of the default option to use when no selection is made.
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If None, no default option is selected.
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"""
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self.options = options
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self.formatted_options = formatted_options
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self.formatted_option_to_option_index = formatted_option_to_option_index
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self.default_option_index = default_option_index
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def serialize(self, v: T | str | None) -> str | None:
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if v is None:
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return None
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if len(self.options) == 0:
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return ""
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# we don't check for isinstance(v, str) because this could lead to wrong
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# results if v is a string that is part of the options itself as it would
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# skip formatting in that case
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try:
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option_index = index_(self.options, v)
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return self.formatted_options[option_index]
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except ValueError:
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# we know that v is a string, otherwise it would have been found in the
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# options
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return cast("str", v)
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def deserialize(self, ui_value: str | None) -> T | str | None:
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# check if the option is pointing to a generic option type T,
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# otherwise return the option itself
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if ui_value is None:
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return (
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self.options[self.default_option_index]
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if self.default_option_index is not None and len(self.options) > 0
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else None
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)
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option_index = self.formatted_option_to_option_index.get(ui_value)
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return self.options[option_index] if option_index is not None else ui_value
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class SelectboxMixin:
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@overload
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def selectbox(
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self,
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label: str,
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options: Sequence[Never], # Type for empty or Never-inferred options
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index: int = 0,
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format_func: Callable[[Any], str] = str,
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key: Key | None = None,
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help: str | None = None,
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on_change: WidgetCallback | None = None,
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args: WidgetArgs | None = None,
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kwargs: WidgetKwargs | None = None,
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*, # keyword-only arguments:
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placeholder: str | None = None,
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disabled: bool = False,
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label_visibility: LabelVisibility = "visible",
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accept_new_options: Literal[False] = False,
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width: WidthWithoutContent = "stretch",
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) -> None: ... # Returns None if options is empty and accept_new_options is False
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@overload
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def selectbox(
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self,
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label: str,
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options: OptionSequence[T],
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index: int = 0,
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format_func: Callable[[Any], str] = str,
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key: Key | None = None,
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help: str | None = None,
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on_change: WidgetCallback | None = None,
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args: WidgetArgs | None = None,
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kwargs: WidgetKwargs | None = None,
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*, # keyword-only arguments:
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placeholder: str | None = None,
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disabled: bool = False,
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label_visibility: LabelVisibility = "visible",
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accept_new_options: Literal[False] = False,
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width: WidthWithoutContent = "stretch",
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) -> T: ...
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@overload
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def selectbox(
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self,
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label: str,
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options: OptionSequence[T],
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index: int = 0,
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format_func: Callable[[Any], str] = str,
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key: Key | None = None,
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help: str | None = None,
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on_change: WidgetCallback | None = None,
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args: WidgetArgs | None = None,
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kwargs: WidgetKwargs | None = None,
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*, # keyword-only arguments:
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placeholder: str | None = None,
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disabled: bool = False,
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label_visibility: LabelVisibility = "visible",
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accept_new_options: Literal[True] = True,
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width: WidthWithoutContent = "stretch",
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) -> T | str: ...
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@overload
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def selectbox(
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self,
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label: str,
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options: OptionSequence[T],
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index: None,
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format_func: Callable[[Any], str] = str,
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key: Key | None = None,
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help: str | None = None,
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on_change: WidgetCallback | None = None,
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args: WidgetArgs | None = None,
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kwargs: WidgetKwargs | None = None,
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*, # keyword-only arguments:
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placeholder: str | None = None,
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disabled: bool = False,
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label_visibility: LabelVisibility = "visible",
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accept_new_options: Literal[False] = False,
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width: WidthWithoutContent = "stretch",
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) -> T | None: ...
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@overload
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def selectbox(
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self,
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label: str,
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options: OptionSequence[T],
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index: None,
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format_func: Callable[[Any], str] = str,
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key: Key | None = None,
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help: str | None = None,
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on_change: WidgetCallback | None = None,
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args: WidgetArgs | None = None,
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kwargs: WidgetKwargs | None = None,
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*, # keyword-only arguments:
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placeholder: str | None = None,
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disabled: bool = False,
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label_visibility: LabelVisibility = "visible",
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accept_new_options: Literal[True] = True,
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width: WidthWithoutContent = "stretch",
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) -> T | str | None: ...
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@overload
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def selectbox(
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self,
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label: str,
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options: OptionSequence[T],
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index: int | None = 0,
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format_func: Callable[[Any], str] = str,
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key: Key | None = None,
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help: str | None = None,
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on_change: WidgetCallback | None = None,
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args: WidgetArgs | None = None,
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kwargs: WidgetKwargs | None = None,
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*, # keyword-only arguments:
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placeholder: str | None = None,
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disabled: bool = False,
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label_visibility: LabelVisibility = "visible",
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accept_new_options: bool = False,
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width: WidthWithoutContent = "stretch",
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) -> T | str | None: ...
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@gather_metrics("selectbox")
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def selectbox(
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self,
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label: str,
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options: OptionSequence[T],
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index: int | None = 0,
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format_func: Callable[[Any], str] = str,
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key: Key | None = None,
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help: str | None = None,
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on_change: WidgetCallback | None = None,
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args: WidgetArgs | None = None,
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kwargs: WidgetKwargs | None = None,
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*, # keyword-only arguments:
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placeholder: str | None = None,
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disabled: bool = False,
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label_visibility: LabelVisibility = "visible",
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accept_new_options: bool = False,
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width: WidthWithoutContent = "stretch",
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) -> T | str | None:
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r"""Display a select widget.
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Parameters
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----------
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label : str
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A short label explaining to the user what this select widget is for.
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The label can optionally contain GitHub-flavored Markdown of the
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following types: Bold, Italics, Strikethroughs, Inline Code, Links,
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and Images. Images display like icons, with a max height equal to
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the font height.
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Unsupported Markdown elements are unwrapped so only their children
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(text contents) render. Display unsupported elements as literal
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characters by backslash-escaping them. E.g.,
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``"1\. Not an ordered list"``.
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See the ``body`` parameter of |st.markdown|_ for additional,
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supported Markdown directives.
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For accessibility reasons, you should never set an empty label, but
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you can hide it with ``label_visibility`` if needed. In the future,
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we may disallow empty labels by raising an exception.
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.. |st.markdown| replace:: ``st.markdown``
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.. _st.markdown: https://docs.streamlit.io/develop/api-reference/text/st.markdown
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options : Iterable
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Labels for the select options in an ``Iterable``. This can be a
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``list``, ``set``, or anything supported by ``st.dataframe``. If
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``options`` is dataframe-like, the first column will be used. Each
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label will be cast to ``str`` internally by default.
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index : int or None
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The index of the preselected option on first render. If ``None``,
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will initialize empty and return ``None`` until the user selects an option.
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Defaults to 0 (the first option).
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format_func : function
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Function to modify the display of the options. It receives
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the raw option as an argument and should output the label to be
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shown for that option. This has no impact on the return value of
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the command.
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key : str or int
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An optional string or integer to use as the unique key for the widget.
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If this is omitted, a key will be generated for the widget
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based on its content. No two widgets may have the same key.
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help : str or None
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A tooltip that gets displayed next to the widget label. Streamlit
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only displays the tooltip when ``label_visibility="visible"``. If
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this is ``None`` (default), no tooltip is displayed.
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The tooltip can optionally contain GitHub-flavored Markdown,
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including the Markdown directives described in the ``body``
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parameter of ``st.markdown``.
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on_change : callable
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An optional callback invoked when this selectbox's value changes.
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args : tuple
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An optional tuple of args to pass to the callback.
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kwargs : dict
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An optional dict of kwargs to pass to the callback.
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placeholder : str or None
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A string to display when no options are selected.
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If this is ``None`` (default), the widget displays placeholder text
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based on the widget's configuration:
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- "Choose an option" is displayed when options are available and
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``accept_new_options=False``.
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- "Choose or add an option" is displayed when options are available
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and ``accept_new_options=True``.
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- "Add an option" is displayed when no options are available and
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``accept_new_options=True``.
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- "No options to select" is displayed when no options are available
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and ``accept_new_options=False``. The widget is also disabled in
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this case.
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disabled : bool
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An optional boolean that disables the selectbox if set to ``True``.
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The default is ``False``.
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label_visibility : "visible", "hidden", or "collapsed"
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The visibility of the label. The default is ``"visible"``. If this
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is ``"hidden"``, Streamlit displays an empty spacer instead of the
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label, which can help keep the widget aligned with other widgets.
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If this is ``"collapsed"``, Streamlit displays no label or spacer.
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accept_new_options : bool
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Whether the user can add a selection that isn't included in ``options``.
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If this is ``False`` (default), the user can only select from the
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items in ``options``. If this is ``True``, the user can enter a new
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item that doesn't exist in ``options``.
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When a user enters a new item, it is returned by the widget as a
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string. The new item is not added to the widget's drop-down menu.
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Streamlit will use a case-insensitive match from ``options`` before
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adding a new item.
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width : "stretch" or int
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The width of the selectbox widget. This can be one of the
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following:
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- ``"stretch"`` (default): The width of the widget matches the
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width of the parent container.
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- An integer specifying the width in pixels: The widget has a
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fixed width. If the specified width is greater than the width of
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the parent container, the width of the widget matches the width
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of the parent container.
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Returns
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-------
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any
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The selected option or ``None`` if no option is selected.
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Examples
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--------
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**Example 1: Use a basic selectbox widget**
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If no index is provided, the first option is selected by default.
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>>> import streamlit as st
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>>>
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>>> option = st.selectbox(
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... "How would you like to be contacted?",
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... ("Email", "Home phone", "Mobile phone"),
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... )
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>>>
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>>> st.write("You selected:", option)
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.. output::
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https://doc-selectbox.streamlit.app/
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height: 320px
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**Example 2: Use a selectbox widget with no initial selection**
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To initialize an empty selectbox, use ``None`` as the index value.
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>>> import streamlit as st
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>>>
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>>> option = st.selectbox(
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... "How would you like to be contacted?",
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... ("Email", "Home phone", "Mobile phone"),
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... index=None,
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... placeholder="Select contact method...",
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... )
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>>>
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>>> st.write("You selected:", option)
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.. output::
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https://doc-selectbox-empty.streamlit.app/
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height: 320px
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**Example 3: Let users add a new option**
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To allow users to add a new option that isn't included in the
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``options`` list, use the ``accept_new_options=True`` parameter. You
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can also customize the placeholder text.
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>>> import streamlit as st
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>>>
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>>> option = st.selectbox(
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... "Default email",
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... ["foo@example.com", "bar@example.com", "baz@example.com"],
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... index=None,
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... placeholder="Select a saved email or enter a new one",
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... accept_new_options=True,
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... )
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>>>
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>>> st.write("You selected:", option)
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.. output::
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https://doc-selectbox-accept-new-options.streamlit.app/
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height: 320px
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"""
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ctx = get_script_run_ctx()
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return self._selectbox(
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label=label,
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options=options,
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index=index,
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format_func=format_func,
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key=key,
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help=help,
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on_change=on_change,
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args=args,
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kwargs=kwargs,
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placeholder=placeholder,
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disabled=disabled,
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label_visibility=label_visibility,
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accept_new_options=accept_new_options,
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width=width,
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ctx=ctx,
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)
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def _selectbox(
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self,
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label: str,
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options: OptionSequence[T],
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index: int | None = 0,
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format_func: Callable[[Any], Any] = str,
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key: Key | None = None,
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help: str | None = None,
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on_change: WidgetCallback | None = None,
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args: WidgetArgs | None = None,
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kwargs: WidgetKwargs | None = None,
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*, # keyword-only arguments:
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placeholder: str | None = None,
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disabled: bool = False,
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label_visibility: LabelVisibility = "visible",
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accept_new_options: bool = False,
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width: WidthWithoutContent = "stretch",
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ctx: ScriptRunContext | None = None,
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) -> T | str | None:
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key = to_key(key)
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check_widget_policies(
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self.dg,
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key,
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on_change,
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default_value=None if index == 0 else index,
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)
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maybe_raise_label_warnings(label, label_visibility)
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opt = convert_anything_to_list(options)
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check_python_comparable(opt)
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if not isinstance(index, int) and index is not None:
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raise StreamlitAPIException(
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f"Selectbox Value has invalid type: {type(index).__name__}"
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)
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if index is not None and len(opt) > 0 and not 0 <= index < len(opt):
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raise StreamlitAPIException(
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"Selectbox index must be greater than or equal to 0 "
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"and less than the length of options."
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)
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# Convert empty string to single space to distinguish from None:
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# - None (default) → "" → Frontend shows contextual placeholders
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# - "" (explicit empty) → " " → Frontend shows empty placeholder
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# - "Custom" → "Custom" → Frontend shows custom placeholder
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if placeholder == "":
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placeholder = " "
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formatted_options, formatted_option_to_option_index = create_mappings(
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|
opt, format_func
|
|
)
|
|
|
|
element_id = compute_and_register_element_id(
|
|
"selectbox",
|
|
user_key=key,
|
|
form_id=current_form_id(self.dg),
|
|
dg=self.dg,
|
|
label=label,
|
|
options=formatted_options,
|
|
index=index,
|
|
help=help,
|
|
placeholder=placeholder,
|
|
accept_new_options=accept_new_options,
|
|
width=width,
|
|
)
|
|
|
|
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[:] = formatted_options
|
|
selectbox_proto.form_id = current_form_id(self.dg)
|
|
selectbox_proto.placeholder = placeholder or ""
|
|
selectbox_proto.disabled = disabled
|
|
selectbox_proto.label_visibility.value = get_label_visibility_proto_value(
|
|
label_visibility
|
|
)
|
|
selectbox_proto.accept_new_options = accept_new_options
|
|
|
|
if help is not None:
|
|
selectbox_proto.help = dedent(help)
|
|
|
|
serde = SelectboxSerde(
|
|
opt,
|
|
formatted_options=formatted_options,
|
|
formatted_option_to_option_index=formatted_option_to_option_index,
|
|
default_option_index=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="string_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.raw_value = serialized_value
|
|
selectbox_proto.set_value = True
|
|
|
|
validate_width(width)
|
|
layout_config = LayoutConfig(width=width)
|
|
|
|
if ctx:
|
|
save_for_app_testing(ctx, element_id, format_func)
|
|
self.dg._enqueue("selectbox", selectbox_proto, layout_config=layout_config)
|
|
return widget_state.value
|
|
|
|
@property
|
|
def dg(self) -> DeltaGenerator:
|
|
"""Get our DeltaGenerator."""
|
|
return cast("DeltaGenerator", self)
|