[feat] Add Presenter to Session State by sfc-gh-bnisco · Pull Request #12664 · streamlit/streamlit

sfc-gh-bnisco · 2025-09-29T18:18:17Z

Describe your changes

Added a presentation layer for widget values in session state. This allows widgets to define a presenter callable that transforms the stored value into a user-visible form when accessed through st.session_state. The presentation logic is applied when values are retrieved via __getitem__ or through filtered_state.

Key features:

Created a new apply_presenter function that handles the transformation
Integrated presentation into the session state access paths
Ensured presentation is applied exactly once for both direct access and filtered state
Added robust error handling to ensure presentation never interferes with core behavior

GitHub Issue Link (if applicable)

Testing Plan

Unit Tests (Python): Added comprehensive tests in test_presentation.py that verify:
- Base values are returned unchanged when metadata or presenter is missing
- Presenters are correctly applied to transform values
- Exceptions in presenters are properly handled
- Presentation is applied exactly once when accessing values through different paths

Contribution License Agreement

By submitting this pull request you agree that all contributions to this project are made under the Apache 2.0 license.

snyk-io · 2025-09-29T18:18:27Z

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github-actions · 2025-09-29T18:18:32Z

✅ PR preview is ready!

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sfc-gh-bnisco · 2025-09-29T18:18:44Z

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github-actions · 2025-09-29T18:25:19Z

📉 Python coverage change detected

The Python unit test coverage has decreased by 0.0120%

Current PR: 92.8590% (19633 statements, 1402 missed)
Latest develop: 92.8710% (19610 statements, 1398 missed)

✅ Coverage change is within normal range.

Coverage by files

Name	Stmts	Miss	Cover
streamlit/__init__.py	139	0	100%
streamlit/__main__.py	3	3	0%
streamlit/auth_util.py	100	25	75%
streamlit/cli_util.py	39	6	85%
streamlit/column_config.py	3	0	100%
streamlit/commands/__init__.py	0	0	100%
streamlit/commands/echo.py	54	11	80%
streamlit/commands/execution_control.py	59	10	83%
streamlit/commands/experimental_query_params.py	40	2	95%
streamlit/commands/logo.py	41	6	85%
streamlit/commands/navigation.py	106	2	98%
streamlit/commands/page_config.py	101	4	96%
streamlit/components/__init__.py	0	0	100%
streamlit/components/lib/__init__.py	0	0	100%
streamlit/components/lib/local_component_registry.py	35	2	94%
streamlit/components/types/__init__.py	0	0	100%
streamlit/components/types/base_component_registry.py	14	0	100%
streamlit/components/types/base_custom_component.py	49	6	88%
streamlit/components/v1/__init__.py	5	0	100%
streamlit/components/v1/component_arrow.py	33	8	76%
streamlit/components/v1/component_registry.py	41	3	93%
streamlit/components/v1/components.py	4	4	0%
streamlit/components/v1/custom_component.py	85	7	92%
streamlit/components/v2/__init__.py	0	0	100%
streamlit/components/v2/component_definition_resolver.py	30	9	70%
streamlit/components/v2/component_file_watcher.py	117	9	92%
streamlit/components/v2/component_manager.py	96	20	79%
streamlit/components/v2/component_manifest_handler.py	24	0	100%
streamlit/components/v2/component_path_utils.py	68	5	93%
streamlit/components/v2/component_registry.py	118	11	91%
streamlit/components/v2/get_bidi_component_manager.py	8	8	0%
streamlit/components/v2/manifest_scanner.py	224	25	89%
streamlit/config.py	412	12	97%
streamlit/config_option.py	79	3	96%
streamlit/config_util.py	288	7	98%
streamlit/connections/__init__.py	6	0	100%
streamlit/connections/base_connection.py	45	0	100%
streamlit/connections/snowflake_connection.py	60	13	78%
streamlit/connections/snowpark_connection.py	44	3	93%
streamlit/connections/sql_connection.py	56	6	89%
streamlit/connections/util.py	33	0	100%
streamlit/cursor.py	82	2	98%
streamlit/dataframe_util.py	501	45	91%
streamlit/delta_generator.py	204	6	97%
streamlit/delta_generator_singletons.py	76	8	89%
streamlit/deprecation_util.py	59	4	93%
streamlit/development.py	1	0	100%
streamlit/elements/__init__.py	0	0	100%
streamlit/elements/alert.py	60	0	100%
streamlit/elements/arrow.py	198	15	92%
streamlit/elements/balloons.py	10	0	100%
streamlit/elements/bokeh_chart.py	27	0	100%
streamlit/elements/code.py	20	1	95%
streamlit/elements/deck_gl_json_chart.py	104	10	90%
streamlit/elements/dialog_decorator.py	38	0	100%
streamlit/elements/doc_string.py	227	9	96%
streamlit/elements/empty.py	16	4	75%
streamlit/elements/exception.py	101	10	90%
streamlit/elements/form.py	54	2	96%
streamlit/elements/graphviz_chart.py	35	1	97%
streamlit/elements/heading.py	56	0	100%
streamlit/elements/html.py	48	0	100%
streamlit/elements/iframe.py	29	0	100%
streamlit/elements/image.py	32	0	100%
streamlit/elements/json.py	39	2	95%
streamlit/elements/layouts.py	140	3	98%
streamlit/elements/lib/__init__.py	0	0	100%
streamlit/elements/lib/built_in_chart_utils.py	387	26	93%
streamlit/elements/lib/color_util.py	100	4	96%
streamlit/elements/lib/column_config_utils.py	168	1	99%
streamlit/elements/lib/column_types.py	189	4	98%
streamlit/elements/lib/dialog.py	67	1	99%
streamlit/elements/lib/dicttools.py	39	2	95%
streamlit/elements/lib/file_uploader_utils.py	30	0	100%
streamlit/elements/lib/form_utils.py	26	0	100%
streamlit/elements/lib/image_utils.py	176	21	88%
streamlit/elements/lib/js_number.py	28	3	89%
streamlit/elements/lib/layout_utils.py	109	1	99%
streamlit/elements/lib/mutable_status_container.py	73	4	95%
streamlit/elements/lib/options_selector_utils.py	90	0	100%
streamlit/elements/lib/pandas_styler_utils.py	80	2	98%
streamlit/elements/lib/policies.py	56	1	98%
streamlit/elements/lib/streamlit_plotly_theme.py	49	0	100%
streamlit/elements/lib/subtitle_utils.py	76	13	83%
streamlit/elements/lib/utils.py	76	5	93%
streamlit/elements/map.py	110	1	99%
streamlit/elements/markdown.py	63	2	97%
streamlit/elements/media.py	181	8	96%
streamlit/elements/metric.py	91	0	100%
streamlit/elements/pdf.py	49	2	96%
streamlit/elements/plotly_chart.py	114	4	96%
streamlit/elements/progress.py	36	0	100%
streamlit/elements/pyplot.py	39	2	95%
streamlit/elements/snow.py	10	0	100%
streamlit/elements/space.py	12	0	100%
streamlit/elements/spinner.py	34	0	100%
streamlit/elements/text.py	16	0	100%
streamlit/elements/toast.py	26	0	100%
streamlit/elements/vega_charts.py	226	3	99%
streamlit/elements/widgets/__init__.py	0	0	100%
streamlit/elements/widgets/audio_input.py	68	10	85%
streamlit/elements/widgets/button.py	214	3	99%
streamlit/elements/widgets/button_group.py	161	1	99%
streamlit/elements/widgets/camera_input.py	62	10	84%
streamlit/elements/widgets/chat.py	169	40	76%
streamlit/elements/widgets/checkbox.py	52	0	100%
streamlit/elements/widgets/color_picker.py	56	2	96%
streamlit/elements/widgets/data_editor.py	239	14	94%
streamlit/elements/widgets/file_uploader.py	103	18	83%
streamlit/elements/widgets/multiselect.py	105	4	96%
streamlit/elements/widgets/number_input.py	143	5	97%
streamlit/elements/widgets/radio.py	83	5	94%
streamlit/elements/widgets/select_slider.py	97	0	100%
streamlit/elements/widgets/selectbox.py	91	2	98%
streamlit/elements/widgets/slider.py	241	8	97%
streamlit/elements/widgets/text_widgets.py	130	6	95%
streamlit/elements/widgets/time_widgets.py	248	15	94%
streamlit/elements/write.py	166	30	82%
streamlit/emojis.py	4	0	100%
streamlit/env_util.py	21	3	86%
streamlit/error_util.py	33	2	94%
streamlit/errors.py	173	24	86%
streamlit/external/__init__.py	0	0	100%
streamlit/external/langchain/__init__.py	2	0	100%
streamlit/external/langchain/streamlit_callback_handler.py	141	82	42%
streamlit/file_util.py	84	8	90%
streamlit/git_util.py	100	5	95%
streamlit/logger.py	54	0	100%
streamlit/material_icon_names.py	1	0	100%
streamlit/navigation/__init__.py	0	0	100%
streamlit/navigation/page.py	78	2	97%
streamlit/net_util.py	55	3	95%
streamlit/platform.py	10	1	90%
streamlit/runtime/__init__.py	8	0	100%
streamlit/runtime/app_session.py	447	94	79%
streamlit/runtime/caching/__init__.py	19	0	100%
streamlit/runtime/caching/cache_data_api.py	164	3	98%
streamlit/runtime/caching/cache_errors.py	45	4	91%
streamlit/runtime/caching/cache_resource_api.py	122	0	100%
streamlit/runtime/caching/cache_type.py	11	1	91%
streamlit/runtime/caching/cache_utils.py	165	9	95%
streamlit/runtime/caching/cached_message_replay.py	108	1	99%
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streamlit/runtime/caching/legacy_cache_api.py	14	0	100%
streamlit/runtime/caching/storage/__init__.py	2	0	100%
streamlit/runtime/caching/storage/cache_storage_protocol.py	31	2	94%
streamlit/runtime/caching/storage/dummy_cache_storage.py	21	0	100%
streamlit/runtime/caching/storage/in_memory_cache_storage_wrapper.py	60	0	100%
streamlit/runtime/caching/storage/local_disk_cache_storage.py	86	4	95%
streamlit/runtime/connection_factory.py	85	9	89%
streamlit/runtime/context.py	140	0	100%
streamlit/runtime/context_util.py	18	0	100%
streamlit/runtime/credentials.py	139	4	97%
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streamlit/runtime/forward_msg_queue.py	63	4	94%
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streamlit/runtime/media_file_manager.py	69	7	90%
streamlit/runtime/media_file_storage.py	15	0	100%
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streamlit/runtime/memory_uploaded_file_manager.py	41	1	98%
streamlit/runtime/metrics_util.py	190	12	94%
streamlit/runtime/pages_manager.py	59	2	97%
streamlit/runtime/runtime.py	248	18	93%
streamlit/runtime/runtime_util.py	30	1	97%
streamlit/runtime/script_data.py	16	0	100%
streamlit/runtime/scriptrunner/__init__.py	5	0	100%
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streamlit/runtime/scriptrunner/magic.py	83	1	99%
streamlit/runtime/scriptrunner/magic_funcs.py	10	1	90%
streamlit/runtime/scriptrunner/script_cache.py	27	0	100%
streamlit/runtime/scriptrunner/script_runner.py	230	27	88%
streamlit/runtime/scriptrunner_utils/__init__.py	0	0	100%
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streamlit/runtime/scriptrunner_utils/script_requests.py	106	5	95%
streamlit/runtime/scriptrunner_utils/script_run_context.py	135	2	99%
streamlit/runtime/secrets.py	242	26	89%
streamlit/runtime/session_manager.py	60	1	98%
streamlit/runtime/state/__init__.py	7	0	100%
streamlit/runtime/state/common.py	49	2	96%
streamlit/runtime/state/presentation.py	19	4	79%
streamlit/runtime/state/query_params.py	110	3	97%
streamlit/runtime/state/query_params_proxy.py	71	0	100%
streamlit/runtime/state/safe_session_state.py	77	11	86%
streamlit/runtime/state/session_state.py	364	13	96%
streamlit/runtime/state/session_state_proxy.py	62	8	87%
streamlit/runtime/state/widgets.py	12	1	92%
streamlit/runtime/stats.py	42	0	100%
streamlit/runtime/theme_util.py	46	1	98%
streamlit/runtime/uploaded_file_manager.py	39	3	92%
streamlit/runtime/websocket_session_manager.py	66	0	100%
streamlit/source_util.py	36	1	97%
streamlit/string_util.py	88	7	92%
streamlit/temporary_directory.py	18	1	94%
streamlit/testing/__init__.py	0	0	100%
streamlit/testing/v1/__init__.py	2	0	100%
streamlit/testing/v1/app_test.py	239	6	97%
streamlit/testing/v1/element_tree.py	1327	87	93%
streamlit/testing/v1/local_script_runner.py	71	2	97%
streamlit/testing/v1/util.py	17	0	100%
streamlit/time_util.py	28	1	96%
streamlit/type_util.py	138	12	91%
streamlit/url_util.py	39	5	87%
streamlit/user_info.py	87	8	91%
streamlit/util.py	38	1	97%
streamlit/version.py	3	0	100%
streamlit/watcher/__init__.py	3	0	100%
streamlit/watcher/event_based_path_watcher.py	181	24	87%
streamlit/watcher/folder_black_list.py	14	1	93%
streamlit/watcher/local_sources_watcher.py	127	9	93%
streamlit/watcher/path_watcher.py	43	3	93%
streamlit/watcher/polling_path_watcher.py	55	2	96%
streamlit/watcher/util.py	49	1	98%
streamlit/web/__init__.py	0	0	100%
streamlit/web/bootstrap.py	138	18	87%
streamlit/web/cache_storage_manager_config.py	5	0	100%
streamlit/web/cli.py	186	17	91%
streamlit/web/server/__init__.py	5	0	100%
streamlit/web/server/app_static_file_handler.py	29	3	90%
streamlit/web/server/authlib_tornado_integration.py	18	1	94%
streamlit/web/server/bidi_component_request_handler.py	65	8	88%
streamlit/web/server/browser_websocket_handler.py	115	31	73%
streamlit/web/server/component_file_utils.py	24	0	100%
streamlit/web/server/component_request_handler.py	55	4	93%
streamlit/web/server/media_file_handler.py	65	9	86%
streamlit/web/server/oauth_authlib_routes.py	118	18	85%
streamlit/web/server/oidc_mixin.py	44	0	100%
streamlit/web/server/routes.py	90	7	92%
streamlit/web/server/server.py	188	11	94%
streamlit/web/server/server_util.py	67	5	93%
streamlit/web/server/stats_request_handler.py	53	4	92%
streamlit/web/server/upload_file_request_handler.py	53	9	83%
streamlit/web/server/websocket_headers.py	19	1	95%
TOTAL	19633	1402	93%

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github-actions · 2025-09-29T18:26:04Z

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lib/streamlit/runtime/state/presentation.py

sfc-gh-bnisco added the change:feature PR contains new feature or enhancement implementation label Sep 29, 2025 — with Graphite App

sfc-gh-bnisco added the impact:internal PR changes only affect internal code label Sep 29, 2025 — with Graphite App

This was referenced Sep 29, 2025

[feat] Add @streamlit/component-v2-lib package #12626

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[feat] Add protofiles for CCv2 #12627

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[feat] Add ComponentManifest infra #12637

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sfc-gh-bnisco added the security-assessment-completed label Sep 29, 2025 — with Graphite App

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[feat] Add BidiComponentRegistry classes #12646

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[feat] Add ComponentFileWatcher #12647

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[feat] Add ComponentManager and wire it into the Runtime #12660

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[feat] Add BidiComponentRequestHandler and wire it up to the Server #12662

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[feat] Add Presenter to Session State

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[feat] Add Presenter to Session State#12664

[feat] Add Presenter to Session State#12664
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