[Prototype] Add key parameter to st.container

frontend/lib/src/components/core/Block/Block.tsx

@@ -334,7 +334,15 @@ const VerticalBlock = (props: BlockPropsWithoutWidth): ReactElement => {
       data-test-scroll-behavior="normal"
     >
       <StyledVerticalBlockWrapper ref={wrapperElement}>
-        <StyledVerticalBlock width={width} data-testid="stVerticalBlock">
+        <StyledVerticalBlock
+          width={width}
+          data-testid="stVerticalBlock"
+          className={
+            props.node.deltaBlock.key
+              ? `st-${props.node.deltaBlock.key}`
+              : undefined
+          }
+        >
           <ChildRenderer {...propsWithNewWidth} />
         </StyledVerticalBlock>
       </StyledVerticalBlockWrapper>

lib/streamlit/components/v1/custom_component.py

@@ -20,7 +20,7 @@
 from streamlit import _main, type_util
 from streamlit.components.types.base_custom_component import BaseCustomComponent
 from streamlit.elements.form import current_form_id
-from streamlit.elements.utils import check_cache_replay_rules
+from streamlit.elements.utils import check_cache_replay_rules, current_container_key
 from streamlit.errors import StreamlitAPIException
 from streamlit.proto.Components_pb2 import ArrowTable as ArrowTableProto
 from streamlit.proto.Components_pb2 import SpecialArg
@@ -169,6 +169,7 @@ def marshall_element_args():
                     key=key,
                     json_args=serialized_json_args,
                     special_args=special_args,
+                    container_key=current_container_key(dg),
                     page=ctx.page_script_hash if ctx else None,
                 )
             else:
@@ -179,6 +180,7 @@ def marshall_element_args():
                     form_id=current_form_id(dg),
                     url=self.url,
                     key=key,
+                    container_key=current_container_key(dg),
                     page=ctx.page_script_hash if ctx else None,
                 )
             element.component_instance.id = computed_id

lib/streamlit/delta_generator.py

@@ -277,6 +277,7 @@ def __init__(
 
         # If this an `st.form` block, this will get filled in.
         self._form_data: FormData | None = None
+        self._container_key: str | None = None
 
         # Change the module of all mixin'ed functions to be st.delta_generator,
         # instead of the original module (e.g. st.elements.markdown)

lib/streamlit/elements/layouts.py

@@ -14,13 +14,15 @@
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Literal, Sequence, Union, cast
+import re
+from typing import TYPE_CHECKING, Final, Literal, Sequence, Union, cast
 
 from typing_extensions import TypeAlias
 
 from streamlit.errors import StreamlitAPIException
 from streamlit.proto.Block_pb2 import Block as BlockProto
 from streamlit.runtime.metrics_util import gather_metrics
+from streamlit.type_util import Key, to_key
 
 if TYPE_CHECKING:
     from streamlit.delta_generator import DeltaGenerator
@@ -29,11 +31,18 @@
 
 SpecType: TypeAlias = Union[int, Sequence[Union[int, float]]]
 
+# Pattern to validate a container key (to be compatible with css class names):
+_KEY_PATTERN: Final = re.compile(r"^[a-zA-Z_][a-zA-Z0-9\-_]*$")
+
 
 class LayoutsMixin:
     @gather_metrics("container")
     def container(
-        self, *, height: int | None = None, border: bool | None = None
+        self,
+        *,
+        height: int | None = None,
+        border: bool | None = None,
+        key: Key | None = None,
     ) -> DeltaGenerator:
         """Insert a multi-element container.
 
@@ -130,6 +139,15 @@ def container(
         block_proto = BlockProto()
         block_proto.allow_empty = False
         block_proto.vertical.border = border or False
+        if key := to_key(key):
+            if not _KEY_PATTERN.match(key):
+                raise StreamlitAPIException(
+                    f"Invalid key '{key}'. Key must match the pattern '{_KEY_PATTERN.pattern}'."
+                )
+            block_proto.key = key
+            # Set the container key in the DeltaGenerator
+            self.dg._container_key = key
+
         if height:
             # Activate scrolling container behavior:
             block_proto.allow_empty = True

lib/streamlit/elements/utils.py

@@ -86,6 +86,35 @@
         _shown_default_value_warning = True
 
 
+def current_container_key(this_dg: DeltaGenerator) -> str | None:
+    """Find the container key for the given DeltaGenerator."""
+    # Avoid circular imports.
+    from streamlit.delta_generator import dg_stack
+
+    if not runtime.exists():
+        return None
+
+    if this_dg._container_key is not None:
+        return this_dg._container_key
+
+    if this_dg == this_dg._main_dg:
+        # We were created via an `st.foo` call.
+        # Walk up the dg_stack to see if there is a container key set.
+        for dg in reversed(dg_stack.get()):
+            if dg._container_key is not None:
+                return dg._container_key
+    else:
+        # We were created via an `dg.foo` call.
+        # Take a look at our parent's container key.
+        parent = this_dg._parent
+        if parent is not None and parent._container_key is not None:
+            return parent._container_key
+        else:
+            return current_container_key(parent)
+
+    return None
+
+
 class CachedWidgetWarning(StreamlitAPIWarning):
     def __init__(self):
         super().__init__(

lib/streamlit/elements/widgets/button.py

@@ -560,6 +560,7 @@ def _download_button(
             check_cache_replay_rules,
             check_callback_rules,
             check_session_state_rules,
+            current_container_key,
         )
 
         check_cache_replay_rules()
@@ -576,6 +577,7 @@ def _download_button(
             help=help,
             type=type,
             use_container_width=use_container_width,
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 
@@ -724,6 +726,7 @@ def _button(
             check_cache_replay_rules,
             check_callback_rules,
             check_session_state_rules,
+            current_container_key,
         )
 
         if not is_form_submitter:
@@ -740,6 +743,7 @@ def _button(
             is_form_submitter=is_form_submitter,
             type=type,
             use_container_width=use_container_width,
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 

lib/streamlit/elements/widgets/camera_input.py

@@ -25,6 +25,7 @@
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
+    current_container_key,
     get_label_visibility_proto_value,
 )
 from streamlit.elements.widgets.file_uploader import _get_upload_files
@@ -210,6 +211,7 @@ def _camera_input(
             key=key,
             help=help,
             form_id=current_form_id(self.dg),
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 

lib/streamlit/elements/widgets/chat.py

@@ -298,6 +298,7 @@ def chat_input(
             check_cache_replay_rules,
             check_callback_rules,
             check_session_state_rules,
+            current_container_key,
         )
 
         check_cache_replay_rules()
@@ -311,6 +312,7 @@ def chat_input(
             key=key,
             placeholder=placeholder,
             max_chars=max_chars,
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 

lib/streamlit/elements/widgets/checkbox.py

@@ -34,7 +34,7 @@
     WidgetKwargs,
     register_widget,
 )
-from streamlit.runtime.state.common import compute_widget_id
+from streamlit.runtime.state.common import compute_widget_id, current_container_key
 from streamlit.type_util import Key, LabelVisibility, maybe_raise_label_warnings, to_key
 
 if TYPE_CHECKING:
@@ -293,6 +293,7 @@ def _checkbox(
             key=key,
             help=help,
             form_id=current_form_id(self.dg),
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 

lib/streamlit/elements/widgets/color_picker.py

@@ -20,7 +20,7 @@
 from typing import cast
 
 import streamlit
-from streamlit.elements.form import current_form_id
+from streamlit.elements.form import current_container_key, current_form_id
 from streamlit.elements.utils import (
     check_cache_replay_rules,
     check_callback_rules,
@@ -185,6 +185,7 @@
             key=key,
             help=help,
             form_id=current_form_id(self.dg),
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 

lib/streamlit/elements/widgets/data_editor.py

@@ -40,7 +40,7 @@
 from streamlit import logger as _logger
 from streamlit import type_util
 from streamlit.deprecation_util import deprecate_func_name
-from streamlit.elements.form import current_form_id
+from streamlit.elements.form import current_container_key, current_form_id
 from streamlit.elements.lib.column_config_utils import (
     INDEX_IDENTIFIER,
     ColumnConfigMapping,
@@ -874,6 +874,7 @@
             num_rows=num_rows,
             key=key,
             form_id=current_form_id(self.dg),
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 

lib/streamlit/elements/widgets/file_uploader.py

@@ -26,6 +26,7 @@
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
+    current_container_key,
     get_label_visibility_proto_value,
 )
 from streamlit.proto.Common_pb2 import FileUploaderState as FileUploaderStateProto
@@ -415,6 +416,7 @@ def _file_uploader(
             key=key,
             help=help,
             form_id=current_form_id(self.dg),
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 

lib/streamlit/elements/widgets/multiselect.py

@@ -23,6 +23,7 @@
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
+    current_container_key,
     get_label_visibility_proto_value,
     maybe_coerce_enum_sequence,
 )
@@ -310,6 +311,7 @@ def _multiselect(
             max_selections=max_selections,
             placeholder=placeholder,
             form_id=current_form_id(self.dg),
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 

lib/streamlit/elements/widgets/number_input.py

@@ -26,6 +26,7 @@
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
+    current_container_key,
     get_label_visibility_proto_value,
 )
 from streamlit.errors import StreamlitAPIException
@@ -301,6 +302,7 @@ def _number_input(
             help=help,
             placeholder=None if placeholder is None else str(placeholder),
             form_id=current_form_id(self.dg),
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 

lib/streamlit/elements/widgets/radio.py

@@ -23,6 +23,7 @@
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
+    current_container_key,
     get_label_visibility_proto_value,
     maybe_coerce_enum,
 )
@@ -272,6 +273,7 @@ def _radio(
             horizontal=horizontal,
             captions=captions,
             form_id=current_form_id(self.dg),
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 

lib/streamlit/elements/widgets/select_slider.py

@@ -25,6 +25,7 @@
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
+    current_container_key,
     get_label_visibility_proto_value,
     maybe_coerce_enum,
     maybe_coerce_enum_sequence,
@@ -299,6 +300,7 @@ def as_index_list(v: object) -> list[int]:
             key=key,
             help=help,
             form_id=current_form_id(self.dg),
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 

lib/streamlit/elements/widgets/selectbox.py

@@ -22,6 +22,7 @@
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
+    current_container_key,
     get_label_visibility_proto_value,
     maybe_coerce_enum,
 )
@@ -251,6 +252,7 @@ def _selectbox(
             help=help,
             placeholder=placeholder,
             form_id=current_form_id(self.dg),
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 

lib/streamlit/elements/widgets/slider.py

@@ -27,6 +27,7 @@
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
+    current_container_key,
     get_label_visibility_proto_value,
 )
 from streamlit.errors import StreamlitAPIException
@@ -384,6 +385,7 @@ def _slider(
             key=key,
             help=help,
             form_id=current_form_id(self.dg),
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 

lib/streamlit/elements/widgets/text_widgets.py

@@ -23,6 +23,7 @@
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
+    current_container_key,
     get_label_visibility_proto_value,
 )
 from streamlit.errors import StreamlitAPIException
@@ -277,6 +278,7 @@ def _text_input(
             autocomplete=autocomplete,
             placeholder=str(placeholder),
             form_id=current_form_id(self.dg),
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )
 
@@ -542,6 +544,7 @@ def _text_area(
             help=help,
             placeholder=str(placeholder),
             form_id=current_form_id(self.dg),
+            container_key=current_container_key(self.dg),
             page=ctx.page_script_hash if ctx else None,
         )