refactor: simplify variable pool key structure and improve type safety (#23732)

Signed-off-by: -LAN- <laipz8200@outlook.com>

api/core/workflow/nodes/variable_assigner/common/helpers.py

@@ -4,7 +4,7 @@ from typing import Any, TypeVar
 from pydantic import BaseModel
 
 from core.variables import Segment
-from core.variables.consts import MIN_SELECTORS_LENGTH
+from core.variables.consts import SELECTORS_LENGTH
 from core.variables.types import SegmentType
 
 # Use double underscore (`__`) prefix for internal variables
@@ -23,7 +23,7 @@ _T = TypeVar("_T", bound=MutableMapping[str, Any])
 
 
 def variable_to_processed_data(selector: Sequence[str], seg: Segment) -> UpdatedVariable:
-    if len(selector) < MIN_SELECTORS_LENGTH:
+    if len(selector) < SELECTORS_LENGTH:
         raise Exception("selector too short")
     node_id, var_name = selector[:2]
     return UpdatedVariable(

api/core/workflow/nodes/variable_assigner/v2/node.py

@@ -4,7 +4,7 @@ from typing import Any, Optional, cast
 
 from core.app.entities.app_invoke_entities import InvokeFrom
 from core.variables import SegmentType, Variable
-from core.variables.consts import MIN_SELECTORS_LENGTH
+from core.variables.consts import SELECTORS_LENGTH
 from core.workflow.constants import CONVERSATION_VARIABLE_NODE_ID
 from core.workflow.conversation_variable_updater import ConversationVariableUpdater
 from core.workflow.entities.node_entities import NodeRunResult
@@ -46,7 +46,7 @@ def _source_mapping_from_item(mapping: MutableMapping[str, Sequence[str]], node_
     selector = item.value
     if not isinstance(selector, list):
         raise InvalidDataError(f"selector is not a list, {node_id=}, {item=}")
-    if len(selector) < MIN_SELECTORS_LENGTH:
+    if len(selector) < SELECTORS_LENGTH:
         raise InvalidDataError(f"selector too short, {node_id=}, {item=}")
     selector_str = ".".join(selector)
     key = f"{node_id}.#{selector_str}#"