feat: Add conversation variable persistence layer (#30531)

api/services/conversation_service.py

@@ -11,13 +11,13 @@ from core.app.entities.app_invoke_entities import InvokeFrom
 from core.db.session_factory import session_factory
 from core.llm_generator.llm_generator import LLMGenerator
 from core.variables.types import SegmentType
-from core.workflow.nodes.variable_assigner.common.impl import conversation_variable_updater_factory
 from extensions.ext_database import db
 from factories import variable_factory
 from libs.datetime_utils import naive_utc_now
 from libs.infinite_scroll_pagination import InfiniteScrollPagination
 from models import Account, ConversationVariable
 from models.model import App, Conversation, EndUser, Message
+from services.conversation_variable_updater import conversation_variable_updater_factory
 from services.errors.conversation import (
     ConversationNotExistsError,
     ConversationVariableNotExistsError,

api/services/conversation_variable_updater.py

@@ -0,0 +1,30 @@
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from core.variables.variables import Variable
+from extensions.ext_database import db
+from models import ConversationVariable
+
+
+class ConversationVariableNotFoundError(Exception):
+    pass
+
+
+class ConversationVariableUpdaterImpl:
+    def update(self, conversation_id: str, variable: Variable) -> None:
+        stmt = select(ConversationVariable).where(
+            ConversationVariable.id == variable.id, ConversationVariable.conversation_id == conversation_id
+        )
+        with Session(db.engine) as session:
+            row = session.scalar(stmt)
+            if not row:
+                raise ConversationVariableNotFoundError("conversation variable not found in the database")
+            row.data = variable.model_dump_json()
+            session.commit()
+
+    def flush(self) -> None:
+        pass
+
+
+def conversation_variable_updater_factory() -> ConversationVariableUpdaterImpl:
+    return ConversationVariableUpdaterImpl()