refactor(models): Use the SQLAlchemy base model. (#19435)

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

api/models/workflow.py

@@ -9,7 +9,7 @@ if TYPE_CHECKING:
     from models.model import AppMode
 
 import sqlalchemy as sa
-from sqlalchemy import Index, PrimaryKeyConstraint, func
+from sqlalchemy import func
 from sqlalchemy.orm import Mapped, mapped_column
 
 import contexts
@@ -18,11 +18,11 @@ from core.helper import encrypter
 from core.variables import SecretVariable, Variable
 from factories import variable_factory
 from libs import helper
-from models.base import Base
-from models.enums import CreatedByRole
 
 from .account import Account
+from .base import Base
 from .engine import db
+from .enums import CreatedByRole
 from .types import StringUUID
 
 if TYPE_CHECKING:
@@ -768,17 +768,12 @@ class WorkflowAppLog(Base):
 
 class ConversationVariable(Base):
     __tablename__ = "workflow_conversation_variables"
-    __table_args__ = (
-        PrimaryKeyConstraint("id", "conversation_id", name="workflow_conversation_variables_pkey"),
-        Index("workflow__conversation_variables_app_id_idx", "app_id"),
-        Index("workflow__conversation_variables_created_at_idx", "created_at"),
-    )
 
     id: Mapped[str] = mapped_column(StringUUID, primary_key=True)
     conversation_id: Mapped[str] = mapped_column(StringUUID, nullable=False, primary_key=True)
-    app_id: Mapped[str] = mapped_column(StringUUID, nullable=False)
+    app_id: Mapped[str] = mapped_column(StringUUID, nullable=False, index=True)
     data = mapped_column(db.Text, nullable=False)
-    created_at = mapped_column(db.DateTime, nullable=False, server_default=func.current_timestamp())
+    created_at = mapped_column(db.DateTime, nullable=False, server_default=func.current_timestamp(), index=True)
     updated_at = mapped_column(
         db.DateTime, nullable=False, server_default=func.current_timestamp(), onupdate=func.current_timestamp()
     )