refactor: fix N+1 query issue in workflow comments

api/models/comment.py

@@ -70,11 +70,15 @@ class WorkflowComment(Base):
     @property
     def created_by_account(self):
         """Get creator account."""
+        if hasattr(self, "_created_by_account_cache"):
+            return self._created_by_account_cache
         return db.session.get(Account, self.created_by)
 
     @property
     def resolved_by_account(self):
         """Get resolver account."""
+        if hasattr(self, "_resolved_by_account_cache"):
+            return self._resolved_by_account_cache
         if self.resolved_by:
             return db.session.get(Account, self.resolved_by)
         return None
@@ -147,6 +151,8 @@ class WorkflowCommentReply(Base):
     @property
     def created_by_account(self):
         """Get creator account."""
+        if hasattr(self, "_created_by_account_cache"):
+            return self._created_by_account_cache
         return db.session.get(Account, self.created_by)
 
 
@@ -186,4 +192,6 @@ class WorkflowCommentMention(Base):
     @property
     def mentioned_user_account(self):
         """Get mentioned account."""
+        if hasattr(self, "_mentioned_user_account_cache"):
+            return self._mentioned_user_account_cache
         return db.session.get(Account, self.mentioned_user_id)

api/services/workflow_comment_service.py

@@ -1,4 +1,5 @@
 import logging
+from collections.abc import Sequence
 from typing import Optional
 
 from sqlalchemy import desc, select
@@ -9,6 +10,7 @@ from extensions.ext_database import db
 from libs.datetime_utils import naive_utc_now
 from libs.helper import uuid_value
 from models import WorkflowComment, WorkflowCommentMention, WorkflowCommentReply
+from models.account import Account
 
 logger = logging.getLogger(__name__)
 
@@ -25,7 +27,7 @@ class WorkflowCommentService:
             raise ValueError("Comment content cannot exceed 1000 characters")
 
     @staticmethod
-    def get_comments(tenant_id: str, app_id: str) -> list[WorkflowComment]:
+    def get_comments(tenant_id: str, app_id: str) -> Sequence[WorkflowComment]:
         """Get all comments for a workflow."""
         with Session(db.engine) as session:
             # Get all comments with eager loading
@@ -37,10 +39,42 @@ class WorkflowCommentService:
             )
 
             comments = session.scalars(stmt).all()
+
+            # Batch preload all Account objects to avoid N+1 queries
+            WorkflowCommentService._preload_accounts(session, comments)
+
             return comments
 
     @staticmethod
-    def get_comment(tenant_id: str, app_id: str, comment_id: str, session: Session = None) -> WorkflowComment:
+    def _preload_accounts(session: Session, comments: Sequence[WorkflowComment]) -> None:
+        """Batch preload Account objects for comments, replies, and mentions."""
+        # Collect all user IDs
+        user_ids: set[str] = set()
+        for comment in comments:
+            user_ids.add(comment.created_by)
+            if comment.resolved_by:
+                user_ids.add(comment.resolved_by)
+            user_ids.update(reply.created_by for reply in comment.replies)
+            user_ids.update(mention.mentioned_user_id for mention in comment.mentions)
+
+        if not user_ids:
+            return
+
+        # Batch query all accounts
+        accounts = session.scalars(select(Account).where(Account.id.in_(user_ids))).all()
+        account_map = {str(account.id): account for account in accounts}
+
+        # Cache accounts on objects
+        for comment in comments:
+            comment._created_by_account_cache = account_map.get(comment.created_by)
+            comment._resolved_by_account_cache = account_map.get(comment.resolved_by) if comment.resolved_by else None
+            for reply in comment.replies:
+                reply._created_by_account_cache = account_map.get(reply.created_by)
+            for mention in comment.mentions:
+                mention._mentioned_user_account_cache = account_map.get(mention.mentioned_user_id)
+
+    @staticmethod
+    def get_comment(tenant_id: str, app_id: str, comment_id: str, session: Session | None = None) -> WorkflowComment:
         """Get a specific comment."""
 
         def _get_comment(session: Session) -> WorkflowComment:
@@ -58,6 +92,9 @@ class WorkflowCommentService:
             if not comment:
                 raise NotFound("Comment not found")
 
+            # Preload accounts to avoid N+1 queries
+            WorkflowCommentService._preload_accounts(session, [comment])
+
             return comment
 
         if session is not None:
@@ -75,7 +112,7 @@ class WorkflowCommentService:
         position_x: float,
         position_y: float,
         mentioned_user_ids: Optional[list[str]] = None,
-    ) -> WorkflowComment:
+    ) -> dict:
         """Create a new workflow comment."""
         WorkflowCommentService._validate_content(content)
 
@@ -247,7 +284,7 @@ class WorkflowCommentService:
     @staticmethod
     def update_reply(
         reply_id: str, user_id: str, content: str, mentioned_user_ids: Optional[list[str]] = None
-    ) -> WorkflowCommentReply:
+    ) -> dict:
         """Update a comment reply."""
         WorkflowCommentService._validate_content(content)