From e1d10605c954f1c0f3f16443ac3d65ff5164f932 Mon Sep 17 00:00:00 2001
From: yuliang_guo <anonymous@qq.com>
Date: Sat, 31 Jan 2026 11:21:39 +0800
Subject: [PATCH] =?UTF-8?q?fix:=20ExamService.start=5Fexam=E8=BF=94?=
 =?UTF-8?q?=E5=9B=9EID=E9=81=BF=E5=85=8D=E6=87=92=E5=8A=A0=E8=BD=BD?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

修改start_exam返回exam.id而不是整个Exam对象,
彻底避免SQLAlchemy异步会话的懒加载问题
---
 backend/app/api/v1/exam.py           |  4 ++--
 backend/app/services/exam_service.py | 10 ++++++----
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/backend/app/api/v1/exam.py b/backend/app/api/v1/exam.py
index dd17673..442b6d3 100644
--- a/backend/app/api/v1/exam.py
+++ b/backend/app/api/v1/exam.py
@@ -66,7 +66,7 @@ async def start_exam(
     user_id = current_user.id
     username = current_user.username
     
-    exam = await ExamService.start_exam(
+    exam_id = await ExamService.start_exam(
         db=db,
         user_id=user_id,
         course_id=request.course_id,
@@ -96,7 +96,7 @@ async def start_exam(
         )
     )
 
-    return ResponseModel(code=200, data=StartExamResponse(exam_id=exam.id), message="考试开始")
+    return ResponseModel(code=200, data=StartExamResponse(exam_id=exam_id), message="考试开始")
 
 
 @router.post("/submit", response_model=ResponseModel[SubmitExamResponse])
diff --git a/backend/app/services/exam_service.py b/backend/app/services/exam_service.py
index e682cf8..53a783e 100644
--- a/backend/app/services/exam_service.py
+++ b/backend/app/services/exam_service.py
@@ -20,7 +20,7 @@ class ExamService:
     @staticmethod
     async def start_exam(
         db: AsyncSession, user_id: int, course_id: int, question_count: int = 10
-    ) -> Exam:
+    ) -> int:
         """
         开始考试
 
@@ -31,7 +31,7 @@ class ExamService:
             question_count: 题目数量
 
         Returns:
-            Exam: 考试实例
+            int: 考试ID
         """
         # 检查课程是否存在
         course = await db.get(Course, course_id)
@@ -93,8 +93,10 @@ class ExamService:
         db.add(exam)
         await db.commit()
         await db.refresh(exam)
-
-        return exam
+        
+        # 返回exam.id而不是整个对象，避免懒加载问题
+        exam_id = exam.id
+        return exam_id
 
     @staticmethod
     async def submit_exam(