修复了一个学生如果退课前端在请求批改数据时还向前端发送的错误；修复了未批改人数的统计bug

src/main/java/com/njuzr/eaibackend/mapper/StudentAssignmentMapper.java

@@ -5,6 +5,7 @@ import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
 import com.njuzr.eaibackend.po.Engagement;
 import com.njuzr.eaibackend.po.StudentAssignment;
 import com.njuzr.eaibackend.po.StudentAssignmentHistory;
+import com.njuzr.eaibackend.vo.EngageNumberVo;
 import org.apache.ibatis.annotations.Mapper;
 import org.apache.ibatis.annotations.Param;
 
@@ -25,6 +26,8 @@ public interface StudentAssignmentMapper extends BaseMapper<Engagement> {
 
     List<Engagement> findEngagementByAssignmentId(Long assignmentId);
 
+    EngageNumberVo countEngageNumberByCurrentClassStudents(@Param("assignmentId") Long assignmentId);
+
     void delete(Long studentId, Long assignmentId);
 
     String getTextContent(Long studentId, Long assignmentId);

src/main/java/com/njuzr/eaibackend/service/impl/AssignmentServiceImpl.java

@@ -519,8 +519,18 @@ public class AssignmentServiceImpl implements AssignmentService {
         List<Engagement> allRecords = studentAssignmentMapper.selectList(
                 new QueryWrapper<Engagement>()
                         .eq("assignment_id", assignmentId)
-                // 可以在此添加其他查询条件
+                        .exists("""
+                                SELECT 1
+                                FROM assignment a
+                                JOIN course_student cs ON cs.course_id = a.course_id
+                                WHERE a.assignment_id = student_assignment.assignment_id
+                                  AND cs.student_id = student_assignment.student_id
+                                """)
         );
+        if (allRecords.isEmpty()) {
+            throw MyException.create(HttpStatus.BAD_REQUEST, "当前作业没有可批改的在课学生");
+        }
+
         // 对记录进行排序：status为4或6的记录排到最后，其他记录保持原始顺序
         List<Engagement> sortedList = allRecords.stream()
                 .sorted(Comparator.comparing(
@@ -535,7 +545,7 @@ public class AssignmentServiceImpl implements AssignmentService {
                 break;
             }
         }
-        if (currentIndex == allRecords.size() - 1 || currentIndex == -1) {
+        if (currentIndex == sortedList.size() - 1 || currentIndex == -1) {
             return sortedList.get(0).getStudentId();
         }
 
@@ -548,11 +558,7 @@ public class AssignmentServiceImpl implements AssignmentService {
         if(assignment == null){
             throw MyException.create(HttpStatus.BAD_REQUEST, "作业不存在");
         }
-        if(assignment.getEngageNumber() != null && assignment.getCorrectNumber() != null){
-            return new EngageNumberVo(assignment.getEngageNumber(), assignment.getCorrectNumber());
-        } else {
-            throw MyException.create(HttpStatus.BAD_REQUEST, "未建立作业统计");
-        }
+        return studentAssignmentMapper.countEngageNumberByCurrentClassStudents(assignmentId);
     }
 
     private Assignment convertToPO(AssignmentDTO assignmentDTO) {

src/main/resources/mapper/StudentAssignmentMapper.xml

@@ -14,6 +14,23 @@
         WHERE assignment_id = #{assignmentId}
     </select>
 
+    <select id="countEngageNumberByCurrentClassStudents" resultType="com.njuzr.eaibackend.vo.EngageNumberVo">
+        SELECT
+            COUNT(*) AS engageNumber,
+            COALESCE(SUM(CASE WHEN sa.status IN (4, 6, 8) THEN 1 ELSE 0 END), 0) AS correctNumber
+        FROM student_assignment sa
+        WHERE sa.assignment_id = #{assignmentId}
+          AND EXISTS (
+              SELECT 1
+              FROM assignment a
+              JOIN `class` c ON c.course_id = a.course_id
+              JOIN class_student cs ON cs.class_id = c.class_id
+              JOIN users u ON u.official_number = cs.official_number
+              WHERE a.assignment_id = sa.assignment_id
+                AND u.id = sa.student_id
+          )
+    </select>
+
     <!--  通过studentId和assignmentID查找text_content  -->
     <select id="getTextContent" resultType="java.lang.String">
         SELECT text_content