fix

mec-teacher/src/main/java/com/ym/mec/teacher/controller/ClassGroupController.java

@@ -80,7 +80,7 @@ public class ClassGroupController extends BaseController {
 
             Map<Integer, StudentSubjectDto> subjectDtoMap = subjectService.getSubjectByStudentId(collect);
             courseStudents.forEach(studentAttendanceViewDto -> {
-                if (studentAttendanceViewDto.getSubjectId() == null) {
+                if (studentAttendanceViewDto.getSubjectIdList() == null) {
                     StudentSubjectDto subjectDto = subjectDtoMap.getOrDefault(studentAttendanceViewDto.getUserId(), null);
                     if (subjectDto.getSubjectId() != null) {
                         studentAttendanceViewDto.setSubjectName(subjectDto.getSubjectName());