patch

src/Jiaowu.Api/Controllers/CourseSelectionsController.cs

@@ -85,15 +85,16 @@ public sealed class CourseSelectionsController(
         CancellationToken cancellationToken)
     {
         var source = ApplyEnrollmentFilters(ScopedEnrollments(), query);
-        var students = source.Select(x => new EnrollmentStudentIdentity(
-            x.StudentId, x.Student!.StudentNumber, x.Student.Name,
-            x.Student.AdministrativeClass!.Major!.Name,
-            x.Student.AdministrativeClass.Name, x.Student.AdministrativeClass.Grade));
-        var total = await students.Distinct().CountAsync(cancellationToken);
+        var matchingStudentIds = source.Select(x => x.StudentId).Distinct();
+        var total = await matchingStudentIds.CountAsync(cancellationToken);
         var page = Math.Max(1, query.Page);
         var pageSize = Math.Clamp(query.PageSize, 1, 100);
-        var pageStudents = await students.Distinct()
+        var pageStudents = await db.Students.AsNoTracking()
+            .Where(x => matchingStudentIds.Contains(x.Id))
             .OrderBy(x => x.StudentNumber).Skip((page - 1) * pageSize).Take(pageSize)
+            .Select(x => new EnrollmentStudentIdentity(
+                x.Id, x.StudentNumber, x.Name, x.AdministrativeClass!.Major!.Name,
+                x.AdministrativeClass.Name, x.AdministrativeClass.Grade))
             .ToListAsync(cancellationToken);
         var studentIds = pageStudents.Select(x => x.StudentId).ToArray();
         var enrollments = await ProjectEnrollments(OrderEnrollments(source.Where(x =>