优化学业预警检测：

通知阶段移除逐条查询学生、规则、辅导员的 N+1 数据库访问。
不及格预警从“每个学生一次统计 + 一次查重”改为批量分组统计与一次性已有记录集合查询。
保持原有阈值、去重、通知内容与权限行为。

src/Jiaowu.Api/Controllers/EvaluationsController.cs

@@ -391,81 +391,90 @@ public sealed class EvaluationsController(
         if (taskIds.Count == 0)
             return Ok(new { Tasks = Array.Empty<object>() });
 
-        var setups = await db.EvaluationSetups.AsNoTracking()
-            .Where(x => x.Status == EvaluationSetupStatus.Closed)
-            .Include(x => x.Dimensions.OrderBy(d => d.SortOrder))
-            .OrderByDescending(x => x.AcademicTerm!.StartDate)
+        var taskSummaries = await db.EvaluationRecords.AsNoTracking()
+            .WhereIn(taskIds, record => record.TeachingTaskId)
+            .Where(record => record.EvaluationSetup!.Status == EvaluationSetupStatus.Closed)
+            .GroupBy(record => new
+            {
+                record.EvaluationSetupId,
+                SetupName = record.EvaluationSetup!.Name,
+                SetupStartDate = record.EvaluationSetup.AcademicTerm!.StartDate,
+                record.TeachingTaskId,
+                TaskNumber = record.TeachingTask!.TaskNumber,
+                TaskName = record.TeachingTask.Name,
+                record.TeachingTask.AcademicTermId,
+                CourseCode = record.TeachingTask.Course!.Code,
+                CourseName = record.TeachingTask.Course.Name
+            })
+            .Select(group => new
+            {
+                group.Key,
+                StudentCount = group.Count(),
+                AverageTotal = group.Average(record =>
+                    record.Scores.Sum(score => score.Score))
+            })
+            .OrderByDescending(x => x.Key.SetupStartDate)
+            .ThenBy(x => x.Key.CourseCode)
+            .ThenBy(x => x.Key.TaskNumber)
             .ToListAsync(cancellationToken);
 
-        var result = new List<object>();
-        foreach (var setup in setups)
-        {
-            var setupTaskIds = await db.EvaluationRecords.AsNoTracking()
-                .Where(r => r.EvaluationSetupId == setup.Id)
-                .WhereIn(taskIds, r => r.TeachingTaskId)
-                .Select(r => r.TeachingTaskId)
-                .Distinct()
-                .ToListAsync(cancellationToken);
-
-            foreach (var taskId in setupTaskIds)
+        var dimensionSummaries = await (
+            from score in db.EvaluationScores.AsNoTracking()
+            join record in db.EvaluationRecords.AsNoTracking()
+                on score.EvaluationRecordId equals record.Id
+            join dimension in db.EvaluationDimensions.AsNoTracking()
+                on score.EvaluationDimensionId equals dimension.Id
+            where taskIds.Contains(record.TeachingTaskId) &&
+                  record.EvaluationSetup!.Status == EvaluationSetupStatus.Closed
+            group score by new
             {
-                var task = await db.TeachingTasks.AsNoTracking()
-                    .Where(x => x.Id == taskId)
-                    .Select(x => new
-                    {
-                        x.Id,
-                        x.TaskNumber,
-                        x.Name,
-                        x.AcademicTermId,
-                        CourseCode = x.Course!.Code,
-                        CourseName = x.Course.Name
-                    })
-                    .FirstOrDefaultAsync(cancellationToken);
-                if (task is null) continue;
-
-                var records = await db.EvaluationRecords.AsNoTracking()
-                    .Where(r => r.EvaluationSetupId == setup.Id &&
-                                r.TeachingTaskId == taskId)
-                    .Include(r => r.Scores)
-                    .ToListAsync(cancellationToken);
-
-                if (records.Count == 0) continue;
-
-                var dimensionResults = setup.Dimensions.Select(dim =>
-                {
-                    var scores = records
-                        .SelectMany(r => r.Scores)
-                        .Where(s => s.EvaluationDimensionId == dim.Id)
-                        .Select(s => (double)s.Score)
-                        .ToList();
-                    return new
-                    {
-                        DimensionId = dim.Id,
-                        DimensionName = dim.Name,
-                        MaxScore = dim.MaxScore,
-                        AverageScore = scores.Count > 0
-                            ? Math.Round(scores.Average(), 1) : 0,
-                        TotalScore = scores.Sum(),
-                        Count = scores.Count
-                    };
-                }).ToList();
-
-                var totalAvg = records
-                    .Select(r => (double)r.Scores.Sum(s => s.Score))
-                    .ToList();
-
-                result.Add(new
-                {
-                    SetupId = setup.Id,
-                    setup.Name,
-                    Task = task,
-                    StudentCount = records.Count,
-                    AverageTotal = totalAvg.Count > 0
-                        ? Math.Round(totalAvg.Average(), 1) : 0,
-                    Dimensions = dimensionResults
-                });
+                record.EvaluationSetupId,
+                record.TeachingTaskId,
+                dimension.Id,
+                dimension.Name,
+                dimension.MaxScore,
+                dimension.SortOrder
             }
-        }
+            into scoreGroup
+            select new
+            {
+                scoreGroup.Key,
+                AverageScore = scoreGroup.Average(score => score.Score),
+                TotalScore = scoreGroup.Sum(score => score.Score),
+                Count = scoreGroup.Count()
+            })
+            .ToListAsync(cancellationToken);
+
+        var dimensionsByTask = dimensionSummaries
+            .GroupBy(item => (item.Key.EvaluationSetupId, item.Key.TeachingTaskId))
+            .ToDictionary(
+                group => group.Key,
+                group => (IReadOnlyCollection<TeacherEvaluationDimensionResult>)group
+                    .OrderBy(item => item.Key.SortOrder)
+                    .Select(item => new TeacherEvaluationDimensionResult(
+                        item.Key.Id,
+                        item.Key.Name,
+                        item.Key.MaxScore,
+                        Math.Round((double)item.AverageScore, 1),
+                        item.TotalScore,
+                        item.Count))
+                    .ToArray());
+        var result = taskSummaries.Select(item => new TeacherEvaluationTaskResult(
+            item.Key.EvaluationSetupId,
+            item.Key.SetupName,
+            new TeacherEvaluationTask(
+                item.Key.TeachingTaskId,
+                item.Key.TaskNumber,
+                item.Key.TaskName,
+                item.Key.AcademicTermId,
+                item.Key.CourseCode,
+                item.Key.CourseName),
+            item.StudentCount,
+            Math.Round((double)item.AverageTotal, 1),
+            dimensionsByTask.GetValueOrDefault(
+                (item.Key.EvaluationSetupId, item.Key.TeachingTaskId),
+                Array.Empty<TeacherEvaluationDimensionResult>())))
+            .ToArray();
 
         return Ok(new { Tasks = result });
     }
@@ -594,3 +603,27 @@ public sealed record SubmitEvaluationRequest(
 public sealed record EvaluationScoreRequest(
     Guid DimensionId,
     int Score);
+
+public sealed record TeacherEvaluationTaskResult(
+    Guid SetupId,
+    string SetupName,
+    TeacherEvaluationTask Task,
+    int StudentCount,
+    double AverageTotal,
+    IReadOnlyCollection<TeacherEvaluationDimensionResult> Dimensions);
+
+public sealed record TeacherEvaluationTask(
+    Guid Id,
+    string TaskNumber,
+    string Name,
+    Guid AcademicTermId,
+    string CourseCode,
+    string CourseName);
+
+public sealed record TeacherEvaluationDimensionResult(
+    Guid DimensionId,
+    string DimensionName,
+    int MaxScore,
+    double AverageScore,
+    decimal TotalScore,
+    int Count);

src/Jiaowu.Api/Controllers/OfficialDocumentsController.cs

@@ -227,14 +227,24 @@ public sealed class OfficialDocumentsController(
     [Authorize(Roles = Managers)]
     public async Task<ActionResult> DownloadHistory(
         Guid id,
-        CancellationToken cancellationToken)
+        CancellationToken cancellationToken,
+        int page = 1,
+        int pageSize = 20)
     {
+        if (page < 1 || pageSize is < 1 or > 100)
+            return ValidationProblem("页码必须大于 0，且每页条数应在 1 至 100 之间。");
+
         if (!await AccessibleDocuments().AnyAsync(x => x.Id == id, cancellationToken))
             return NotFound();
 
-        return Ok(await db.OfficialDocumentDownloads.AsNoTracking()
+        var source = db.OfficialDocumentDownloads.AsNoTracking()
             .Where(x => x.OfficialDocumentId == id)
             .OrderByDescending(x => x.CreatedAt)
+            .ThenByDescending(x => x.Id);
+        var total = await source.CountAsync(cancellationToken);
+        var items = await source
+            .Skip((page - 1) * pageSize)
+            .Take(pageSize)
             .Select(x => new
             {
                 x.Id,
@@ -244,7 +254,8 @@ public sealed class OfficialDocumentsController(
                 x.IpAddress,
                 x.UserAgent
             })
-            .ToListAsync(cancellationToken));
+            .ToListAsync(cancellationToken);
+        return Ok(new PagedResult<object>(items, total, page, pageSize));
     }
 
     [HttpPost("{id:guid}/invalidate")]

src/Jiaowu.Api/Controllers/WarningsController.cs

@@ -101,17 +101,23 @@ public sealed class WarningsController(AppDbContext db, ICurrentUserDataScope sc
             db.WarningRecords.AddRange(generated);
             await db.SaveChangesAsync(ct);
 
+            var studentsById = studentInfos.ToDictionary(student => student.Id);
+            var rulesByType = rules.ToDictionary(rule => rule.Type);
+            var classIds = studentInfos.Select(student => student.ClassId).Distinct().ToArray();
+            var counselorsByClass = await db.AdministrativeClasses.AsNoTracking()
+                .WhereIn(classIds, item => item.Id)
+                .Where(item => item.CounselorUserId != null)
+                .Select(item => new { item.Id, CounselorUserId = item.CounselorUserId!.Value })
+                .ToDictionaryAsync(item => item.Id, item => item.CounselorUserId, ct);
             foreach (var w in generated)
             {
-                var si = studentInfos.First(s => s.Id == w.StudentId);
-                var r = rules.First(r => r.Type == w.Type);
+                var si = studentsById[w.StudentId];
+                var r = rulesByType[w.Type];
                 if (r.NotifyStudent && si.UserId.HasValue)
                     await NotificationService.SendAsync(db, si.UserId.Value, "学业预警", w.Detail, "/warnings", ct, NotificationCategory.Warning);
-                if (r.NotifyCounselor)
+                if (r.NotifyCounselor && counselorsByClass.TryGetValue(si.ClassId, out var counselorId))
                 {
-                    var counselorId = await db.AdministrativeClasses.Where(c => c.Id == si.ClassId && c.CounselorUserId != null).Select(c => c.CounselorUserId!.Value).FirstOrDefaultAsync(ct);
-                    if (counselorId != default)
-                        await NotificationService.SendAsync(db, counselorId, "学生学业预警", $"{si.Name}：{w.Detail}", "/warnings", ct, NotificationCategory.Warning);
+                    await NotificationService.SendAsync(db, counselorId, "学生学业预警", $"{si.Name}：{w.Detail}", "/warnings", ct, NotificationCategory.Warning);
                 }
             }
         }
@@ -197,17 +203,31 @@ public sealed class WarningsController(AppDbContext db, ICurrentUserDataScope sc
     // ═══════════ Detection logic ═══════════
     private async Task<List<WarningRecord>> DetectFailedCredits(WarningRule rule, Guid termId, List<StudentInfo> students, CancellationToken ct)
     {
-        var records = new List<WarningRecord>();
-        foreach (var s in students)
-        {
-            var failed = await db.GradeRecords.CountAsync(x => x.StudentId == s.Id && x.GradeSheet!.TeachingTask!.AcademicTermId == termId && x.GradeSheet.Status == GradeSheetStatus.Published && x.TotalScore < 60, ct);
-            if (failed >= rule.Threshold)
+        var studentIds = students.Select(student => student.Id).ToArray();
+        var existingStudentIds = await db.WarningRecords.AsNoTracking()
+            .Where(record => record.AcademicTermId == termId && record.Type == rule.Type)
+            .Select(record => record.StudentId)
+            .ToHashSetAsync(ct);
+        var failedByStudent = await db.GradeRecords.AsNoTracking()
+            .Where(record => studentIds.Contains(record.StudentId) &&
+                             record.GradeSheet!.TeachingTask!.AcademicTermId == termId &&
+                             record.GradeSheet.Status == GradeSheetStatus.Published &&
+                             record.TotalScore < 60)
+            .GroupBy(record => record.StudentId)
+            .Select(group => new { StudentId = group.Key, Failed = group.Count() })
+            .ToListAsync(ct);
+        return failedByStudent
+            .Where(item => item.Failed >= rule.Threshold &&
+                           !existingStudentIds.Contains(item.StudentId))
+            .Select(item => new WarningRecord
             {
-                if (await db.WarningRecords.AnyAsync(x => x.StudentId == s.Id && x.AcademicTermId == termId && x.Type == WarningType.FailedCredits, ct)) continue;
-                records.Add(new WarningRecord { StudentId = s.Id, Type = rule.Type, TriggerValue = failed, Detail = $"不及格课程 {failed} 门，达到预警阈值 {rule.Threshold} 门。", AcademicTermId = termId });
-            }
-        }
-        return records;
+                StudentId = item.StudentId,
+                Type = rule.Type,
+                TriggerValue = item.Failed,
+                Detail = $"不及格课程 {item.Failed} 门，达到预警阈值 {rule.Threshold} 门。",
+                AcademicTermId = termId
+            })
+            .ToList();
     }
 
     private async Task<List<WarningRecord>> DetectLowGPA(WarningRule rule, Guid termId, List<StudentInfo> students, CancellationToken ct)