fix: resolve 5 review findings

Critical 1: Remove broken '钉钉绑定' tab (IntegConfig) — deleted /rbac/user-ding-mappings calls
Critical 2: Fix decorator placement in CreateClassDto — @IsOptional @IsArray restored to teachers
Important 1: Restore sync.service.spec.ts from 1fa3363, strip importDingTalkUsers tests
Important 2: Fix N+1 in batchImportStudents — batched find/save with In() operator
Important 3: Add migrate-student-ding-mapping.sql

apps/server/src/classes/classes.service.ts

@@ -134,42 +134,63 @@ export class ClassesService {
     const classEntity = await this.classRepo.findOne({ where: { id: classId } });
     if (!classEntity) throw new NotFoundException('班级不存在');
 
-    let imported = 0;
-    let skipped = 0;
+    if (dingUserIds.length === 0) return { imported: 0, skipped: 0 };
 
-    for (const dingUserId of dingUserIds) {
-      let mapping = await this.studentDingMappingRepo.findOne({ where: { dingUserId } });
-      let studentId: number;
+    // 1. Fetch all existing ding mappings in one query
+    const existingMappings = await this.studentDingMappingRepo.find({
+      where: { dingUserId: In(dingUserIds) },
+    });
+    const dingToStudentId = new Map(existingMappings.map(m => [m.dingUserId, m.studentId]));
 
-      if (mapping) {
-        studentId = mapping.studentId;
-      } else {
-        const student = this.studentRepo.create({
+    // 2. Batch create students for new dingUserIds
+    const newDingUserIds = dingUserIds.filter(id => !dingToStudentId.has(id));
+    if (newDingUserIds.length > 0) {
+      const newStudents = newDingUserIds.map(dingUserId =>
+        this.studentRepo.create({
           name: `dd_${dingUserId}`,
           status: 'active',
           departmentId: classEntity.departmentId ?? undefined,
-        });
-        const saved = await this.studentRepo.save(student);
-        studentId = saved.id;
-        mapping = this.studentDingMappingRepo.create({ dingUserId, studentId });
-        await this.studentDingMappingRepo.save(mapping);
+        })
+      );
+      const savedStudents = await this.studentRepo.save(newStudents);
+
+      const newMappings = savedStudents.map((s, i) =>
+        this.studentDingMappingRepo.create({ dingUserId: newDingUserIds[i], studentId: s.id })
+      );
+      await this.studentDingMappingRepo.save(newMappings);
+
+      for (let i = 0; i < newDingUserIds.length; i++) {
+        dingToStudentId.set(newDingUserIds[i], savedStudents[i].id);
       }
+    }
 
-      const existing = await this.classStudentRepo.findOne({
-        where: { classId, studentId },
+    // 3. Fetch existing class-student links in one query
+    const allStudentIds = Array.from(dingToStudentId.values());
+    const alreadyInClass = new Set<number>();
+    if (allStudentIds.length > 0) {
+      const existingClassStudents = await this.classStudentRepo.find({
+        where: { classId, studentId: In(allStudentIds) },
       });
-      if (existing) { skipped++; continue; }
+      for (const cs of existingClassStudents) {
+        alreadyInClass.add(cs.studentId);
+      }
+    }
 
-      await this.classStudentRepo.save(
+    // 4. Batch insert new class-student records
+    const newClassStudents = allStudentIds
+      .filter(sid => !alreadyInClass.has(sid))
+      .map(studentId =>
         this.classStudentRepo.create({
           classId, studentId, status: 'active',
           joinDate: new Date().toISOString().slice(0, 10),
-        }),
+        })
       );
-      imported++;
+
+    if (newClassStudents.length > 0) {
+      await this.classStudentRepo.save(newClassStudents);
     }
 
-    return { imported, skipped };
+    return { imported: newClassStudents.length, skipped: alreadyInClass.size };
   }
   async update(id: number, dto: UpdateClassDto) {
     const cls = await this.classRepo.findOne({ where: { id } });

apps/server/src/classes/dto/class.dto.ts

@@ -42,12 +42,12 @@ export class CreateClassDto {
   @IsOptional() @IsArray()
   studentIds?: number[];
 
-  @IsOptional() @IsArray()
-
   @IsArray()
   @IsString({ each: true })
   @IsOptional()
   dingUserIds?: string[];
+
+  @IsOptional() @IsArray()
   teachers?: Array<{ userId: number; roleType: string; subject?: string }>;
 }