修复数据库连接错误，用户组功能待测试

api/controllers/quizController.ts

@@ -1,5 +1,6 @@
 import { Request, Response } from 'express';
 import { QuestionModel, QuizModel, SystemConfigModel } from '../models';
+import { Question } from '../models/question';
 
 export class QuizController {
   static async generateQuiz(req: Request, res: Response) {
@@ -122,8 +123,8 @@ export class QuizController {
       let totalScore = questions.reduce((sum, q) => sum + q.score, 0);
       while (totalScore < subject.totalScore) {
         // 获取所有类型的随机题目
-        const allTypes = Object.keys(subject.typeRatios).filter(type => subject.typeRatios[type] > 0);
-        if (allTypes.length === 0) break;
+      const allTypes = Object.keys(subject.typeRatios).filter(type => subject.typeRatios[type as keyof typeof subject.typeRatios] > 0);
+      if (allTypes.length === 0) break;
         
         const randomType = allTypes[Math.floor(Math.random() * allTypes.length)];
         const availableQuestions = await QuestionModel.getRandomQuestions(