ADD file via upload

Exam.js

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+const mongoose = require('mongoose');
+
+const questionSchema = new mongoose.Schema({
+    type: {
+        type: String,
+        enum: ['single', 'multiple', 'text'],
+        required: true
+    },
+    question: {
+        type: String,
+        required: true
+    },
+    options: [String],
+    answer: mongoose.Schema.Types.Mixed, // 可以是索引、索引数组或字符串
+    score: {
+        type: Number,
+        required: true
+    }
+});
+
+const examSchema = new mongoose.Schema({
+    title: {
+        type: String,
+        required: true
+    },
+    description: String,
+    duration: { // 考试时长(分钟)
+        type: Number,
+        required: true
+    },
+    questions: [questionSchema],
+    createdBy: {
+        type: mongoose.Schema.Types.ObjectId,
+        ref: 'User',
+        required: true
+    },
+    createdAt: {
+        type: Date,
+        default: Date.now
+    },
+    isActive: {
+        type: Boolean,
+        default: true
+    }
+});
+
+module.exports = mongoose.model('Exam', examSchema);