text: module.exports = app => {
      const mongoose = app.mongoose;
      const Schema = mongoose.Schema;
  
      const poemSchema = new Schema({
          key: {
              type: String,
              default: ""
          },
          // 故事名
          title: {
              type: String,
              default: ""
          },
          // 副标题
          subTitle: {
              type: String,
              default: ""
          },
          // 作者
          author: {
              type: String,
              default: ""
          },
          // 朝代
          dynasty: {
              type: String,
              default: ""
          },
          // 具体成语
          content: {
              type: String,
              default: ""
          },
          // 声音
          sound: {
              type: String,
              default: ""
          },
          //翻译
          fanyi: {
              type: String,
              default: ""
          },
          desc: {
              type: String,
              default: ""
          },
          // 年级
          level: {
              type: String,
              default: ""
          },
          // 是否已经学习过 0 - 未学习 1 - 已学习
          studied: {
              type: String,
              default: "0"
          },
          // 已学习次数
          learnTimes: {
              type: Number,
              default: 0
          },
          // 答错次数
          errorTimes: {
              type: Number,
              default: 0
          },
          // 答对次数
          successTimes: {
              type: Number,
              default: 0
          },
          // 上次学习时间
          lastLearnTime: {
              type: Date,
              default: null
          },
      }, {
          versionKey: false,
          timestamps: { updatedAt: 'lastLearnTime' }
      });
  
      return mongoose.model('poem', poemSchema);
  }