text: const mongoose = require('mongoose')
  
  // 定义一个约定schema
  const schema = new mongoose.Schema({
      name:{
          type:String
      },
      items:[{
          image:{type:String},
          url:{type:String},
      }]
  
  
        
  })
  
  // 创建一个模型并导出
  module.exports = mongoose.model('Ad',schema)