模型设计如下

const RegistrationSheet = mongoose.model('RegistrationSheet', new Schema({
  doctorId: String,
  today: {
    time: String,
    date: {
      morning: [
        {
          number:Number,          
          patient: String
        }
      ],
      afternoon: [
        {
          number:Number,          
          patient: String
        }
      ]
    }
  },
  tomorrow: {
    time: String,
    date: {
      morning: [
        {
          number:Number,
          patient: String
        }
      ],
      afternoon: [
        {
          number:Number,          
          patient: String
        }
      ]
    }
  },
  afterTomorrow: {
    time: String,
    date: {
      morning: [
        {
          number:Number,          
          patient: String
        }
      ],
      afternoon: [
        {
          number:Number,          
          patient: String
        }
      ]
    }
  }
}))

现在我想在today的date的morning中插入一条数据应该怎么做，
根据前面的doctorId