微信小程序云数据库关于单条记录数组字段头部追加数据问题——unshift函数的用法

js代码：

const db = wx.cloud.database();

const _ = db.command

db.collection("questions").doc(that.data.id).update({

data: {

comments: _.unshift({

comment: e.detail.value.comment,

time: getCurrentTimeUtil.formatTime(new Date()),

avatarUrl: that.data.userInfo.avatarUrl,

nickName: that.data.userInfo.nickName,

})

},

success: function(res) {

wx.showToast({

title: '发布评论成功',

})

},

fail:function() {

 

}

})

测试  添加记录顺序依次是（与保存到数据库的顺序相反）：

"3":{"avatarUrl":"https://wx.qlogo.cn/mmopen/gfdgfdgfgfgdgdfgf","comment":"塞下秋来风景异","nickName":"傅华涛","time":"2018.10.26 08:30:38"}

"2":{"avatarUrl":"https://wx.qlogo.cn/mmopen/gfdgfdgfgfgdgdfgf","comment":"落霞与孤鹜齐飞，秋水共长天一色","nickName":"傅华涛","time":"2018.10.26 08:33:03"}

"1":{"avatarUrl":"https://wx.qlogo.cn/mmopen/gfdgfdgfgfgdgdfgf","comment":"空山新雨后，天气晚来秋","nickName":"傅华涛","time":"2018.10.26 08:33:24"}

"0":{"avatarUrl":"https://wx.qlogo.cn/mmopen/gfdgfdgfgfgdgdfgf","comment":"春花秋月何时了","nickName":"傅华涛","time":"2018.10.26 08:55:16"}

 

云数据库json数据：

"_id":W9G7Cgfdgfdgfgfgf

"_openid":gfgfgfdgfdgdfgdfdgfg

"avatarUrl":https://wx.qlogo.cn/mmopen/gfdgfdgfgfgdgdfgf

"comments":

"0":{"avatarUrl":"https://wx.qlogo.cn/mmopen/gfdgfdgfgfgdgdfgf","comment":"春花秋月何时了","nickName":"傅华涛","time":"2018.10.26 08:55:16"}

"1":{"avatarUrl":"https://wx.qlogo.cn/mmopen/gfdgfdgfgfgdgdfgf","comment":"空山新雨后，天气晚来秋","nickName":"傅华涛","time":"2018.10.26 08:33:24"}

"2":{"avatarUrl":"https://wx.qlogo.cn/mmopen/gfdgfdgfgfgdgdfgf","comment":"落霞与孤鹜齐飞，秋水共长天一色","nickName":"傅华涛","time":"2018.10.26 08:33:03"}

"3":{"avatarUrl":"https://wx.qlogo.cn/mmopen/gfdgfdgfgfgdgdfgf","comment":"塞下秋来风景异","nickName":"傅华涛","time":"2018.10.26 08:30:38"}

"nickName":傅华涛

"question":请写出含有“秋”的诗句

"time":2018/10/25 20:46:00