我现在有个需求是筛选某个时间段的内容，要定义DATE类型字段isodate_time用于检索，但我发现存储后还是字符串类型的，请教大佬有什么方法在添加数据的时候规定字段类型。
搜索了相关解答，要设置为db.serverDate()， 可我从前端传来的是data数组，能在ADD时追加isodate_time: db.serverDate()么？

云函数处理

exports.main = async(event, context) => {
    switch (event.action) {
        case 'AddWlog':
            {
                let data = event.data,
                    openid = data.openid;
                await db.collection('TABLE_WLOG').add({
                    data: data
                })
                await db.collection('TABLE_USER').doc(openid).update({
                    data: {
                        wlog_num: _.inc(1)
                    }
                })
                return {
                    msg: 'ok'
                }
            }
    }
}

发布页提交的数据

wx.cloud.callFunction({
    name: 'wlogfun',
    data: {
        action: 'AddWlog',
        data: {
            openid: wx.getStorageSync('openid'),
            content: that.data.content,
            picture: that.data.picList,
            location: that.data.location[0] || '',
            likes: 0,
            chats: 0,
            views: 0,
            is_top: that.data.set_top,
            is_locking: that.data.set_locking,
            is_secret: that.data.set_secret,
            is_delete: 0,
            //isodate_time: new Date(Date.now() + 8 * 60 * 60 * 1000),
            create_time: timeutil.TimeCode(new Date()),
            update_time: timeutil.TimeCode(new Date())
        }
    },
    success: res => {
        wx.showToast({
            title: '发布成功',
            icon: 'success',
            success: res => {
                setTimeout(() => {
                    let pages = getCurrentPages(), //获取当前页面的页面栈
                        lastPage = pages[pages.length - 2]; //获取上一个页面的页面栈
                    lastPage.setData({
                        page: 0,
                        wloglist: []
                    })
                    wx.navigateBack({
                        delta: 1
                    })
                }, 2000);
            }
        })
        wx.removeStorageSync('wlogDraft'); //清除缓存草稿
    },
    fail: res => {
        wx.showToast({
            icon: 'none',
            title: '发布失败',
        })
    }
})