微信小程序开发，用setData()赋值变量数组失败！

Question

问题遇到的现象和发生背景

微信小程序开发，用setData()赋值变量数组，失败！无报错 就是复制不上

遇到的现象和发生背景，请写出第一个错误信息

无报错，想要赋值的数组 数据不改变。

用代码块功能插入代码，请勿粘贴截图。 不用代码块回答率下降 50%

<view style="padding: 100rpx 0 30rpx 0;">
<text class="title">选择你要推广的平台</text>
</view>
<view class="mast">
  <view wx:for="{{menu_info}}" class="{{item.class}}" bindtap="onXzPt" data-index="{{item.id}}">
    {{item.name}}
  </view>
</view>

data: {
  menu_info:[
    {id:0,name: "抖音",class: "item",select: 1},
    {id:1,name: "快手",class: "item_f",select: 0},
    {id:2,name: "视频号",class: "item_f",select: 0},
    {id:3,name: "美团",class: "item_f",select: 0},
    {id:4,name: "小红书",class: "item_f",select: 0}
  ]
  },
  onXzPt:function (e) {
    var that = this
    let oncklik = e.currentTarget.dataset.index
    for (var i in that.data.menu_info){
      let menuid = that.data.menu_info[i].id
      var newclass = "that.data.menu_info["+i+"].class"
      if(menuid == oncklik){
        that.setData({
          [newclass] : 'item'
        })
        console.log(newclass)
        console.log(that.data.menu_info[i].class)
      }
      else{
      }
      }
  },


![img](https://img-mid.csdnimg.cn/release/static/image/mid/ask/442249896076190.png "#left")

运行结果及详细报错内容

that.data.menu_info[3].class
pt.js? [sm]:27 item_f

我的解答思路和尝试过的方法，不写自己思路的，回答率下降 60%

所有的办法都试过了，能想的能查的都用过了，还是不行，请帮助。

我想要达到的结果，如果你需要快速回答，请尝试 “付费悬赏”

Answer 1

Page({
  data: {
    menu_info: [{
        id: 0,
        name: "抖音",
        class: "item",
        select: 1
      },
      {
        id: 1,
        name: "快手",
        class: "item_f",
        select: 0
      },
      {
        id: 2,
        name: "视频号",
        class: "item_f",
        select: 0
      },
      {
        id: 3,
        name: "美团",
        class: "item_f",
        select: 0
      },
      {
        id: 4,
        name: "小红书",
        class: "item_f",
        select: 0
      }
    ]
  },
  onXzPt: function (e) {
    var that = this
    let oncklik = e.currentTarget.dataset.index

    // 获取data数据的副本
    let changeMenus = {
      ...that.data.menu_info
    }
    for (var i in changeMenus) {
      let menu = changeMenus[i]
      let menuid = menu.id
      if (menuid == oncklik) {
        menu.class = 'item'
        //将整个menu_info赋值
        that.setData({
          menu_info: changeMenus
        })
        console.log(that.data.menu_info[i].class)
        break
      } else {}
    }
  },
})

Answer 2

你要更新的是这个变量menu_info，代码修改如下：

Page({data: {
  menu_info:[
    {id:0,name: "抖音",class: "item",select: 1},
    {id:1,name: "快手",class: "item_f",select: 0},
    {id:2,name: "视频号",class: "item_f",select: 0},
    {id:3,name: "美团",class: "item_f",select: 0},
    {id:4,name: "小红书",class: "item_f",select: 0}
  ]
  },
  onXzPt:function (e) {
    var that = this
    let oncklik = e.currentTarget.dataset.index
    //修改如下
    let menu_info = that.data.menu_info;
    for (var i in that.data.menu_info){
      let menuid = that.data.menu_info[i].id
      let item = menu_info[i];
      if(menuid == oncklik){
        item.class = 'item';
        that.setData({
          menu_info : menu_info
        })
        console.log(menu_info[i])
        console.log(that.data.menu_info[i].class)
      }
      else{
      }
      }
  },
})

Answer 3

微信小程序使用this.setData()遇到的问题及解决方案详解
https://www.jb51.net/article/260286.htm

Answer 4

这里这篇【setData()方法的使用和注意事项】，提供给你做参考，助力你理解：https://blog.csdn.net/qq_38595560/article/details/81565925?spm=1001.2101.3001.6650.14&utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogCommendFromBaidu%7ERate-14-81565925-blog-108979975.pc_relevant_3mothn_strategy_and_data_recovery&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogCommendFromBaidu%7ERate-14-81565925-blog-108979975.pc_relevant_3mothn_strategy_and_data_recovery&utm_relevant_index=25

Answer 5

你想给数组中的某个对象的某个属性重新赋值，可以尝试声明一个变量复制原有数组，然后对这个变量进行操作，最后再把这个变量重新赋值给原有数组。参考这样：

onXzPt: function (e) {
        var that = this
        let oncklik = e.currentTarget.dataset.index
        let copyMenu_info = JSON.parse(JSON.stringify(that.data.menu_info));
        for (var i in copyMenu_info) {
            let menuid = copyMenu_info[i].id
            var newclass = copyMenu_info[i].class
            if (menuid == oncklik) {
                copyMenu_info.class = newclass; //给原有class赋值;
                copyMenu_info. [新增属性名] = newclass; //如果想新增属性，则给新增的属性赋值;
                break; //结束for循环
            }
        }
        //在此处重新赋值
        this.setData({
            menu_info: copyMenu_info
        })
    }

另外，声明数据的时候建议不要使用关键字 "class" 作为key; 还有为了性能优化，for循环中如果满足了条件，则可以终止for循环了，