Question

我正在尝试在减速器中更新嵌套数据。使用以下操作，我将在我的reducer中返回一个数组映射。但是我的状态没有改变：

case "SUBMIT_ANSWER":
        const { current, results, completed } = action.data;
        return state.map(video =>
            video.id === action.id
                ? { ...video, current, results, completed }
                : video
        );

操作：

{
   type: "SUBMIT_ANSWER", data: {…}}
   data:
   completed: false
   current: 1
   id: 142
   results: {correctAnswers: 1, score: 5}
}

需要更新的数据：

{ 
   videos: [{
    bookMarked: false
    completed: false
    correctScore: 5
    current: 0
    description: "<p>Lorem ipsum dolor sit amet</p>↵"
    iconPath: "require('../assets/images/venepuncture.png')"
    id: 142
    preview: "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut"
    questions: (15) [{…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}]
    results: {score: 0, correctAnswers: 0}
    title: "Venepuncture"
    totalScore: 50
    youtubeVideo: "cxcxcx"
}
......
]}

Answer 1

假设

var state = {
    videos: [...]
}

您必须使用Object.assign来获取具有所需更改的新状态对象（请勿更改原始状态）

const { current, results, completed } = action.data;
return Object.assign({}, state, {
   videos: state.videos.map(...)
});

Answer 2

假定以下嵌套状态：

#include <algorithm>
#include <iostream>
#include <vector>
#include <iterator>
#include <range/v3/view/filter.hpp>
#include <range/v3/view/transform.hpp>

int main()
{

   std::vector<int> items = { 1, 3, 6, 8, 13, 17 };
   std::vector<int> subitems = { 3, 6, 17 };
   auto predicate = [&](int& n){
       for(auto& s : subitems)
        if(n == s)
            return true;
        return false; 
        };
   auto result = items | ranges::view::filter(predicate);

   for (auto& n : result)
   {
      std::cout << n << '\n';
   }
   for(auto it = result.begin(); it != result.end(); ++it )
    std::cout << it.base() - items.begin() << ' ';

}

现在，假设您要更新{ itemA: 'bla', name: [ {a: 2, b:3, value:'John', lannguages:['pt','en']} ], obj:{ obj2:{ nestedArray : [1,2,3] } } }动作的nestedArray道具，并以UPDATE_ARRAY的形式传递数字，以进行合并：

action.data

只需按正确的顺序使用点差运算符，就可以了！

在减速器中更新嵌套状态

2 个答案: