Redux - 如何在reducer中添加数组的条目 [英] Redux - How to add entry to array in reducer

问题描述

我坚持这一点，我无法进步 - 我想解决方案很简单，但我无法弄清楚。我正在尝试在reducer中添加条目，因此数据将会显示：

  state = {
 entryId：{
 entryName：[something，something2，something3/ *等等... * /] 
 } 
}; 
  

到目前为止，这是我最接近的，但是，而不是添加新的唯一条目，它正在替换已经存储的那个。此外，我需要能够将此项目添加到空状态，其中entryId，entryName不存在以避免错误：

  switch（type）{
 case ADD_ENTRY：
 return {
 ... state，
 [entryId]：{
 ...状态[entryId]，
 [entryName]：{
 [uniqueEntry]：true 
} 
} 
}; 
} 
  

任何想法我在做错什么？

解决方案

如果你想添加一个元素到 entryName 数组的末尾，你应该是做：

  return {
 ...状态
 [entryId]：{
 ... state [entryId]，
 [entryName]：[
 ... state [entryId] [entryName]，
 uniqueEntry 
] 
} 
}; 
  

ES6传播与数组的工作原理如下：

< pre class =lang-js prettyprint-override> const array1 = [1，2，3];
const array2 = [4，5，6];
const 8 = 8;

const newArray = ['stuff'，... array1，'things'，... array2，... [7，8]，9];
console.log（newArray）; // [stuff，1，2，3，things，4，5，6，7，8，9]


查看这个要点，其中有一个非常类似于你正在做的事情的例子

我发现这组示例也非常有帮助。这里有很多好东西：

https：// github .com / sebarkbage / ecmascript-rest-spread

更新：

如果 entryName 被初始化为 undefined 像你在评论中说的那样，你可以这样做：

  return {
 ... state，
 [entryId]：{
 ... state [ entryId]，
 [entryName]：[
 ... state [entryId] [entryName] || []，
 uniqueEntry 
] 
} 
}; 
  

我认为这是一个非常好的例子，它使用React / redux大量的嵌套数据结构。 FWIW，多次推荐我尽可能地平坦化你的状态。

I stuck with this bit and I can't progress - I guess solution is simple but I can't figure out. I'm trying to add entry in reducer so data in in would look something this:

state = {
  entryId: {
    entryName: ["something", "something2", "something3" /* and so on... */]
  }
};

So far this is the closest I get, but, instead of adding new unique entry, it is replacing the one that is stored already. Also I need to be able to add this item to empty state where entryId, entryName doesn't exist yet to avoid error:

switch(type) {
  case ADD_ENTRY:
    return {
      ...state,
      [entryId]: {
        ...state[entryId],
        [entryName]: {
          [uniqueEntry]: true
        }
      }
    };
}

Any idea what I'm doing wrong?

解决方案

If you're trying to add an element to the end of the entryName array you should be doing:

return {
  ...state,
  [entryId]: {
    ...state[entryId],
    [entryName]: [
      ...state[entryId][entryName],
      uniqueEntry
    ]
  }
};

ES6 spread with arrays works like this:

const array1 = [1, 2, 3];
const array2 = [4, 5, 6];
const eight = 8;

const newArray = ['stuff', ...array1, 'things', ...array2, ...[7, eight], 9];
console.log(newArray); // ["stuff", 1, 2, 3, "things", 4, 5, 6, 7, 8, 9]

Check out this gist which has an example of something very similar to what you're doing.

I found this set of examples extremely helpful as well. A lot of great stuff in here:

https://github.com/sebmarkbage/ecmascript-rest-spread

Update:

If entryName is initialized to undefined like you say in your comment, you could do this:

return {
  ...state,
  [entryId]: {
    ...state[entryId],
    [entryName]: [
      ...state[entryId][entryName] || [],
      uniqueEntry
    ]
  }
};

I think this is a pretty great example of how painful it can be working with React/redux using a heavily nested data structure. FWIW, it's been recommended to me many times to flatten your state as much as possible.

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