在React Redux reducer中更新数组对象

Question

这应该很简单,但我找不到我想要的简单答案.我有一个减速器:

const posts = (state = null, action) => {
  switch(action.type){
    case "PUBLISH_POST":
        return state;
    case "UNPUBLISH_POST":
        return state;
    default:
        return postList;
  }
}

我有一个帖子列表ID's和a status.我正在发送我的帖子ID但是无法找出简单地将status已经点击的项目从0 更新为1 的逻辑.我发现了很多半解决方案,但它们看起来都很冗长和丑陋 - 在这种情况下实现它的最短/最佳方式是什么？

示例数据:

{
    id:1,
    user:"Bob Smith",
    content:"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quisque vulputate mauris vitae diam euismod convallis. Donec dui est, suscipit at dui vitae, sagittis efficitur turpis. ",
    status:1 
}

Answer 1

假设你action是这样的:

{
  type: 'UNPUBLISH_POST',
  payload: {
    id: 1,
    user: 'Bob Smith',
    content: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quisque vulputate mauris vitae diam euismod convallis. Donec dui est, suscipit at dui vitae, sagittis efficitur turpis. ',
    status: 1
  }
}

只需使用扩展运算符:

const posts = (state = null, action) => {
  switch(action.type){
    case "PUBLISH_POST":
    case "UNPUBLISH_POST":
        const index = this.state.findIndex(post => post.id === action.payload.id)

        return [
           ...state.slice(0, index), // everything before current post
           {
              ...state[index],
              status: action.type === 'PUBLISH_POST' ? 1 : 0,
           },
           ...state.slice(index + 1), // everything after current post
        ]
    default:
        return postList;
  }
}

Answer 2

A more general solution, especially if state contains other data besides your posts array:

const posts = (state = null, action) => {
  const post = state.posts.find(p => p.id === action.payload.id);
  switch(action.type) {
    case "PUBLISH_POST":
      return { ...state, posts: [ ...state.posts.filter(p => p !== post), { ...post, status: 1 } ] };
    case "UNPUBLISH_POST":
      return { ...state, posts: [ ...state.posts.filter(p => p !== post), { ...post, status: 0 } ] };
    default:
      return state;
  }
}