redux - 你可以使用 combineReducers 来组合深度状态 reducer 吗？

Question

Redux 文档建议使用 normalizr像这样设计状态的形状:

{
  entities: {
    cards: {
      42: {
        id: 42,
        text: 'Hello',
        category: 2
      },
      43: {
        id: 53,
        text: 'There?',
        category: 1
      },
    }
    categories: {
      1: {
        id: 1,
        name: 'Questions'
      }
      2: {
        id: 2,
        name: 'Greetings'
      },
    }
  },
  filter: 'SHOW_ALL',
  allCardsList: {
    isFetching: false,
    items: [ 42, 43 ]
  },
}

自然，这会分成三个可组合的 reducer ( filter 、 allThingsList 和 entities )，但在我看来，我想为 entities.cards 编写单独的 reducer 和 entities.categories .

有没有办法将实体管理拆分为允许组合的子 reducer :

let rootReducer = combineReducers({
   entities: {
      things,
      categories
   },
   filter,
   allCardsList
});

保留 cards 有什么好处吗？和 categories在 entities ，而不是保持在根级别(这将允许使用 combineReducers 进行组合)？

{
  cards: { ... },
  categories: { ... },
  filter: 'SHOW_ALL',
  allCardsList: { ... }
}

Answer 1

Is there a way to split management of entities into subreducers that would allow composition like this?

当然! combineReducers()只是给你一个 reducer ，所以你可以多次使用它:

let rootReducer = combineReducers({
   entities: combineReducers({
      things,
      categories
   }),
   filter,
   allCardsList
});

shopping-cart example in Redux repo演示了这种方法。

Are there any advantages to keeping the cards and categories in entities, instead of keeping on the root level?

这取决于你，但我发现你建议的结构更容易使用。将所有实体分组在一个键下确实更容易理解，并且可以使用 combineReducers()正如我上面展示的那样。