从特征状态 ngrx 更新根状态

Question

我有一个使用 ngrx 显示博客的应用

主根状态如下

import { Blog } from '../models/blog';

export interface AppState {
  readonly loaded: boolean;
  readonly blogs: {[key:number]:Blog}
}

export const initialState:AppState = {
  loaded: false,
   blogs: {}
}

我还设置了一个功能模块来管理博客

StoreModule.forFeature('crudBlog', reducers)

我现在想知道的是；当我想更新、删除等博客时，如何从功能缩减文件访问我的商店的 AppState（根状态）

所以我可以做这样的事情；

function handleBlogUpdatedAction(state, action){
    const index = action.payload.index;
    const newState = Object.assign({}, rootState);
    newState[index] = action.payload.blog
return newState;
}

或者有没有更好的方法？

Answer 1

ngrx 状态被认为是不可变的，您通过分配newState[index] = action.payload.blog 来更改状态。

例如，这就是你的 reducer 的样子：

export function reducer(
  state = initialState,
  action
) : BlogState {
    switch (action.type) {
        case UPDATED_BLOG_SUCCESS: {
            const blog = action.payload;
            const entites = {
                ...state.entities,
                [blog.id]: blog
            };

            // below is how your new state is returned using the spread operator
            return {
                ...state,
                entities
            };
        }
    }
}

initialState 是：

export interface BlogState {
    entities: { [id: number]: Blog };
    loaded: boolean;
    loading: boolean;
}

export const initialState : BlogState = {
  entities: {},
  loaded: false,
  loading: false,
};