ngRx Store - Reducer 返回未定义 - store.select() 未定义

Question

这是我第一次使用 ngRx Store，我实现了我的第一个效果..

什么工作正常：

• 与后端通信
• 正在后端执行操作（删除、添加、获取）
• 有效载荷从效果到达减速器（记录下来以确保）

所以我的问题是我无法从减速器中获取数据。 如果我 select 将数据从存储在我的组件中，我会在组件中获得未定义的数据。 我点击了效果中的数据，数据被明确传递了。 还将数据记录在减速器中 - 它就在那里。 但是当它返回时，它返回未定义。 ReDux Devtools 记录一切正常。 最后但并非最不重要的一点.. state 没有更新，即使是固定值，如 boolean 与 true/false 用于加载。

乐代码：

// 我得到未定义的地方

export class ProfileComponent implements OnInit {

  user: any;
  items$: Observable<Product[]>;
  loading$: Observable<boolean>;
  error$: Observable<Error>;
  newItem: Product = {id: 0, name:""};

  constructor(private keycloakService: KeycloakService, private store: Store<ProductState>, private productService: ProductService) { }

  ngOnInit(): void {
    this.productService.setToken(this.keycloakService.getToken());

    this.user = this.keycloakService.getUsername();

    this.items$ = this.store.select(store => store.list);
    this.loading$ = this.store.select( store => store.loading);
    this.error$ = this.store.select( store => store.error);

    this.store.dispatch(new LoadProduct());

    this.items$.subscribe(val => console.log(val));
    this.loading$.subscribe(val => console.log(val));
    this.error$.subscribe(val => console.log(val));
  }

// 减速器

export type Action = Products.All;

const initialState: ProductState = {
  list: [],
  loading: false,
  error: undefined
}

const newState = (state, newData) => {
  return Object.assign({}, state, newData);
}

export function reducer(state: ProductState = initialState, action: Action) : ProductState{
  console.log(action.type, state);

  switch (action.type) {
    case Products.LOAD_PRODUCT: return { ...state, loading: true};
    case Products.LOAD_PRODUCT_SUCCESS: return newState(state, {list: action.payload, loading: false, error: undefined});
    case Products.LOAD_PRODUCT_FAILURE: return { ...state, error: action.payload, loading: false};
    case Products.ADD_PRODUCT: return { ...state, loading: true};
    case Products.ADD_PRODUCT_SUCCESS: return { ...state, list: action.payload, loading: false};
    case Products.ADD_PRODUCT_FAILURE: return { ...state, error: action.payload, loading: false};
    case Products.REMOVE_PRODUCT: return { ...state, loading: true};
    case Products.REMOVE_PRODUCT_SUCCESS: return { ...state, list: state.list.filter(item => item.id !== action.payload), loading: false};
    case Products.REMOVE_PRODUCT_FAILURE: return { ...state, error: action.payload, loading: false};
    default: return state;
  }

我非常感谢您的帮助:)

Answer 1

您应该使用选择器函数从商店获取数据： https://ngrx.io/guide/store/selectors

为了快速解除阻塞，我敢打赌 state 上未定义.list, .loading, .error state

试试这个来调试：

// see how the whole store looks like
this.store.subscribe(state => console.log({ state }));

对你来说，我认为它与products相关，所以我敢打赌它应该是这样的：

this.items$ = this.store.select(store => store.products.list);
this.loading$ = this.store.select( store => store.products.loading);
this.error$ = this.store.select( store => store.products.error);