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

Question

這是我第一次使用 ngRx Store，我實現了我的第一個效果..

什么工作正常：

• 與后端通信
• 正在后端執行操作（刪除、添加、獲取）
• 有效載荷從效果到達減速器（記錄下來以確保）

所以我的問題是我無法從減速器中獲取數據。 如果我 select 將數據從存儲在我的組件中，我會在組件中獲得未定義的數據。 我點擊了效果中的數據，數據被明確傳遞了。 還將數據記錄在減速器中 - 它就在那里。 但是當它返回時，它返回未定義。 ReDux Devtools 記錄一切正常。 最后但並非最不重要的一點.. state 沒有更新，即使是固定值，如 boolean 與 true/false 用於加載。

樂代碼：

// 我得到未定義的地方

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));
  }

// 減速器

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;
  }

我非常感謝您的幫助:)

Answer 1

您應該使用選擇器函數從商店獲取數據： https://ngrx.io/guide/store/selectors

為了快速解除阻塞，我敢打賭 state 上未定義.list, .loading, .error state

試試這個來調試：

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

對你來說，我認為它與products相關，所以我敢打賭它應該是這樣的：

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);