当另一个动作成功时调度一个动作

Question

我是 angular 和 redux 世界的新手。我想我有一个常见问题，但我找不到正确的答案，或者我只需要一个有用的提示。我在我的应用程序中使用 ngrx，我想更新用户的一些基本数据。然后我想重新加载一个用户的数据。

简而言之 (1) 更新用户数据 (2)加载用户数据 (3) 在前端可视化

如果我先调度更新然后加载数据，它并不总是有效。我了解到调度程序是异步运行的，因此不能说哪个先完成。

我的想法。我将不得不 (1) 使用承诺更新用户数据，然后 (2) 加载和显示用户数据。还是我错了？

感谢您的帮助

这是我的代码

currenUser.effects.ts

[...]

@Injectable()
export class CurrentUserEffects {

  constructor(
    private actions$: Actions,
    private currentUserService: CurrentUserService
    ) {}

    @Effect()
    loadCurrentUser$ = this.actions$.pipe(
      ofType(ActionTypes.LoadCurrentUser),
      mergeMap((action: LoadCurrentUserAction) =>
        this.currentUserService
          .getCurrentUserNew()
          .pipe(
              map(
                (currentUser: CurrentUserNew) => new LoadCurrentUserActionFinished(currentUser)
              )
          )
      )
    );

    @Effect()
    updateCurrentUser$ = this.actions$.pipe(
      ofType(ActionTypes.UpdateCurrentUser),
      switchMap((action: UpdateCurrentUserAction) =>

        // update
        this.currentUserService
          .updateCurrentUser(action.oldCurrentuser, action.newCurrentUser)
          .then(
            response => {
                return new UpdateCurrentUserActionFinished(response);
            }
          )

        // here relaod data?

      )
    );
}

currentUser.actions.ts

import { CurrentUserNew } from './../../models/currentUserNew';
import { Action } from '@ngrx/store';

export enum ActionTypes {
  LoadCurrentUser = '[CurrentUser] Load current user',
  LoadCurrentUserFinished = '[CurrentUser] Load current user finished',

  UpdateCurrentUser = '[CurrentUser] Update current user',
  UpdateCurrentUserFinished = '[CurrentUser] Update current user finished',
}

export class LoadCurrentUserAction implements Action {
  readonly type = ActionTypes.LoadCurrentUser;
}

export class LoadCurrentUserActionFinished implements Action {
  readonly type = ActionTypes.LoadCurrentUserFinished;
  constructor(public payload: CurrentUserNew) {}
}

export class UpdateCurrentUserAction implements Action {
  readonly type = ActionTypes.UpdateCurrentUser;
  constructor(
    public oldCurrentuser: CurrentUserNew,
    public newCurrentUser: CurrentUserNew
     ) {}
}

export class UpdateCurrentUserActionFinished implements Action {
  readonly type = ActionTypes.UpdateCurrentUserFinished;
  constructor(public payload: boolean) {}
}

export type CurrentUserActions =
  | LoadCurrentUserAction
  | LoadCurrentUserActionFinished
  | UpdateCurrentUserAction
  | UpdateCurrentUserActionFinished;

currentUser.reducer.ts

import { CurrentUserNew } from './../../models/currentUserNew';
import { CurrentUserActions, ActionTypes } from './currentUser.actions';

export interface ReducerCurrentUserState{
  currentUser: CurrentUserNew;
  isUpdated: boolean;
}

export const initialState: ReducerCurrentUserState = {
  currentUser: null,
  isUpdated: false
};

export function currentUserReducer(
  state = initialState,
  action: CurrentUserActions
): ReducerCurrentUserState {


  switch (action.type) {
    case ActionTypes.LoadCurrentUser: {
      return {
        ...state,
      };
    }

    case ActionTypes.LoadCurrentUserFinished: {
      return {
        ...state,
        currentUser: action.payload,
      };
    }

    case ActionTypes.UpdateCurrentUser: {
      return {
        ...state,
      };
    }

    case ActionTypes.UpdateCurrentUserFinished: {
      return {
        ...state,
        isUpdated: action.payload,
      };
    }

    default:
      return state;
  }

}

currentUser.selectors.ts

import { ReducerCurrentUserState, currentUserReducer } from './currentUser.reducer';
import { ActionReducerMap, createFeatureSelector, createSelector } from '@ngrx/store';

export const currentUserFeatureStateName = 'currentUserFeature';

export interface CurrentUserState {
  currentUser: ReducerCurrentUserState;
}

export const currentUserReducers: ActionReducerMap<CurrentUserState> = {
  currentUser: currentUserReducer,
};

// extract the main property from the state object
export const getCurrentUserFeatureState = createFeatureSelector<CurrentUserState>(
  currentUserFeatureStateName
);

export const getCurrentUser = createSelector(
  getCurrentUserFeatureState,
  (state: CurrentUserState) => state.currentUser.currentUser
)

export const isCurrentUserUpdatedSuccessful = createSelector(
  getCurrentUserFeatureState,
  (state: CurrentUserState) => state.currentUser.isUpdated
)

Answer 1

起初我尝试在一个效果中调用两个动作

    @Effect()
    updateAndLoadCurrentUser$ = this.actions$.pipe(
        ofType(ActionTypes.UpdateAndLoadCurrentUser),
        switchMap((action: UpdateCurrentUserAction) =>
            of(
                new UpdateCurrentUserAction(action.oldCurrentuser, action.newCurrentUser),
                new LoadCurrentUserAction(),
                new UpdateAndLoadCurrentUserActionFinished()
            )
        )
    );

这里是异步动作值得我回答的问题。

我的解决方案：

实际上我的解决方案是调用一个动作。该操作向后端调用 http 请求，后端为我提供了正确的对象。

但是，我现在对如何一个接一个地触发两个动作感兴趣。不幸的是我还没有找到解决方案

当另一个动作成功时调度一个动作

Dispatch a Action when the other action is successful

redux

ngrx

ngrx-effects

angular

ngrx-store