Ngrx proper approach on displaying success or error messages or redirects after an http request

Question

I have an Ionic 3 App where I use ngrx/store and ngrx/effects for side effect or async actions. Everything works fine but there is one little problem.

When should I call the error or success message after dispatching a action. I know that the effect job is to dispatch another action base on a dispatched action from the component. But where should I put it?

Here is my sample below of my reducer.ts

mport { LOGIN_REQUEST, LOGIN_FAILED, LOGIN_SUCCESS } from './../actions/authenticate';
import { AuthState } from './../store';
import { Action } from '@ngrx/store';
import { PostState } from '../store';

const initialState: AuthState = {
    isAuthenticated: false,
    authenticating: false,
    token: null,
    error: null
}

export function authReducer(state = initialState, action: Action) {
    switch (action.type) {
        case LOGIN_REQUEST:
            return {
                ...state,
                authenticating: true,
                // USERS: (<any>action).data.USERS
            }
        case LOGIN_SUCCESS:
            return {
                ...state,
                authenticating: false,
                isAuthenticated: true,
                token: (<any>action).payload.data.token
            }
        case LOGIN_FAILED:
            return {
                ...state,
                authenticating: false,
                error: (<any>action).payload
            }
        default:
            return state;
    }
}

and in my effects.ts

@Effect()
    authenticate$ = this.actions$.ofType(authActions.LOGIN_REQUEST)
        .pipe(
            switchMap((data: any) => {
                return this.authApi.signIn(data.payload).pipe(
                    map((response: any) => ({ type: authActions.LOGIN_SUCCESS, payload: response })),
                    catchError(error => of({ type: authActions.LOGIN_FAILED, payload: error }))
                )
            })
        )

In my app.module

imports: [
    ...
    StoreModule.forRoot(rootReducer, { metaReducers }),
    EffectsModule.forRoot(effects),
    StoreDevtoolsModule.instrument({
      maxAge: 5
    })
  ],

and finally in my component.ts

ionViewWillEnter() {
    this.store.select<any>('auth').subscribe(state => {
      this.auth = state
      if (state.error) this.displayErrorMessage()
    })
  }



    displayErrorMessage() {
    const toast = this.toastCtrl.create({
      message: 'Error occured',
      duration: 3000,
      position: 'top'
    });

    toast.onDidDismiss(() => {
      console.log('Dismissed toast');
    });

    toast.present();
  }

If you are familiar with redux you knew that you would understand the code above in the reducers and effects. Everything is working fine but I think there is a little problem in my component on when to call a success or error message? Should I call it instead in the effect? But How?

Appreciate if someone could help with code sample. Thanks in advance.

Answer 1

You could inject ActionsSubject into the component and listen for success or failed actions, but I wouldn't recommend this.

Instead also use effects to show notifications, e.g. with an angular material snackbar:

@Effect({ dispatch: false })
error = this.actions.pipe(
 ofType<ServerError>(ActionTypes.ServerError),
 map(({ payload }) => {
   this.snackBar.open(payload.message, 'Close');
 })
)

For more info see Start using ngrx/effects for this