[Angular2] @Ngrx/store and @Ngrx/effects learning note

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Just sharing the learning experience related to @ngrx/store and @ngrx/effects.

In my personal opinion, I fell there are tow different types of coding style by using 

1. @ngrx/store only

2. @ngrx/store + @ngrx/effects

So How we do with only ngrx/store?

Controller: 

 deleteItem(item: Item) {
    this.subs[‘deleteItem‘] = this.itemsService.deleteItem(item)
      .subscribe(
        (res) => {
          console.log("Delete Item success", JSON.stringify(res, null, 2))
          this.resetItem();
        },
        (err) => alert("error")
      );
  }

Service:

export class ItemsService {
  items$: Observable<Item[]> = this.store.select(‘items‘);

  constructor(
    private http: Http,
    private store: Store<AppStore>,
    private actions: ItemsActions
  ) {}

  deleteItem(item: Item) {
    return this.http.delete(`${BASE_URL}${item.id}`)
      .do(action => this.store.dispatch({ type: DELETE_ITEM, payload: item }));
  }

Reducer:

    case DELETE_ITEM:
      return state.filter(item => {
        return item[comparator] !== action.payload[comparator];
      });

As you can see, the working flow is like that:

1. Form controller we call the Service to delete the item

2. Service do the http call to remove the item

3. Then we have ‘.do()‘ method to create side effect, call dispatch 

4. Since the return from Service is Observable, we subscribe form the controller.

5. Inside successfully handler, we can do any other ui side effect.

ngrx/store + ngrx/effects:

Controller: 

  deleteWidget(widget: Widget) {
    this.store.dispatch({type: DELETE_WIDGET, payload: widget});
  }

Service:

  deleteWidget(widget: Widget) {
    return this.http.delete(`${BASE_URL}${widget.id}`);
  }

Effect:

  @Effect() delete$: Observable<Action> = this.actions$
    .ofType(DELETE_WIDGET)
    .map(action => action.payload)
    .switchMap((widget)=>{
      return this.widgetsService.deleteWidget(widget)
                .map(success => console.log("success"))
                .catch(() => of("error")) // catch expect to get an observable back
    });

Reducer:

    case DELETE_WIDGET:
      return state.filter(widget => {
        return widget[comparator] !== action.payload[comparator];
      });

So the work flow for ngrx/store + ngrx/effects:

1. From the controller, we just dispatch the action.

2. Effect listening the actions that dispatched, and trigger ‘ofType‘ the same is dispatched action from controller.

3. Inside effect, we call service to delete the widget.

4. If http request is success, we actually can dispatch another UI action that will do the UI rendering.

5. If http reuqest is faild, we catch it and you actually can dispatch another UI action that will show the error in UI.

Github

Summary:

By using only ngrx/store, we are still using the coding style we get used to, like controller talking to the service, after service done its job, return back to controller, let controller do whatever necessary.

By using ngrx/store + ngrx/effects, we are actullay walking into RxJS + Redux world, everything goes reactive, everything should have a reducer even it is UI rendering stuff.

I am not sure which way is better. My point is I am using Redux partten, take advantage of RxJS to help me handle state management esailer. But I don‘t know to overkill, everything conver to Observable and reducers style is way to far from the starting point -- state management.

[Angular2] @Ngrx/store and @Ngrx/effects learning note

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原文地址：http://www.cnblogs.com/Answer1215/p/6053021.html