@ngrx/effects
Advanced tools
@ngrx/effects is a library for managing side effects in Angular applications using the Redux pattern. It allows you to isolate side effects from your components and services, making your code more predictable and easier to test.
Handling Side Effects
This code demonstrates how to handle side effects using @ngrx/effects. The `loadItems$` effect listens for the `loadItems` action, calls a service to fetch data, and then dispatches either a success or failure action based on the result.
import { Injectable } from '@angular/core';
import { Actions, createEffect, ofType } from '@ngrx/effects';
import { of } from 'rxjs';
import { catchError, map, mergeMap } from 'rxjs/operators';
import { MyService } from './my-service';
import * as MyActions from './my-actions';
@Injectable()
export class MyEffects {
loadItems$ = createEffect(() => this.actions$.pipe(
ofType(MyActions.loadItems),
mergeMap(() => this.myService.getAll().pipe(
map(items => MyActions.loadItemsSuccess({ items })),
catchError(() => of(MyActions.loadItemsFailure()))
))
));
constructor(
private actions$: Actions,
private myService: MyService
) {}
}Combining Multiple Effects
This code demonstrates how to combine multiple effects in a single class. The `loadItems$` effect handles loading items, while the `updateItem$` effect handles updating an item. Both effects listen for their respective actions and call the appropriate service methods.
import { Injectable } from '@angular/core';
import { Actions, createEffect, ofType } from '@ngrx/effects';
import { of } from 'rxjs';
import { catchError, map, mergeMap } from 'rxjs/operators';
import { MyService } from './my-service';
import * as MyActions from './my-actions';
@Injectable()
export class MyEffects {
loadItems$ = createEffect(() => this.actions$.pipe(
ofType(MyActions.loadItems),
mergeMap(() => this.myService.getAll().pipe(
map(items => MyActions.loadItemsSuccess({ items })),
catchError(() => of(MyActions.loadItemsFailure()))
))
));
updateItem$ = createEffect(() => this.actions$.pipe(
ofType(MyActions.updateItem),
mergeMap(action => this.myService.update(action.item).pipe(
map(() => MyActions.updateItemSuccess({ item: action.item })),
catchError(() => of(MyActions.updateItemFailure()))
))
));
constructor(
private actions$: Actions,
private myService: MyService
) {}
}Error Handling
This code demonstrates how to handle errors in effects. The `loadItems$` effect catches any errors that occur during the service call and dispatches a `loadItemsFailure` action with the error information.
import { Injectable } from '@angular/core';
import { Actions, createEffect, ofType } from '@ngrx/effects';
import { of } from 'rxjs';
import { catchError, map, mergeMap } from 'rxjs/operators';
import { MyService } from './my-service';
import * as MyActions from './my-actions';
@Injectable()
export class MyEffects {
loadItems$ = createEffect(() => this.actions$.pipe(
ofType(MyActions.loadItems),
mergeMap(() => this.myService.getAll().pipe(
map(items => MyActions.loadItemsSuccess({ items })),
catchError(error => of(MyActions.loadItemsFailure({ error })))
))
));
constructor(
private actions$: Actions,
private myService: MyService
) {}
}redux-saga is a library that aims to make side effects (e.g., asynchronous actions like data fetching) easier and more manageable in Redux applications. It uses generator functions to handle side effects, which can make the code more readable and easier to test compared to @ngrx/effects.
redux-thunk is a middleware that allows you to write action creators that return a function instead of an action. This function can then perform asynchronous dispatches. While simpler than @ngrx/effects, it can become harder to manage as the complexity of side effects grows.
MobX is a state management library that makes it simple to connect the reactive data of your application with the UI. Unlike @ngrx/effects, MobX uses observables to manage state and side effects, which can be more intuitive for some developers.
The sources for this package are in the main NgRx repo. Please file issues and pull requests against that repo.
License: MIT
8.0.0-beta.0 (2019-04-17)
BEFORE:
@NgModule({
imports: [StoreRouterConnectingModule],
})
export class AppModule {}
AFTER:
@NgModule({
imports: [StoreRouterConnectingModule.forRoot()],
})
export class AppModule {}
BEFORE:
const getTodosById = createSelector((state: TodoAppSchema, id: number) => state.todos.find((p) => p.id === id));
AFTER:
const getTodosById = createSelector(
(state: TodoAppSchema) => state.todos,
(todos: Todo[], id: number) => todos.find((p) => p.id === id)
);
actionsWhitelist is renamed to actionsSafelist
actionsBlacklist is renamed to actionsBlocklistBEFORE:
StoreDevtoolsModule.instrument({
actionsWhitelist: ['...'],
actionsBlacklist: ['...'],
});
AFTER:
StoreDevtoolsModule.instrument({
actionsSafelist: ['...'],
actionsBlocklist: ['...'],
});
<a name="7.4.0"></a>
FAQs
Side effect model for @ngrx/store
The npm package @ngrx/effects receives a total of 0 weekly downloads. As such, @ngrx/effects popularity was classified as not popular.
We found that @ngrx/effects demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 4 open source maintainers collaborating on the project.
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