@ngxs-labs/dispatch-decorator

---

The distribution for separation of concern between the state management and the view

This package simplifies the dispatching process. It would be best if you didn't care about the Store service injection, as we provide a more declarative way to dispatch events out of the box.

Compatibility with Angular Versions

@ngxs-labs/dispatch-decorator	Angular
4.x	>= 13 < 15
5.x	>= 15

📦 Install

To install the @ngxs-labs/dispatch-decorator, run the following command:

$ npm install @ngxs-labs/dispatch-decorator
# Or if you're using yarn
$ yarn add @ngxs-labs/dispatch-decorator
# Or if you're using pnpm
$ pnpm install @ngxs-labs/dispatch-decorator

🔨 Usage

Import the module into your root application module:

import { NgModule } from '@angular/core';
import { NgxsModule } from '@ngxs/store';
import { NgxsDispatchPluginModule } from '@ngxs-labs/dispatch-decorator';

@NgModule({
  imports: [NgxsModule.forRoot(states), NgxsDispatchPluginModule.forRoot()]
})
export class AppModule {}

Dispatch Decorator

@Dispatch() can be used to decorate methods and properties of your classes. Firstly let's create our state for demonstrating purposes:

import { State, Action, StateContext } from '@ngxs/store';

export class Increment {
  static readonly type = '[Counter] Increment';
}

export class Decrement {
  static readonly type = '[Counter] Decrement';
}

@State<number>({
  name: 'counter',
  defaults: 0
})
export class CounterState {
  @Action(Increment)
  increment(ctx: StateContext<number>) {
    ctx.setState(ctx.getState() + 1);
  }

  @Action(Decrement)
  decrement(ctx: StateContext<number>) {
    ctx.setState(ctx.getState() - 1);
  }
}

We are ready to try the plugin after registering our state in the NgxsModule, given the following component:

import { Component } from '@angular/core';
import { Select } from '@ngxs/store';
import { Dispatch } from '@ngxs-labs/dispatch-decorator';

import { Observable } from 'rxjs';

import { CounterState, Increment, Decrement } from './counter.state';

@Component({
  selector: 'app-root',
  template: `
    <ng-container *ngIf="counter$ | async as counter">
      <h1>{{ counter }}</h1>
    </ng-container>

    <button (click)="increment()">Increment</button>
    <button (click)="decrement()">Decrement</button>
  `
})
export class AppComponent {
  @Select(CounterState) counter$: Observable<number>;

  @Dispatch() increment = () => new Increment();

  @Dispatch() decrement = () => new Decrement();
}

You may mention that we don't have to inject the Store class to dispatch actions. The @Dispatch decorator takes care of delivering actions internally. It unwraps the result of function calls and calls store.dispatch(...).

Dispatch function can be both synchronous and asynchronous, meaning that the @Dispatch decorator can unwrap Promise and Observable. Dispatch functions are called outside of the Angular zone, which means asynchronous tasks won't notify Angular about change detection forced to be run:

export class AppComponent {
  // `ApiService` is defined somewhere
  constructor(private api: ApiService) {}

  @Dispatch()
  async setAppSchema() {
    const version = await this.api.getApiVersion();
    const schema = await this.api.getSchemaForVersion(version);
    return new SetAppSchema(schema);
  }

  // OR using lambda

  @Dispatch() setAppSchema = () =>
    this.api.getApiVersion().pipe(
      mergeMap(version => this.api.getSchemaForVersion(version)),
      map(schema => new SetAppSchema(schema))
    );
}

Note it doesn't if an arrow function or a regular class method is used.

Dispatching Multiple Actions

@Dispatch function can return arrays of actions:

export class AppComponent {
  @Dispatch() setLanguageAndNavigateHome = (language: string) => [
    new SetLanguage(language),
    new Navigate('/')
  ];
}

Canceling

@Dispatch functions can cancel currently running actions if they're called again in the middle of running actions. This is useful for canceling previous requests like in a typeahead. Given the following example:

@Component({ ... })
export class NovelsComponent {
  @Dispatch() searchNovels = (query: string) =>
    this.novelsService.getNovels(query).pipe(map(novels => new SetNovels(novels)));

  constructor(private novelsService: NovelsService) {}
}

We have to provide the cancelUncompleted option if we'd want to cancel previously uncompleted getNovels action:

@Component({ ... })
export class NovelsComponent {
  @Dispatch({ cancelUncompleted: true }) searchNovels = (query: string) =>
    this.novelsService.getNovels(query).pipe(map(novels => new SetNovels(novels)));

  constructor(private novelsService: NovelsService) {}
}