by Gerard Sans | @gerardsans

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Google Developer Expert

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Spoken at 92 events in 25 countries

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Community Leader

900

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Trainer

Master of Ceremonies

Master of Ceremonies

NGXS

Overview

  • Angular Developer Friendly
    • ​​Decorators
    • Dependency Injection
    • Life cycle hooks
  • Minimal Setup
  • Extensible via plugins
  • Community driven

Components

Actions

State

Mutate

Dispatch

Notify

Observables

actions

states

A

A

A

S

S

S

Components

Actions

State

Mutate

Dispatch

Notify

Plugins

Actions

State

Counter

Increment

Decrement

Reset

Total

Components

Actions

State

Mutate

Dispatch

Notify

import { State } from '@ngxs/store';

@State<number>({ 
  name: 'counter', 
  defaults: 0
})
export class CounterState { }
src/app.component.ts

Counter State

app/store/counter.state.ts

Components

Actions

State

Mutate

Dispatch

Notify

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

// const action = new Increment(); 

// { 
//    type: "[Counter] Increment"
// }
src/app.component.ts

Increment Action

app/store/counter.actions.ts
import { State, Action, StateContext } from '@ngxs/store';
import { Increment } from '../store/counter.actions';

@State<number>({ name: 'counter', defaults: 0 })
export class CounterState {
  @Action(Increment)
  Increment(store: StateContext<number>) {
    const counter = store.getState();
    store.setState(counter+1);
  } 
}
src/app.component.ts

Increment Action

app/store/counter.state.ts
export class Reset {
  static readonly type = "[Counter] Reset";
  constructor(public payload: { value: number }) { }
}
// const action = new Reset({ value: 0 });
 
// { 
//   type: "[Counter] Reset", 
//   payload: { 
//     value: 0 
//   } 
// }
src/app.component.ts

Reset Action

app/store/counter.actions.ts
import { State, Action, StateContext } from '@ngxs/store';
import { Reset } from '../store/counter.actions';

@State<number>({ name: 'counter', defaults: 0 })
export class CounterState {
  @Action(Reset)
  Reset(store: StateContext<number>, action: Reset) {
    const counter = store.getState();
    store.setState(action.payload.value);
  }
}
src/app.component.ts

Reset Action

app/store/counter.state.ts

Components

Actions

State

Mutate

Dispatch

Notify

@Component({
  template: `
    <app-counter
      (increment)="increment()" (decrement)="decrement()"
      (reset)="reset()">
    </app-counter>`
})
export class AppComponent  {
  constructor(private store: Store) { }
  increment = () => this.store.dispatch(new Increment());
  decrement = () => this.store.dispatch(new Decrement());
  reset = () => this.store.dispatch(new Reset({ value: 0 }));
}
src/app.component.ts

Dispatching Actions

app/app.component.ts
@Component({
  template: `
    <app-counter [total]="counter|async"></app-counter>`
})
export class AppComponent  {
  @Select(state => state.counter) counter: Observable<number>;
}
src/app.component.ts

Subscribing to the Store

app/app.component.ts
@Component({ 
  selector: 'app-counter',
  template: `
    <div class="total">{{total}}</div>
    <button (click)="increment.emit()">+</button>
    <button (click)="decrement.emit()">-</button>
    <button (click)="reset.emit()">C</button>`,
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class CounterComponent {
  @Input() total: number;
  @Output() increment = new EventEmitter();
  ...
}
src/app.component.ts

Counter

app/counter/counter.component.ts

Plugins

Logger

DevTools

Storage

Forms

WebSockets

Router

import { NgxsModule } from '@ngxs/store';
import { NgxsReduxDevtoolsPluginModule } 
  from '@ngxs/devtools-plugin';
​
@NgModule({
  imports: [
    NgxsModule.forRoot([]),
    NgxsReduxDevtoolsPluginModule.forRoot()
  ]
})
export class AppModule {}
src/app.component.ts

Adding DevTools Plugin

import { NgxsModule } from '@ngxs/store';
import { NgxsFormPluginModule } 
  from '@ngxs/form-plugin';
​
@NgModule({
  imports: [
    NgxsModule.forRoot([]),
    NgxsFormPluginModule.forRoot(),
    NgxsReduxDevtoolsPluginModule.forRoot()
  ]
})
export class AppModule {}
src/app.component.ts

Adding Forms Plugin

​@State({
  name: "app",
  defaults: {
    form: {
      model: undefined,
      dirty: false,
      status: "",
      errors: {}
    }
  }
})
export class AppState {}
src/app.component.ts

Adding initial form state

@Component({
  selector: 'form',
  template: `
    <form ngxsForm="app.form" novalidate
      [formGroup]="form" (ngSubmit)="onSubmit()">
      <input type="text" formControlName="email" />
      <button type="submit">Subscribe</button>
    </form>`
})
export class FormComponent { }
src/app.component.ts

Tracking form changes

import { NgxsModule } from '@ngxs/store';
import { NgxsRouterPluginModule } 
  from '@ngxs/router-plugin';
​
@NgModule({
  imports: [
    NgxsModule.forRoot([]),
    NgxsRouterPluginModule.forRoot()
  ]
})
export class AppModule {}
src/app.component.ts

Adding Router Plugin

Advanced NGXS

Todo App

Selectors

{ 
  todos: [{ id: 1, text: 'todo 1', complete: false }],
  currentFilter: "SHOW_ALL"
}

// Filtered Todos
[{ id: 1, text: 'todo 1', complete: false }]
src/app.component.ts

Example: Todos State Selector

{ 
  todos: [{ id: 1, text: 'todo 1', complete: false }],
  currentFilter: "SHOW_COMPLETED"
}

// Filtered Todos
[]
import { FilterState } from '../filter/filter.state';

@State<Todo[]>({ name: 'todos', defaults: [] })
export class TodosState {
  @Selector([FilterState]) static todos(state, currentFilter) {
    let t = state.slice().reverse();
    switch (currentFilter) {
      case 'SHOW_ACTIVE': return t.filter(t => !t.completed);
      case 'SHOW_COMPLETED': return t.filter(t => t.completed);
      case 'SHOW_ALL':
      default: return t;
    };
  }
}
src/app.component.ts

Selector: Filtered Todos

Comparison

  • v3.1.3 (3 months)
  • 53 contributors
  • Plugins
  • 1K stars
  • v6.0.1 (2 years)
  • 119 contributors
  • CLI integration
  • 3K stars

More

Austin McDaniel

@amcdnl

ngxs.io

Medium

Thanks

NGXS: Redux implemented in 2018

By Gerard Sans

NGXS: Redux implemented in 2018

In this talk, we are going to look into NGXS, a new State Management library released earlier this year. We will introduce its main concepts and cover all the good stuff up to v3.1 release: state/actions life cycle, advanced selectors, snapshots, plugins and more!

  • 1,565
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