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@ngrx/store

RxJS powered state management for Angular applications, inspired by Redux

@ngrx/store is a controlled state container designed to help write performant, consistent applications on top of Angular. Core tenets:

• State is a single immutable data structure
• Actions describe state changes
• Pure functions called reducers take the previous state and the next action to compute the new state
• State accessed with the Store, an observable of state and an observer of actions

These core principles enable building components that can use the OnPush change detection strategy giving you intelligent, performant change detection throughout your application.

Installation

Install @ngrx/core and @ngrx/store from npm:

npm install @ngrx/core @ngrx/store@2.2.3 --save

Optional packages:

• @ngrx/store-devtools instruments your store letting you use a powerful time-travelling debugger.
• @ngrx/router-store keeps the state of @angular/router in your store
• @ngrx/effects isolates side effects from your UI by expressing side effects as sources of actions

Examples

• Official @ngrx/example-app is an officially maintained example application showcasing best practices for @ngrx projects, including @ngrx/store and @ngrx/effects
• angular-webpack2-starter is a complete Webpack 2 starter with built-in support for @ngrx. Includes Ahead-of-Time (AOT) compilation, hot module reloading (HMR), devtools, and server-side rendering.

Introduction

• Reactive Angular 2 with ngrx (video)
• Comprehensive Introduction to @ngrx/store
• @ngrx/store in 10 minutes (video)
• Build Redux Style Applications with Angular2, RxJS, and ngrx/store (video)

Setup

Create a reducer function for each data type you have in your application. The combination of these reducers will make up your application state:

// counter.ts
import { ActionReducer, Action } from '@ngrx/store';

export const INCREMENT = 'INCREMENT';
export const DECREMENT = 'DECREMENT';
export const RESET = 'RESET';

export function counterReducer(state: number = 0, action: Action) {
	switch (action.type) {
		case INCREMENT:
			return state + 1;

		case DECREMENT:
			return state - 1;

		case RESET:
			return 0;

		default:
			return state;
	}
}

In your app's main module, import those reducers and use the StoreModule.provideStore(reducers) function to provide them to Angular's injector:

import { NgModule } from '@angular/core'
import { StoreModule } from '@ngrx/store';
import { counterReducer } from './counter';

@NgModule({
  imports: [
    BrowserModule,
    StoreModule.provideStore({ counter: counterReducer })
  ]
})
export class AppModule {}

You can then inject the Store service into your components and services. Use store.select to select slice(s) of state:

import { Store } from '@ngrx/store';
import { INCREMENT, DECREMENT, RESET } from './counter';

interface AppState {
  counter: number;
}

@Component({
	selector: 'my-app',
	template: `
		<button (click)="increment()">Increment</button>
		<div>Current Count: {{ counter | async }}</div>
		<button (click)="decrement()">Decrement</button>

		<button (click)="reset()">Reset Counter</button>
	`
})
class MyAppComponent {
	counter: Observable<number>;

	constructor(private store: Store<AppState>){
		this.counter = store.select('counter');
	}

	increment(){
		this.store.dispatch({ type: INCREMENT });
	}

	decrement(){
		this.store.dispatch({ type: DECREMENT });
	}

	reset(){
		this.store.dispatch({ type: RESET });
	}
}

Contributing

Please read contributing guidelines here.