NGRX原理

原理

  • component产生action
  • action触发effect，业务处理数据
  • store中存储state、reducer
  • reducer产生新的state
  • state修改，更新component

安装

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npm install @ngrx/store

Counter示例

定义action

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// .app/counter.action.ts
import {createAction} from '@ngrx/store';

export const increment = createAction('[Counter Component] increment');
export const decrement = createAction('[Counter Component] decrement');
export const reset = createAction('[Counter Component] reset');

定义reducer

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import {createReducer, on} from '@ngrx/store';
import {increment, decrement, reset} from './counter.action.ts';

export const initialState = 0;
const _counterReducer = createReducer(initialState,
	on(increment, state=>state+1),
    on(decrement, state=>state-1),
    on(reset, state=>0))
export function counterReducer(state: any, action: any){
    return _counterReducer(state, action);
}

注册state

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// app.module.ts
imports: [
    BrowserModule,
    StoreModule.forRoot({count: counterReducer})
]

定义Counter组件

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<!--counter.component.html-->
<div>
    {{counterNumber$ | async}}
    <button (click)="increment()">incre</button>
    <button (click)="decrement()">decre</button>
    <button (click)="reset()">reset</button>
</div>
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// counter.component.ts
import { Component } from '@angular/core';
import { select, Store } from '@ngrx/store';
import { Observable } from 'rxjs';
import { increment, decrement, reset } from 'src/app/counter.actions';

@Component({
  selector: 'app-counter',
  templateUrl: './counter.component.html',
  styleUrls: ['./counter.component.css']
})
export class CounterComponent {
  counterNumber$: Observable<number>;
  constructor(private store: Store<{count: number}>){
    this.counterNumber$ = store.pipe(select('count'));
  }
  increment(){
    this.store.dispatch(increment());
  }
  decrement(){
    this.store.dispatch(decrement());
  }
  reset(){
    this.store.dispatch(reset());
  }
}