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[Angular 2] Passing Observables into Components with Async Pipe

时间:2016-04-27 06:53:08      阅读:224      评论:0      收藏:0      [点我收藏+]

The components inside of your container components can easily accept Observables. You simply define your custom @Input then use the Async pipe when you pass the Observable in. This lesson walks you through the process of passing an Observable into a Component.

 

The idea is Your smart component prepares the data and use ‘async pipe‘ to pass into the dumb component to display. So the dump component has no idea about Observable. Just need to display the data.

 

// clock.ts


import {Component, Input} from angular2/core;
@Component({
    selector: clock,
    template: `<h3>{{time | date:yMMMMEEEEdjms}}</h3>`
})

export class ClockComponent{
    @Input() time;
    constructor(){
        
    }
}

 

// app.ts

/**
 * Created by wanzhen on 26.4.2016.
 */
import {Component} from angular2/core;
import {Observable} from rxjs/Observable;
import rxjs/add/observable/interval;
import rxjs/add/operator/map;
import rxjs/add/observable/merge;
import rxjs/add/operator/startWith;
import rxjs/add/operator/scan;
import rxjs/add/operator/mapTo;
import {Subject} from "rxjs/Subject";
import {Store} from @ngrx/store;
import {SECOND, HOUR} from ./reducer;
import {ClockComponent} from ./clock;

@Component({
    selector: app,
    directives: [ClockComponent],
    template: `
        <input #inputNum type="number" value="0">
        <button (click)="click$.next(inputNum.value)">Update</button>
        <clock [time]="time | async"></clock> 
        `
})
export class App {
    click$ = new Subject()
            .map( (number) => ({type: HOUR, payload: parseInt(number)}));

    seconds$ = Observable.interval(1000)
        .mapTo({type: SECOND, payload: 1});

    time;

    constructor(store:Store) {
        this.time = store.select(clock);


        Observable.merge(
            this.click$,
            this.seconds$
            )
            .subscribe(store.dispatch.bind(store))
    }
}

Here using ‘store.dipatch.bind(store)‘ instead of ‘function(action){store.dispatch(action)}‘.

 

// reducer.ts

export const SECOND = "SECOND";
export const HOUR = "HOUR";

export const clock = (state = new Date(), {type, payload})=> {
    const date = new Date(state.getTime());
    switch(type){
        case SECOND:
            date.setSeconds(date.getSeconds() + payload);
            return date;

        case HOUR:
            date.setHours(date.getHours() + payload);
            return date;

    }

    return state;
};

 

// main.ts

import {bootstrap} from angular2/platform/browser;
import {App} from ./app;
import {provideStore} from @ngrx/store;
import {clock} from ./reducer;

bootstrap(App, [
    provideStore({clock})
]).then(
    ()=> console.log(App running...),
    err=> console.log(err)
);

/*
*  1. Create a reducer
*  2. Use provideStore({reducer_name}) to provide store
*  3. Use store.select(‘reducer_name‘) to get store in Observable type
*  4. Apply logic to dispatch the action
* */

 

[Angular 2] Passing Observables into Components with Async Pipe

原文:http://www.cnblogs.com/Answer1215/p/5437366.html

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