我正试图为我的Angular 2应用程序创建一个"很久以前"的管道。
它应该将日期转换为字符串,例如"5分钟前"或"60秒前"。到目前为止,它运行得很好,但在第一次计算后不会更新。例如,如果给定日期是5秒前,则显示"5秒前",但此后不会更改。
我已经尝试过将管道的"纯"值设置为false,但这没有帮助。
这是我的代码:
import {Pipe, PipeTransform} from 'angular2/core';
@Pipe({
name: 'messageTime',
pure: false
})
export class MessageTimePipe implements PipeTransform {
transform(value: Date, []): string {
var result: string;
// current time
let now = new Date().getTime();
// time since message was sent in seconds
let delta = (now - value.getTime()) / 1000;
// format string
if (delta < 10) {
result = 'jetzt';
} else if (delta < 60) { // sent in last minute
result = 'vor ' + Math.floor(delta) + ' Sekunden';
} else if (delta < 3600) { // sent in last hour
result = 'vor ' + Math.floor(delta / 60) + ' Minuten';
} else if (delta < 86400) { // sent on last day
result = 'vor ' + Math.floor(delta / 3600) + ' Stunden';
} else { // sent more than one day ago
result = 'vor ' + Math.floor(delta / 86400) + ' Tagen';
}
return result;
}
}
我使用的过滤器是这样的:
TypeScript:
import {Component, Input} from 'angular2/core';
import {MessageTimePipe} from '../../pipes/message-time.pipe';
@Component({
selector: 'message-item',
pipes: [MessageTimePipe],
templateUrl: 'build/components/message-item/message-item.component.html'
})
export class MessageItemComponent {
@Input()
message: JSON;
date: Date;
ngOnInit() {
this.date = new Date(2016, 3, 16, 12, 49, 10);
}
}
HTML:
<p class="time">
{{ date | messageTime }}
</p>
以下库在英语中起着同等的作用,可以分叉以更改语言或支持不同的语言:
https://www.npmjs.com/package/time-ago-pipe
npm install time-ago-pipe --save
然后在@NgModule中,你想在中使用它
import {TimeAgoPipe} from 'time-ago-pipe'
@NgModule({
imports: [... etc ...],
declarations: [AppComponent, ...etc..., TimeAgoPipe],
bootstrap: [AppComponent]
})
在模板中:
<span>{{your_date | timeAgo}}</span>
终于开始工作了,这很有挑战性,需要调整间隔:)
import {Pipe, ChangeDetectorRef} from 'angular2/core';
import {Observable} from 'rxjs/Observable';
import {AsyncPipe} from 'angular2/common';
@Pipe({
name: 'messageTime',
pure: false
})
export class MessageTimePipe extends AsyncPipe
{
value:Date;
timer:Observable<string>;
constructor(ref:ChangeDetectorRef)
{
super(ref);
}
transform(obj:any, args?:any[]):any
{
if (obj instanceof Date)
{
this.value = obj;
if(!this.timer)
{
this.timer = this.getObservable();
}
return super.transform(this.timer, args);
}
return super.transform(obj, args);
}
private getObservable()
{
return Observable.interval(1000).startWith(0).map(()=>
{
var result:string;
// current time
let now = new Date().getTime();
// time since message was sent in seconds
let delta = (now - this.value.getTime()) / 1000;
// format string
if (delta < 10)
{
result = 'jetzt';
}
else if (delta < 60)
{ // sent in last minute
result = 'vor ' + Math.floor(delta) + ' Sekunden';
}
else if (delta < 3600)
{ // sent in last hour
result = 'vor ' + Math.floor(delta / 60) + ' Minuten';
}
else if (delta < 86400)
{ // sent on last day
result = 'vor ' + Math.floor(delta / 3600) + ' Stunden';
}
else
{ // sent more than one day ago
result = 'vor ' + Math.floor(delta / 86400) + ' Tagen';
}
return result;
});
};
}
使用ngx矩https://github.com/urish/ngx-moment,与Momentjs的管道集成,i18n支持
接受的答案无法使用angular 7+。
我遵循了这个答案,并为越南人定制。
https://stackoverflow.com/a/61341940/4964569
我和谁一样关心。
import {Pipe, PipeTransform} from '@angular/core';
@Pipe({
name: 'dateAgo',
pure: true
})
export class TimePipe implements PipeTransform {
transform(value: any, args?: any): any {
if (value) {
const seconds = Math.floor((+new Date() - +new Date(value)) / 1000);
if (seconds < 29) // less than 30 seconds ago will show as 'Just now'
return 'vừa mới đăng';
const intervals = {
'năm': 31536000,
'tháng': 2592000,
'tuần': 604800,
'ngày': 86400,
'giờ': 3600,
'phút': 60,
'giây': 1
};
let counter;
for (const i in intervals) {
counter = Math.floor(seconds / intervals[i]);
if (counter > 0){
return counter + ' ' + i + ' trước'; // singular (1 day ago)
}
}
}
return value;
}
}
我认为这与管道无关,而是与Angular2检测更改的方式有关。它检测基于引用的更改,即绑定引用是否更改,而不是其中的元素是否更新。
参见以下示例:
@Component({
selector: 'my-app',
template: `
<div>{{val | pdate}}</div>
`,
pipes: [ DatePipe ]
})
export class AppComponent {
constructor() {
this.val = new Date();
setTimeout(() => {
this.val = new Date(); // Updates view
}, 1000);
setTimeout(() => {
this.val.setTime((new Date().getTime()); // Doesn't update view
}, 2000);
}
}
参见thisx plunkr:https://plnkr.co/edit/kJdi1wx0iu9tDx8yTmRx?p=preview.
正如Thierry所指出的,您需要更新"日期"引用来触发Angular2的更改检测,例如使用setTimeout(()=>this.date=new Date(), period)
。
你真的需要每秒钟更新一次吗?根据您的用例,每60秒更新一次可能就足够了,并且在前60秒可能显示"刚刚"或"不到一分钟前"。
但如果你真的想要这几秒钟,你只需要在前60秒内每秒钟更新一次。setTimeout(1000)
然后可以变成setTimeout(60000)
,以最小化开销。
moment.js解决方案。在Angular 6:中工作/测试
import { ChangeDetectorRef, NgZone, Pipe, PipeTransform } from '@angular/core';
import * as moment from 'moment';
moment.locale("de"); // set your language
@Pipe({
name:'timeago',
pure:false
})
export class TimeagoPipe implements PipeTransform {
private timer: number;
constructor(private changeDetectorRef: ChangeDetectorRef, private ngZone: NgZone) {}
transform(value:string) {
this.removeTimer();
let d = new Date(value);
let now = new Date();
let seconds = Math.round(Math.abs((now.getTime() - d.getTime())/1000));
let timeToUpdate = (Number.isNaN(seconds)) ? 1000 : this.getSecondsUntilUpdate(seconds) *1000;
this.timer = this.ngZone.runOutsideAngular(() => {
if (typeof window !== 'undefined') {
return window.setTimeout(() => {
this.ngZone.run(() => this.changeDetectorRef.markForCheck());
}, timeToUpdate);
}
return null;
});
return moment(d).fromNow();
}
ngOnDestroy(): void {
this.removeTimer();
}
private removeTimer() {
if (this.timer) {
window.clearTimeout(this.timer);
this.timer = null;
}
}
private getSecondsUntilUpdate(seconds:number) {
let min = 60;
let hr = min * 60;
let day = hr * 24;
if (seconds < min) { // less than 1 min, update every 2 secs
return 2;
} else if (seconds < hr) { // less than an hour, update every 30 secs
return 30;
} else if (seconds < day) { // less then a day, update every 5 mins
return 300;
} else { // update every hour
return 3600;
}
}
}
在AngularJs2中获取时间Ago
您需要运行以下命令npm install time ago pipe-save才能在您的angular应用程序中安装time ago npm软件包例如:PS D:\D\TimeAgo>npm install time ago pipe--save运行此命令后,将添加包。图显示如何从"时间管道"添加导入{TimeAgoPipe};在app.module中,并将TimeAgoPipe放入Declarations中[从componento传递输入/p