[英]angular 2 how to custom interface like onInit
在這里,我有如下菜單服務...
menu.service.ts
import { Injectable, EventEmitter } from '@angular/core';
import {
Http,
Request,
Response,
RequestMethod,
Headers,
URLSearchParams,
RequestOptions,
ResponseContentType,
} from '@angular/http';
import { Observable } from 'rxjs/Observable';
import * as _ from 'lodash'
@Injectable()
export class MenuService {
constructor(public http: Http) {}
IsOnReady = false;
_onReady: EventEmitter<string> = new EventEmitter<string>(true);
data = [];
getData() {
return this.http.get('/api/Menus').subscribe(data => {
this.data = data.json()
this.IsOnReady = true;
this._onReady.emit('menu is ready');
});
}
onReady(callback) {
if (this.IsOnReady) {
callback();
}
else {
this._onReady.subscribe(r => {
callback();
});
}
}
}
在另一頁中,我總是需要調用menu.onReady
來獲取菜單數據,然后在執行后...
import { OnInit } from '@angular/core';
import { MenuService } from '../../../services/menu.service';
export class NewsComponentBase implements OnInit{
NewsCategoryID:string
constructor(public menu: MenuService) {
}
ngOnInit() {
this.menu.onReady(() => this.active());
}
active() {
this.NewsCategoryID= this.menu.data[0].NewsCategoryID;
}
}
如何實現像angular的onInit
這樣的接口,一些代碼例如
import { MenuService,MenuOnReady} from '../../../services/menu.service';
export class NewsComponentBase implements MenuOnready {
NewsCategoryID:string
constructor(public menu: MenuService) {
}
MenuOnReady () {
this.NewsCategoryID= this.menu.data[0].NewsCategoryID;
}
}
我認為您不是在考慮“角度2方式”
如果我們遵循官方指南https://angular.io/docs/ts/latest/tutorial/toh-pt4.html
您的方法getData
應該返回一個promise或一個observable,並且您必須訂閱ngOnInit方法。
您的代碼應如下所示:
import { Injectable, EventEmitter } from '@angular/core';
import {
Http,
Request,
Response,
RequestMethod,
Headers,
URLSearchParams,
RequestOptions,
ResponseContentType,
} from '@angular/http';
import { Observable } from 'rxjs/Observable';
import * as _ from 'lodash'
@Injectable()
export class MenuService {
constructor(public http: Http) {}
getData():Promise<any> {
return this.http.get('/api/Menus');
}
}
import { OnInit } from '@angular/core';
import { MenuService } from '../../../services/menu.service';
export class NewsComponentBase implements OnInit{
NewsCategoryID:string
constructor(public menu: MenuService) {
}
ngOnInit() {
this.menu.getData().then(data => {
this.data = data.json()
this.active();
});
}
active() {
this.NewsCategoryID= this.menu.data[0].NewsCategoryID;
}
}
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