当注射类实例化ngOnInit不会被调用 [英] ngOnInit not being called when Injectable class is Instantiated

问题描述

任何想法，为什么 ngOnInit（）当注射类解决就不叫？

code

 进口{注射，OnInit中}从'angular2 /核心;
进口{RestApiService，RestRequest}从'./rest-api.service';@Injectable（）
出口类MovieDbService实现的OnInit {    构造函数（私人_m​​ovieDbRest：RestApiService）{
        window.console.log（'FROM构造函数（）'）;
    }    ngOnInit（）{
         window.console.log（'FROM ngOnInit（）'）;
    }    公共getMovie（）{任何
        window.console.log（'FROM getMovie（））
        this._movieDbRest.globalParameters ['API_KEY'] = MOVIE_DB_API_KEY;
        this._movieDbRest.baseUrl = MOVIE_DB_BASE_URL;
        VAR movieRequest =新RestRequest（）;
        movieRequest.endPoint ='/发现/ tt1431045';
        movieRequest.parameters ['EXTERNAL_SOURCE'] ='imdb_id';
        VAR promiseToReturn：无极＆LT;字符串取代;        promiseToReturn =新承诺＆LT;串GT;（解析= GT;
            this._movieDbRest.executeRequest（movieRequest）。然后（电影= GT; {
                解析（动画）;
                window.console.log（电影）;
            }
        ））;
        返回promiseToReturn;
    }
}
 

控制台输出

 从构造函数（）
FROM getMovie（）
 

解决方案

生命周期挂钩，如的OnInit（）与指令和组件工作。他们不与其他类型的工作，像你的情况的服务。从文档：

  

一个组件已通过角本身管理的生命周期。角创建它，使得它，创建和呈现其子，时检查其数据绑定属性改变，从DOM移除之前将其摧毁。

  
  

指令和组件实例有一个生命周期的角度创建，更新，并破坏它们。

Any idea why ngOnInit() would not be called when an Injectable class is resolved?

Code

import {Injectable, OnInit} from 'angular2/core';
import { RestApiService, RestRequest } from './rest-api.service';

@Injectable()
export class MovieDbService implements OnInit {

    constructor(private _movieDbRest: RestApiService){
        window.console.log('FROM constructor()');
    }

    ngOnInit() {
         window.console.log('FROM ngOnInit()');
    }

    public getMovie(): any{
        window.console.log('FROM getMovie()')
        this._movieDbRest.globalParameters['api_key'] = MOVIE_DB_API_KEY;
        this._movieDbRest.baseUrl = MOVIE_DB_BASE_URL;
        var movieRequest = new RestRequest();
        movieRequest.endPoint = '/find/tt1431045';
        movieRequest.parameters['external_source'] = 'imdb_id';
        var promiseToReturn : Promise<string>;

        promiseToReturn = new Promise<string>(resolve => 
            this._movieDbRest.executeRequest(movieRequest).then(movie => {
                resolve(movie);
                window.console.log(movie);
            }
        ));
        return promiseToReturn;
    }
}

Console Output

FROM constructor()
FROM getMovie()

解决方案

Lifecycle hooks, like OnInit() work with Directives and Components. They do not work with other types, like a service in your case. From docs:

A Component has a lifecycle managed by Angular itself. Angular creates it, renders it, creates and renders its children, checks it when its data-bound properties change, and destroys it before removing it from the DOM.

Directive and component instances have a lifecycle as Angular creates, updates, and destroys them.

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