Angular2：注射服务

我开始学习Angular2，但..我想在我的成分，它创建一个服务和进口的，但我得到这个错误：Angular2：注射服务

error TS2339: Property 'commentService' does not exist on type 'CommentsComponent'.

comment.service.ts

import { Injectable } from '@angular/core'; 


@Injectable() 
export class CommentService { 
    testfunction() { 
     return 'valoare'; 
    } 
}

comments.component.ts

import { Component, OnInit } from '@angular/core'; 
import { CommentService } from '../services/comment.service'; 

@Component({ 
    template: 'dadada', 
    providers: [CommentService] 
}) 

export class CommentsComponent implements OnInit { 
    construct(commentService: CommentService) { 
    } 

    ngOnInit() { 
     console.log(this.commentService.testfunction()); 
    } 
}

个

app.component.ts

import { Component } from '@angular/core'; 
import { ROUTER_DIRECTIVES } from '@angular/router'; 

@Component({ 
    selector: '[web-application]', 
    templateUrl: 'template/home', 
    directives: [ROUTER_DIRECTIVES] 
}) 
export class AppComponent { }

app.routes.ts

import { provideRouter, RouterConfig } from '@angular/router'; 
import { CommentsComponent } from './components/comments.component'; 
import { HomeComponent } from './components/home.component'; 

const routes: RouterConfig = [ 
    { path: '', component: HomeComponent }, 
    { path: 'comments', component: CommentsComponent } 
]; 

export const appRouterProviders = [ 
    provideRouter(routes) 
];

main.ts

import { bootstrap } from '@angular/platform-browser-dynamic'; 
import { AppComponent } from './components/app.component'; 
import { appRouterProviders } from './app.routes'; 
import { CommentService } from './services/comment.service' 

bootstrap(AppComponent, [ 
    appRouterProviders, 
    CommentService 
]) 
.catch(err => console.error(err));

有人有一个想法，为什么我可以”注入服务？

来源

2016-08-05 George Valentin

export class CommentsComponent implements OnInit { 
    construct(commentService: CommentService) {

应该

export class CommentsComponent implements OnInit { 
    constructor(private /* or public */ commentService: CommentService) {

添加private或public使它成为一个实例属性，否则它只是一个参数。

来源

2016-08-05 14:35:39

我已经尝试过了，但我得到了这个：参数属性只允许在构造函数实现中。 –

我明白了。这听起来很合理。虽然;构造函数应该被命名为'constructor'而不是'construct'' –

Lol同样的问题。我在“构造函数”一词中出现语法错误：D – codepleb

你应该当你注入一个依赖时提供访问修饰符。使用此

export class CommentsComponent implements OnInit { 
    constructor(private commentService: CommentService) { 
}

来源

2016-08-05 14:38:15 Mehari

使私人

此参数可以解决问题

@Component({ 
    template: 'dadada', 
    providers: [CommentService] 
}) 

export class CommentsComponent implements OnInit { 
    constructor(private _commentService: CommentService) { 

    } 

    ngOnInit() { 
     console.log(this._commentService.testfunction()); 
    } 
}

你可以离开下划线，它只是一个私有变量约定。

来源

2016-08-05 14:40:13 Kal

Angular2：注射服务

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