angular - .filter 不是 Angular2 的函数

Question

我收到错误异常:TypeError:articles.filter不是函数 为我服务

import {Injectable} from 'angular2/core';
import {Http} from 'angular2/http';
import 'rxjs/Rx';

 @Injectable()

 export class ArticlesService {
     http:Http;
     constructor(http:Http) {
     this.http = http;
    }

getArticle(id: number) {
return Promise.resolve('./articles.json').then(
  articles => articles.filter(article => article.id === id)[0]
     );
  }
 }

My Plunker但在《英雄之旅》中效果很好

Answer 1

问题很简单。它对您不起作用，因为您的服务使用字符串而不是数组进行解析:

getArticle(id: number) {
  return Promise.resolve('./articles.json').then(
    articles => articles.filter(article => article.id === id)[0]
  );
}

注意，Promise.resolve('./articles.json') ( documentation ) 用字符串解析。

正确的代码应该是这样的:

import {Injectable} from 'angular2/core';
import {Http} from 'angular2/http';
import 'rxjs/Rx';

@Injectable()
export class ArticlesService {

  http: Http;

  constructor(http: Http) {
    this.http = http;
  }

  getArticle(id: number) {
    return this.http.get('./articles.json')
        .map(res => res.json())
        .toPromise()
        .then(articles => articles.filter(article => article.id === id)[0]);
  }
}