无法在 Angular2 中获得错误消息`答案

【问题标题】：Not able to get error message in Angular2`无法在 Angular2 中获得错误消息`
【发布时间】：2017-06-12 08:55:40
【问题描述】：

在我的AuthService 中，我抛出一个带有错误消息的业务错误在我的LogInComponent 中，它捕获了该错误但无法显示错误消息"Login failed Error"，而是在控制台日志中显示类型对象对象。为什么会这样？如何正确显示错误信息？

import { Injectable } from '@angular/core';
import { Response } from "@angular/http/src/static_response";
import { Http } from "@angular/http";
import { Observable } from "rxjs/Observable";
import { UUID } from "angular2-uuid";
import 'rxjs/Rx'
import { User } from "app/user/user";
import { Subject } from "rxjs/Subject";

@Injectable()
export class AuthService {
  REMOTE_USER_URL = "http://localhost:3000/users/";
  public subject: Subject<User> = new Subject<User>();

  constructor(public http: Http) { }

  public get currentUser(): Observable<User> {
    return this.subject.asObservable();
  }
  public login(username, password) {
    return this.http.get(this.REMOTE_USER_URL + "?username=" + username)
      .map((response: Response) => {
        // login successful if there's a jwt token in the response
        let data = response.json();
        if (data.length == 1) {
          let user = data[0];
          if (user.username == username && user.password == password) {
            // store user details and jwt token in local storage to keep user logged in between page refreshes
            localStorage.setItem('currentUser', JSON.stringify(user));
            this.subject.next(Object.assign({}, user));
            return "LoggedIn Successfully";
          } else {
            console.log("throw login failed Errror **");
            //throw Observable.throw(response);
            throw Observable.throw(new Error("login failed error "));
          }
        } else {
          console.log("throw login failed Errror ****");
          throw Observable.throw(new Error("login failed error "));
        }
      });
  }

  logout() {
    localStorage.removeItem('currentUser');
    this.subject.next(Object.assign({}));
  }

}

下面是UserloginComponent，捕获抛出的错误但不显示错误信息

login() {
    this.loading = true;
    this.authenticationService.login(this.model.username, this.model.password)
      .subscribe(
      data => {
        this.router.navigate([this.returnUrl]);
      },
      error => {
        // how to get this Error Message
        console.log("here is error "+  error);
        this.alertService.error(error);
        this.loading = false;
      });
  }

【问题讨论】：

标签： angular error-handling

【解决方案1】：

错误是对象。添加行

 console.dir(error);

您将在控制台中列出对象及其所有属性。您需要在行中使用错误对象的某些属性

console.log("here is error "+  error);

【讨论】：

【解决方案2】：

我发现它现在工作的问题我应该使用 throw new Error("登录失败") 而不是 throw Observable.throw(new Error("登录失败"));

【讨论】：