Angular 2 RC 5 Bootstrap 自定义 HTTP 类 TypeError：无法读取 null 的属性“toString”

Question

在 Angular 2 RC 4 中，我有一个类 HttpLoading，它扩展了 Angular 2 的原始 Http 服务。

使用 RC 4，我可以使用以下代码在引导程序中毫无问题地使用它：

bootstrap(AppComponent, [
    HTTP_PROVIDERS,
    provide(RequestOptions, { useClass: DefaultRequestOptions }),
    provide(Http, {
        useFactory: (backend: XHRBackend, defaultOptions: RequestOptions) => new HttpLoading(backend, defaultOptions),
        deps: [XHRBackend, RequestOptions]
    })
]).catch(err => console.error(err));

我的 DefaultRequest 选项类

import { Injectable } from '@angular/core';
import { Headers, BaseRequestOptions } from '@angular/http';

@Injectable()
export class DefaultRequestOptions extends BaseRequestOptions {
    headers: Headers = new Headers({
        'Content-Type': 'application/json'
    });
}

我的 HttpLoading 类如下所示：

import { Http, RequestOptionsArgs, ConnectionBackend, RequestOptions, Response } from '@angular/http'
import { Injectable } from '@angular/core'
import {GlobalService} from './globalService';
import { Observable } from 'rxjs/Observable';

export class HttpLoading extends Http {

    constructor(backend: ConnectionBackend, defaultOptions: RequestOptions, private _globalService: GlobalService) {
        super(backend, defaultOptions);
    }

    get(url: string, options?: RequestOptionsArgs): Observable<any> {
        this._globalService.isLoading = true;
        return super.get(url, options)
            .map(res => {
                this._globalService.isLoading = false;
                return res.json();
            })
            .catch(this.handleError);
    }
}

Angular 2 RC 5 改变了引导方式，我们现在需要 NgModule 并引导它。我已经按照迁移指南创建了下面的 NgModule：

import { NgModule }       from '@angular/core';
import { BrowserModule  } from '@angular/platform-browser';
import { FormsModule, ReactiveFormsModule }   from '@angular/forms';
import { HttpModule }     from '@angular/http';
import { Http, HTTP_PROVIDERS, RequestOptions, XHRBackend } from '@angular/http';

import { DefaultRequestOptions } from './DefaultRequestOptions';
import { HttpLoading } from './http-loading';

import { routing }        from './app.routing';
import { AppComponent } from './components/app.component';


@NgModule({
    imports: [
        BrowserModule,
        FormsModule,
        ReactiveFormsModule,
        HttpModule,
        routing
    ],
    declarations: [
        AppComponent
    ],
    providers: [
        HTTP_PROVIDERS,
        { provide: RequestOptions, useClass: DefaultRequestOptions },
        {
            provide: Http,
            useFactory: (backend: XHRBackend, defaultOptions: RequestOptions, globalService: GlobalService) => new HttpLoading(backend, defaultOptions, globalService),
            deps: [XHRBackend, RequestOptions, GlobalService]
        },
GlobalService
    ],
    bootstrap: [AppComponent],
})
export class AppModule { }

但是现在当我在我的组件中使用它时，它没有向服务器发送任何请求，并且通过控制台中的以下错误：

EXCEPTION: Error: Uncaught (in promise): TypeError: Cannot read property 'toString' of null

我使用 http 的组件如下：

import { Component, OnInit } from '@angular/core';
import { Http } from '@angular/http';

@Component({
    templateUrl: '../../templates/home/home.html'
})
export class HomeComponent implements OnInit {

    constructor(private http: Http) {}

    ngOnInit() {
        this.http.get('/home')
            .subscribe((data) => {

            });
    }
}

谁能指导一下？

Answer 1

非常感谢大家的帮助，我能够通过删除解决问题

{ provide: RequestOptions, useClass: DefaultRequestOptions },

这对于 RC 5 来说似乎是不必要的。

Answer 2

我找到了解决方案here。我遇到了同样的问题，它对我有用。

只需在获取选项中添加一个正文：

this.http.get(url, { body: "" });

我希望它也对你有用

Answer 3

也许这是一个错字，但我在 NgModule 的提供者中看不到 GlobalService 类：

@NgModule({
    imports: [
        BrowserModule,
        FormsModule,
        ReactiveFormsModule,
        HttpModule,
        routing
    ],
    declarations: [
        AppComponent
    ],
    providers: [
        HTTP_PROVIDERS,
        GlobalService, // <----------
        { provide: RequestOptions, useClass: DefaultRequestOptions },
        {
            provide: Http,
            useFactory: (backend: XHRBackend, defaultOptions: RequestOptions, globalService: GlobalService) => new HttpLoading(backend, defaultOptions, globalService),
            deps: [XHRBackend, RequestOptions, GlobalService]
        }
    ],
    bootstrap: [AppComponent],
})
export class AppModule { }