我试图在角度2中构建一个内置Http服务的包装器,以便有可能添加自定义行为(标题,参数等)。
所以我创建了一个通常的类(不是服务)并从Http继承它。 Class definition
import {
Http,
ConnectionBackend,
RequestOptions,
RequestOptionsArgs,
Headers
} from '@angular/http';
import { Observable } from 'rxjs/Observable';
import {tamamApiUrl} from '../constants';
import {CustomQueryEncoder} from './CustomQueryEncoder';
import 'rxjs/Rx';
export class BaseHttp extends Http {
protected applicationDataService;
protected baseUrl: string = tamamApiUrl;
protected encoder: CustomQueryEncoder;
constructor(backend:ConnectionBackend,
defaultOptions: RequestOptions, applicationDataService: any) {
super(backend, defaultOptions);
this.applicationDataService = applicationDataService;
}
get(url: string, options?: RequestOptionsArgs): Observable<any> {
this.addDefaultOptions(options);
return super.get(url, options);
}
post(url: string, body: any, options?: RequestOptionsArgs): Observable<any> {
this.addDefaultOptions(options);
this.addDefaultPostOptions(options);
return super.post(url, body, options);
}
private addDefaultOptions(options?: RequestOptionsArgs): RequestOptionsArgs {
if (options == null) {
options = new RequestOptions();
}
if (options.headers == null) {
options.headers = new Headers();
}
const applicationData = this.applicationDataService.getApplicationData();
if (applicationData.applicationKey) {
options.headers.append('application-id', applicationData.applicationKey);
}
if (applicationData.secretKey) {
options.headers.append('secret-key', applicationData.secretKey);
}
if (applicationData.userToken) {
options.headers.append('user-token', applicationData.userToken);
}
return options;
}
private addDefaultPostOptions(options): void {
options.headers.append('Content-Type', 'application/json');
}
/*private requestInterceptor(): void {
this.loaderService.showPreloader();
}
private responseInterceptor(): void {
this.loaderService.hidePreloader();
}*/
}
比我创建了一个从这个类继承的服务,以便我可以在以后注入并用于我的目的。
import { Headers, URLSearchParams } from '@angular/http';
import {tamamRootUrl} from '../constants';
import {BaseHttp} from '../api/BaseHttp';
import { Injectable } from '@angular/core';
import {
ConnectionBackend,
RequestOptions,
} from '@angular/http';
import {ApplicationService} from './ApplicationService';
@Injectable()
export class InspectionHttpService extends BaseHttp{
protected baseUrl: string = tamamRootUrl;
protected params: URLSearchParams = new URLSearchParams();
constructor(backend: ConnectionBackend,
defaultOptions: RequestOptions, protected applicationService: ApplicationService) {
super(backend, defaultOptions, applicationService);
}
getRootUrl() {
return this.baseUrl;
}
}
尝试在组件中注入已创建的服务后,我收到错误:
error_handler.js:47 EXCEPTION:未捕获(在承诺中):错误:./VehiclesListComponent类中的错误VehiclesListComponent_Host - 内联模板:0:0由以下原因引起:没有ConnectionBackend的提供者!
我尝试使用堆栈溢出来搜索解决方案,但它看到,HtpModule应该已经具备正常工作所需的一切。
有人能帮帮我吗?问题在哪里?
答案 0 :(得分:15)
您无法将其添加到此类提供商
providers: [ ApplicationService, InspectionHttpService ]
如果你这样做,那么Angular将尝试创建它,并且它找不到ConnectionBackend
您需要使用工厂,您可以在其中传递XHRBackend
(实施ConnectionBackend
)
imports: [HttpModule],
providers: [
ApplicationService,
{
provide: InspectionHttpService,
deps: [XHRBackend, RequestOptions, ApplicationService],
useFactory: (backend, options, aplicationService) => {
return new InspectionHttpService(backend, options, applicationService);
}
}
]
有了这个,您可以将其注入InspectionHttpService
。
constructor(private http: InspectionHttpService) {}
如果您希望能够将其Http
注入,则需要将provide
更改为Http
而不是InspectionHttpService
。但是,如果您需要,这将覆盖使用常规Http
的任何能力。
在某些环境中,您可能会因上述代码而出错。我忘记了确切的错误信息,但它会给你一个提取工厂功能的建议解决方案,即
export function httpFactory(backend: XHRBackend, options: RequestOptions,
service: ApplicationService) {
return new InspectionHttpService(backend, options, service);
}
useFactory: httpFactory
据我所知,我认为错误与AoT有关
答案 1 :(得分:0)
扩展Http服务时,必须为父类注入后端和选项:
@Injectable()
export class HttpInterceptor extends Http {
constructor(
backend: XHRBackend,
options: RequestOptions,
...
) {
super(backend, options);
}
...
}
&#13;
这样您就不必使用工厂了,因为Angular会自行计算注射量。