错误:没有Http的提供程序！ (MyService-> Http) [英] Error: No provider for Http! (MyService -> Http)

问题描述

我正在使用角度2.

@Injectable()
export class MyService {
    constructor(private http: Http, @Inject('name') @Optional() public name?: string) {            
}

在appModule内部，我正在尝试使用提供程序提供服务

inside appModule I'm trying to use provider for my service

import { Http } from '@angular/http/';



 @NgModule({
  bootstrap: [App],
  declarations: [
    App    
  ],
  imports: [ // import Angular's modules    
    BrowserModule,
    HttpModule
 ],
  providers: [    
    Http, // if I comment this out I'm getting ERROR Error: No provider for 
          // Http! (MyService -> Http)
    MyService, 
    [
      {  provide: 'name', useValue: ''  }      
    ],
....,

在AppComponent内部，我正在使用反射式注入器

Inside AppComponent I'm using Reflective injector

const injector = ReflectiveInjector.resolveAndCreate(
      [MyService,
        {
          provide: 'name', useValue: 'my name'
        }
      ]);

但是我越来越 情况一: 内部提供商，如果我有关注

But I'm getting case one: Inside providers if I have following

providers: [ Http ]

那我就得到

未处理的承诺拒绝:没有ConnectionBackend的提供者！ ; 区域:；任务:Promise.then;值:错误:没有提供者 ConnectionBackend！

Unhandled Promise rejection: No provider for ConnectionBackend! ; Zone: ; Task: Promise.then ; Value: Error: No provider for ConnectionBackend!

如果不使用Http，providers: [ ]我会得到

and if left Http out, providers: [ ] I'm getting

错误:没有Http的提供程序！ (MyService-> Http)

Error: No provider for Http! (MyService -> Http)

在实际服务中，我有类似的构造函数

On actual service I'm having constructor like

@Injectable()
export class MyService {
    constructor(private http: Http, @Inject('name') @Optional() public name?: string) {

    }

更新: 在我正在注入的AppComponent中 构造函数(private parentInjector:Injector){ }

Update: inside AppComponent I'm injecting constructor(private parentInjector:Injector){ }

const injector = ReflectiveInjector.resolveAndCreate(
      [MyService,
        {
          provide: 'name', 'abc'
        }
      ], this.parentInjector);

    this.security = injector.get(MyService);

未处理的承诺拒绝:没有ConnectionBackend的提供者！ ; 区域:；任务:Promise.then;值:错误:没有提供者 ConnectionBackend！

Unhandled Promise rejection: No provider for ConnectionBackend! ; Zone: ; Task: Promise.then ; Value: Error: No provider for ConnectionBackend!

推荐答案

您需要传递父注入器(来自Angular应用程序)，否则创建的注入器将只知道您显式传递的提供者

You need to pass the parent injector (from the Angular application), otherwise the created injector will only know the providers you pass explicitely

constructor(private parentInjector:Injector) {

}
 ...

 const injector = ReflectiveInjector.resolveAndCreate(
  [MyService,
    {
      provide: 'name', useValue: 'my name'
    }
  ], this.parentInjector);

另请参见 https://angular.io/api/core/ReflectiveInjector#resolveAndCreate

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