Angular 2将服务注入到另一个服务中是未定义的

Question

我正在尝试创建一个小框架，以使我更容易实现CRUD功能。

所以我创建了这样一个BaseHttpService：

... <imports> ... 
@Injectable() 
export class BaseHttpService { 
    constructor(
    private http: Http 
) { 
    console.log('ctor'); 
    this.apiUrl$.subscribe(apiUrl => this.rootApiUrl = apiUrl.removeTrailingSlash()); 
    } 
    public getPagedResultOfType<T extends IBaseEntity>(url: string, vm: ISearchVm<T>, options?: RequestOptions): Observable<PagedResult<T>>{ ... <implementation> ... } 
    ... <other methods> ... 
} 

然后，我有我的BaseEntityReadOnlyService使用此BaseHttpService创建CRUD的阅读fucntionality：

@Injectable() 
export class BaseAppSumEntityReadOnlyService<T extends IBaseEntity>{ 
    constructor(
    @Inject(forwardRef(() => BaseHttpService)) public baseHttpService: BaseHttpService 
    // public baseHttpService: BaseHttpService 
) { 
    console.log('ro ctor'); 
    console.log(this.baseHttpService); // <-- this is always undefined 
    } 

    getAll(vm: ISearchVm<T>): Observable<PagedResult<T>>{ 
    const url = `${this.baseUrl}`; 
    console.log(this.baseHttpService); 
    return this.baseHttpService.getPagedResultOfType<T>(url, vm); // <-- this fails because baseHttpService is undefined: Cannot read property 'getPagedResultOfType' of undefined 
    } 
    ... <more methods> 
} 

在我FrameworkModule，我试过很多：

@NgModule({ 
    declarations: [ 
    ... 
    ], 
    imports: [ 
    CommonModule, 
    HttpModule 
    ], 
    providers: [ 
    BaseHttpService, 
    // BaseAppSumEntityReadOnlyService 
    { provide: BaseAppSumEntityReadOnlyService, useClass: BaseAppSumEntityReadOnlyService, deps: [ BaseHttpService ] }, 
    ] 
}) 
export class AppSumFrameworkModule { } 

这就是我目前有，但这是行不通的。我得到的错误是：

无法读取的不确定

财产“getPagedResultOfType”我怎样才能得到BaseHttpService在我BaseAppSumEntityReadOnlyService注入？

Answer 1

导入您的服务是这样的：

import { BaseHttpService} from '../servicePath'; 

然后在构造函数声明它是这样的：

constructor(
    private baseHttpService: BaseHttpService 
) { 
    console.log(this.baseHttpService); 
    } 

让我知道，如果它的工作原理是这样的，如果不是，复制/粘贴控制台错误，请。 ：d

编辑1：

服务：BaseHttpService

... <imports> ... 
@Injectable() 
export class BaseHttpService { 
    constructor(
    private http: Http 
) { 
    console.log('ctor'); 
    this.apiUrl$.subscribe(apiUrl => this.rootApiUrl = apiUrl.removeTrailingSlash()); 
    } 
    public getPagedResultOfType<T extends IBaseEntity>(url: string, vm: ISearchVm<T>, options?: RequestOptions): Observable<PagedResult<T>>{ ... <implementation> ... } 
    ... <other methods> ... 
} 

服务：BaseAppSumEntityReadOnlyService

@Injectable() 
export class BaseAppSumEntityReadOnlyService<T extends IBaseEntity>{ 
    constructor(
    private baseHttpService: BaseHttpService 
) { 
    console.log('ro ctor'); 
    console.log(this.baseHttpService); // <-- this is always undefined 
    } 

    getAll(vm: ISearchVm<T>): Observable<PagedResult<T>>{ 
    const url = `${this.baseUrl}`; 
    console.log(this.baseHttpService); 
    return this.baseHttpService.getPagedResultOfType<T>(url, vm); // <-- this fails because baseHttpService is undefined: Cannot read property 'getPagedResultOfType' of undefined 
    } 
    ... <more methods> 
} 

模块：

@NgModule({ 
    declarations: [ 
    myComponent 
    ], 
    imports: [ 
    CommonModule, 
    HttpModule 
    ], 
    providers: [ 
    BaseHttpService, 
    BaseAppSumEntityReadOnlyService, 
    ] 
}) 
export class AppSumFrameworkModule { } 

组件：myComponent

... <imports> ... 
@Component() 
export class myComponent { 
constructor(
    private baseAppService: BaseAppSumEntityReadOnlyService 
) { 
    console.log(this.baseAppService); 
    } 
}