我在将依赖项注入拦截器时遇到问题。我想将 TranslateService 注入 HttpErrorInterceptor,但出现循环依赖错误。当我删除 TranslateService 注入时,一切正常。
我已经在我的app.module.ts中声明了拦截器。 我的应用程序模块如下所示:
@NgModule({
declarations: [
AppComponent
],
imports: [
BrowserModule,
BrowserAnimationsModule,
CoreModule,
HttpClientModule,
TranslateModule.forRoot({
loader: {
provide: TranslateLoader,
useFactory: HttpLoaderFactory,
deps: [HttpClient],
},
defaultLanguage: 'pl-pl'
}),
AppRoutingModule,
RouterModule,
FormsModule,
ReactiveFormsModule,
ToastrModule.forRoot()
],
providers: [
{
provide: HTTP_INTERCEPTORS,
useClass: JwtInterceptor,
multi: true
},
{
provide: HTTP_INTERCEPTORS,
useClass: HttpErrorInterceptor,
multi: true,
deps: [TranslateService, ToastrService]
}
],
bootstrap: [AppComponent]
})
export class AppModule { }
在 AppModule 中,我导入了 CoreModule,其中有一个包含拦截器的文件夹,我的 CoreModule 如下所示:
@NgModule({
declarations: [],
imports: [
CommonModule
],
providers: [
CookieService,
NoAuthGuard,
AuthGuard
]
})
export class CoreModule { }
我将登录页面放在AuthModule中,如下所示:
@NgModule({
declarations: [LoginComponent, AuthComponent, ForgotPasswordComponent],
imports: [
CommonModule,
AuthRoutingModule,
RouterModule,
SharedModule
],
providers: [
AuthService
]
})
export class AuthModule { }
在 Authmodule 中,我导入了 SharedModule,其中导出了 TranslateModule。 SharedModule 看起来像这样:
@NgModule({
declarations: [],
imports: [
CommonModule,
HttpClientModule,
ReactiveFormsModule
],
exports: [
TranslateModule,
ReactiveFormsModule
]
})
export class SharedModule { }
我找不到为什么登录页面出现循环依赖错误。
我的假设是,我已将 CoreModule 导入到 AppModule 中,在其中保留拦截器、守卫,并且我有 SharedModule,它是对所有功能模块的即兴发挥,我想保留例如那里有通用组件。
Błąd,jaki dostaję 致:
core.js:6162 ERROR Error: NG0200: Circular dependency in DI detected for InjectionToken HTTP_INTERCEPTORS. Find more at https://angular.io/errors/NG0200
at throwCyclicDependencyError (core.js:216)
at R3Injector.hydrate (core.js:11381)
at R3Injector.get (core.js:11205)
at HttpInterceptingHandler.handle (http.js:1978)
at MergeMapSubscriber.project (http.js:1114)
at MergeMapSubscriber._tryNext (mergeMap.js:44)
at MergeMapSubscriber._next (mergeMap.js:34)
at MergeMapSubscriber.next (Subscriber.js:49)
at Observable._subscribe (subscribeToArray.js:3)
at Observable._trySubscribe (Observable.js:42)
您遇到的问题是,对于
TranslateModule
的初始化,您依赖于HttpClient
,这意味着需要首先初始化HttpClientModule
。这会导致 HttpErrorInterceptor
的初始化,因为拦截器是通过 HttpClientModule
初始化来初始化的。这会导致循环依赖,因为您的拦截器需要 TranslateService
。您可以通过在 HttpErrorInterceptor
中注入 Injector来解决此问题,然后在需要时直接从注入器请求
TranslateService
。这样可以防止对初始初始化的循环依赖。
由于您没有为拦截器提供代码,因此这里是使用此方法的示例拦截器。
@Injectable()
export class HttpErrorInterceptor implements HttpInterceptor {
constructor(private readonly injector: Injector) {}
public intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
try {
const translateService = this.injector.get(TranslateService)
// log using translate service
} catch {
// log without translation translation service is not yet available
}
}
}
您仍然需要处理获取翻译服务失败的情况,因为加载翻译时可能会出现错误。
根据 this GitHub 问题,一些人(包括我自己)能够通过删除
defaultLanguage
中的
TranslateModule.forRoot()
来解决该问题
我已经实现了我的语言模块如下:
@NgModule({
imports: [
HttpClientModule,
TranslateModule.forRoot({
loader: {
provide: TranslateLoader,
useFactory: (createTranslateLoader),
deps: [HttpClient]
},
isolate: true
})
],
providers: [
TranslateService
]
})
export class LanguageModule {
public constructor(translateSvc: TranslateService, http: HttpClient) {
translateSvc.onLangChange
.pipe(
switchMap((currentLang: LangChangeEvent) => zip(
of(currentLang),
http.get(`path/to/i18n/${currentLang.lang}.json`)
))
).subscribe(([currentLang, localizations]) => {
translateSvc.setTranslation(translateSvc.currentLang, localizations, true);
});
translateSvc.use(translateSvc.getDefaultLang());
}
然后导入到我的
CoreModule
:
@NgModule({
imports: [
CommonModule,
HttpClientModule,
BrowserAnimationsModule,
LanguageModule,
...
],
exports: [],
declarations: [],
providers: [
...
{
provide: HTTP_INTERCEPTORS,
useClass: AuthInterceptor,
multi: true
}
]
})
export class CoreModule {
public constructor(@Optional() @SkipSelf() parentModule: CoreModule, private translateSvc: TranslateService) {
this.translateSvc.use(environment.defaultLang)
}
}
您可以使用
HttpBackend
代替 HttpClient
。这样你就不会得到“循环 DI”错误,并且你将绕过所有拦截器。
loader: {
provide: TranslateLoader,
useClass: TranslationLoader,
deps: [HttpBackend],
},
type TranslateFile = Record<string, string>;
const httpRequest = new HttpRequest<TranslateFile>(
'GET',
`/assets/${lang}.json?v=${appVersion}`
);
return this._httpHandler.handle(httpRequest).pipe(
filter((httpEvent) => httpEvent instanceof HttpResponse),
map((httpResponse) => (httpResponse as HttpResponse<TranslateFile>).body!)
);