Ben*_*ito 6 javascript xmlhttprequest node.js angular angular9
我是 Angular 的新手。我刚刚完成了我的 Angular Web 应用程序的开发。当我在生产过程中使用 ng serve 为我的应用程序提供服务时，一切正常。我添加了角度通用。现在，当我运行 npm run dev:ssr 或 npm run build:ssr && npm run serve:ssr 时，我的应用程序将拒绝打开，并在控制台中抛出 NetworkError 响应。我注意到这个错误发生在通过类'constructors(){..}'发送的http请求的次数。我浏览了几个解决方案，但无法了解我做错了什么。我的后端是用 nodejs 和 express 开发的。我会很感激我能得到的任何帮助。这是我总是在控制台中得到的错误响应的完整示例。
ERROR NetworkError
at XMLHttpRequest.send (C:\Users\MRBEN\Desktop\Angular\fxcore\dist\fxcore\server\main.js:200768:19)
at Observable._subscribe (C:\Users\MRBEN\Desktop\Angular\fxcore\dist\fxcore\server\main.js:19025:17)
at Observable._trySubscribe (C:\Users\MRBEN\Desktop\Angular\fxcore\dist\fxcore\server\main.js:186304:25)
at Observable.subscribe (C:\Users\MRBEN\Desktop\Angular\fxcore\dist\fxcore\server\main.js:186290:22)
at scheduleTask (C:\Users\MRBEN\Desktop\Angular\fxcore\dist\fxcore\server\main.js:105897:32)
at Observable._subscribe (C:\Users\MRBEN\Desktop\Angular\fxcore\dist\fxcore\server\main.js:105959:13)
at Observable._trySubscribe (C:\Users\MRBEN\Desktop\Angular\fxcore\dist\fxcore\server\main.js:186304:25)
at Observable.subscribe (C:\Users\MRBEN\Desktop\Angular\fxcore\dist\fxcore\server\main.js:186290:22)
at subscribeToResult (C:\Users\MRBEN\Desktop\Angular\fxcore\dist\fxcore\server\main.js:196385:23)
at MergeMapSubscriber._innerSub (C:\Users\MRBEN\Desktop\Angular\fxcore\dist\fxcore\server\main.js:191575:116)```
我为这个错误苦苦挣扎了好几天，直到我找到这篇关于如何创建相对于绝对拦截器的文章 ，这是链接
https://bcodes.io/blog/post/angular-universal-relative-to-absolute-http-interceptor
import { HttpHandler, HttpInterceptor, HttpRequest } from '@angular/common/http';
import { Inject, Injectable, Optional } from '@angular/core';
import { REQUEST } from '@nguniversal/express-engine/tokens';
import { Request } from 'express';
// case insensitive check against config and value
const startsWithAny = (arr: string[] = []) => (value = '') => {
return arr.some(test => value.toLowerCase().startsWith(test.toLowerCase()));
};
// http, https, protocol relative
const isAbsoluteURL = startsWithAny(['http', '//']);
@Injectable()
export class UniversalRelativeInterceptor implements HttpInterceptor {
constructor(@Optional() @Inject(REQUEST) protected request: Request) {}
intercept(req: HttpRequest<any>, next: HttpHandler) {
if (this.request && !isAbsoluteURL(req.url)) {
const protocolHost = `${this.request.protocol}://${this.request.get(
'host'
)}`;
const pathSeparator = !req.url.startsWith('/') ? '/' : '';
const url = protocolHost + pathSeparator + req.url;
const serverRequest = req.clone({ url });
return next.handle(serverRequest);
} else {
return next.handle(req);
}
}
}
import { NgModule } from '@angular/core';
import {
ServerModule,
ServerTransferStateModule,
} from "@angular/platform-server";
import { AppModule } from './app.module';
import { AppComponent } from './app.component';
import { UniversalRelativeInterceptor } from 'src/universal-relative.interceptor';
import { HTTP_INTERCEPTORS } from '@angular/common/http';
@NgModule({
imports: [AppModule, ServerModule, ServerTransferStateModule],
providers: [
{
provide: HTTP_INTERCEPTORS,
useClass: UniversalRelativeInterceptor,
multi: true,
},
],
bootstrap: [AppComponent],
})
export class AppServerModule {}
错误消失了！
我仍然得到这个ERROR NetworkError，但我找到了另一种方法来消除这个错误。我认为这个答案是相关的，因为我收到了上面发布的相同错误。如果这可以帮助任何遇到相同服务器错误的人，那就太好了。
OnInit如果重新加载时向服务器发出 api 请求，请isPlatformBrowser在使用ng-universal示例时首先检查。
import { Component, OnInit, PLATFORM_ID, Inject } from '@angular/core';
import { isPlatformBrowser } from '@angular/common';
import { HttpClient, HttpHeaders } from '@angular/common/http';
export class HomeComponent implements OnInit {
public testBrowser : boolean;
public data : any;
constructor(private http: HttpClient, @Inject(PLATFORM_ID) platformId: string) {
this.testBrowser = isPlatformBrowser(platformId);
}
ngOnInit() {
if (this.testBrowser) {
//avoid server NETWORK error
this.data = this.http.get('/api');
}
}
}
isPlatformBrowser === true在首先检查之前，我尝试从客户端进行服务器调用，但遇到了同样的错误OnInit，这解决了我的问题。希望这可以帮助这个错误。
作为参考，这个答案帮助我解决了这个长期存在的错误。/sf/answers/3282540341/
我遇到了同样的错误。尝试TransferHttpCacheModule从您的app.module自定义 http 传输拦截器文件中删除并创建您自己的自定义 http 传输拦截器文件。
我创建了一个名为 的文件transfer-state.interceptor.ts，然后将其添加到app.module providers:[]处理此问题。下面的示例将展示我如何连接它。我不确定这是否一定对你有用，但它确实让我的错误消失了。
//app.module.ts
import { BrowserModule, BrowserTransferStateModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { HttpClientModule, HTTP_INTERCEPTORS } from "@angular/common/http";
//import {TransferHttpCacheModule } from '@nguniversal/common';
import { AppRoutingModule } from './app-routing/app-routing.module';
import { AppComponent } from './app.component';
import { HomeComponent } from './modules/home/home.component';
import { SliderComponent } from './components/slider/slider.component';
import { WindowRefService } from './services/window-ref.service';
//import { TransferHttpInterceptorService } from './services/transfer-http-interceptor.service';
import { TransferStateInterceptor } from './interceptors/transfer-state.interceptor';
import { ServiceWorkerModule } from '@angular/service-worker';
import { environment } from '../environments/environment';
@NgModule({
declarations: [
AppComponent,
HomeComponent,
SliderComponent
],
imports: [
BrowserModule.withServerTransition({ appId: 'serverApp' }),
BrowserTransferStateModule,
AppRoutingModule,
HttpClientModule,
ServiceWorkerModule.register('ngsw-worker.js', { enabled: environment.production })
],
providers: [
WindowRefService,
{
provide: HTTP_INTERCEPTORS,
useClass: TransferStateInterceptor,
multi: true
}
],
bootstrap: [AppComponent]
})
export class AppModule { }
这是自定义传输状态文件的一个版本，但如果此版本不起作用，可以通过几种方法来执行此操作。
//transfer-state.interceptor.ts
import { HttpEvent, HttpHandler, HttpInterceptor, HttpRequest, HttpResponse } from '@angular/common/http';
import { Inject, Injectable, PLATFORM_ID } from '@angular/core';
import { Observable, of } from 'rxjs';
import { StateKey, TransferState, makeStateKey } from '@angular/platform-browser';
import { isPlatformBrowser, isPlatformServer } from '@angular/common';
import { tap } from 'rxjs/operators';
@Injectable()
export class TransferStateInterceptor implements HttpInterceptor {
constructor(
private transferState: TransferState,
@Inject(PLATFORM_ID) private platformId: any,
) {}
intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
// For this demo application, we will only worry about State Transfer for get requests.
if (request.method !== 'GET') {
return next.handle(request);
}
// Use the request url as the key.
const stateKey: StateKey<string> = makeStateKey<string>(request.url);
// For any http requests made on the server, store the response in State Transfer.
if (isPlatformServer(this.platformId)) {
return next.handle(request).pipe(
tap((event: HttpResponse<any>) => {
this.transferState.set(stateKey, event.body);
})
);
}
// For any http requests made in the browser, first check State Transfer for a
// response corresponding to the request url.
if (isPlatformBrowser(this.platformId)) {
const transferStateResponse = this.transferState.get<any>(stateKey, null);
if (transferStateResponse) {
const response = new HttpResponse({ body: transferStateResponse, status: 200 });
// Remove the response from state transfer, so any future requests to
// the same url go to the network (this avoids us creating an
// implicit/unintentional caching mechanism).
this.transferState.remove(stateKey);
return of(response);
} else {
return next.handle(request);
}
}
}
}
如果你想添加自定义缓存，你可以通过安装来添加memory-cache，但我还没有尝试过。有关更多参考资料，这些文章对我帮助很大，也许它们也可以帮助您。
https://itnext.io/angular-universal-caching-transferstate-96eaaa386198
https://willtaylor.blog/angular-universal-for-angular-developers/
https://bcodes.io/blog/post/angular-universal-relative-to-absolute-http-interceptor
如果没有，您可能需要添加ServerTransferStateModule到您的 app.server.module 文件中。
//app.server.module
import { NgModule } from '@angular/core';
import {
ServerModule,
ServerTransferStateModule
} from "@angular/platform-server";
import { AppModule } from './app.module';
import { AppComponent } from './app.component';
@NgModule({
imports: [
AppModule,
ServerModule,
ServerTransferStateModule
],
bootstrap: [AppComponent],
})
export class AppServerModule {}
祝你好运！