问题
I have been running my Angular app via ng serve for development and was not experiencing any errors. When using SSR, however, I get an error in my server log whenever I load a component that makes an http request as part of it's ngOnInit method. Is there something wrong with my strategy?
I have not found any useful information from googling my error. Should I be waiting before the page is fully loaded to make my request, or using some other method? If so, how would I do this?
I am using the http-proxy-middleware package to send requests to a django server. https://github.com/chimurai/http-proxy-middleware
This is the error I get when the request is made as part of the ngOnInit:
ERROR Error
at XMLHttpRequest.send (C:\{...}\dist\{...}\server\main.js:201490:19)
at Observable.rxjs__WEBPACK_IMPORTED_MODULE_1__.Observable [as _subscribe] (C:\{...}\dist\{...}\server\main.js:23724:17)
at Observable._trySubscribe (C:\{...}\dist\{...}\server\main.js:186583:25)
at Observable.subscribe (C:\{...}\dist\{...}\server\main.js:186569:22)
at scheduleTask (C:\{...}\dist\{...}\server\main.js:106745:32)
at Observable.rxjs__WEBPACK_IMPORTED_MODULE_7__.Observable [as _subscribe] (C:\{...}\dist\{...}\server\main.js:106807:13)
at Observable._trySubscribe (C:\{...}\dist\{...}\server\main.js:186583:25)
at Observable.subscribe (C:\{...}\dist\{...}\server\main.js:186569:22)
at subscribeToResult (C:\{...}\dist\{...}\server\main.js:196664:23)
at MergeMapSubscriber._innerSub (C:\{...}\dist\{...}\server\main.js:191854:116)
Here is the relevant part of my test component:
export class TestComponent implements OnInit {
output: String = "The server is not running or is not connected"
constructor(private httpTestService: HttpTestService) { }
ngOnInit(): void {
this.testGetRequest();
}
testGetRequest() {
this.httpTestService.testGetRequest().subscribe(temp => {
this.output = temp.message; // response is json with a 'message' attribute
});
}
}
Here is the relevant part of my HttpTestService:
import { HttpClient } from '@angular/common/http';
constructor(private http: HttpClient) { }
testGetRequest(): Observable<any> {
return this.http.get('/api/endpoint1');
}
I believe this part of my server.ts may be important:
import { createProxyMiddleware } from 'http-proxy-middleware';
export function app() {
const server = express();
const distFolder = join(process.cwd(), 'dist/.../browser');
const indexHtml = existsSync(join(distFolder, 'index.original.html')) ? 'index.original.html' : 'index';
server.engine('html', ngExpressEngine({
bootstrap: AppServerModule,
}));
server.set('view engine', 'html');
server.set('views', distFolder);
// re-route requests to /api/ to the django REST api
server.use('/api/**', createProxyMiddleware({ target: 'http://localhost:8000', changeOrigin: true }));
Even when running with SSR, the app functions normally except for the error I get in the server console.
回答1:
You should use absolute URLs when doing HTTP calls. docs
So the problem possibly is here
testGetRequest(): Observable<any> {
return this.http.get('/api/endpoint1');
}
To fix it you can use the interceptor that will change relative URLs to absolute and provide this interceptor inside AppServerModule.
Interceptor is:
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';
@Injectable()
export class UniversalInterceptor implements HttpInterceptor {
constructor(@Optional() @Inject(REQUEST) protected request: Request) {}
intercept(req: HttpRequest<any>, next: HttpHandler) {
let serverReq: HttpRequest<any> = req;
if (this.request && req.url.indexOf('http') !== 0) {
let newUrl = `${this.request.protocol}://${this.request.get('host')}`;
if (!req.url.startsWith('/')) {
newUrl += '/';
}
newUrl += req.url;
serverReq = req.clone({url: newUrl});
}
return next.handle(serverReq);
}
}
AppServerModule is
@NgModule({
imports: [
...
],
bootstrap: [AppComponent],
providers: [
{
provide: HTTP_INTERCEPTORS,
useClass: UniversalInterceptor,
multi: true,
},
],
})
export class AppServerModule {}
Hope it helps
来源:https://stackoverflow.com/questions/61449517/is-there-something-wrong-with-making-an-http-request-in-the-ngoninit-of-a-compon