Angular Learning Chat Http (Error Handling/Request Intercepting)-JS Tutorial-php.cn

Angular Learning Chat Http (Error Handling/Request Intercepting)

青灯夜游

Release： 2022-12-16 19:36:15

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This article will take you to continue learning angular, briefly understand Http processing in Angular, and introduce error handling and request interception. I hope it will be helpful to everyone!

Angular Learning Chat Http (Error Handling/Request Intercepting)

Basic use

Using the HttpClient provided by Angular, you can easily access the API interface. [Related tutorial recommendations: "angular tutorial"]

For example, create a new http.service.ts, which can be configured differently in environment The host address of the environment

Post it againproxy.config.json It was introduced in Chapter 1

{
  "/api": {
    "target": "http://124.223.71.181",
    "secure": true,
    "logLevel": "debug",
    "changeOrigin": true,
    "headers": {
      "Origin": "http://124.223.71.181"
    }
  }
}

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import { HttpClient } from &#39;@angular/common/http&#39;;
import { Injectable } from &#39;@angular/core&#39;;
import { environment } from &#39;@env&#39;;

@Injectable({ providedIn: &#39;root&#39; })
export class HttpService {
  constructor(private http: HttpClient) {}

  public echoCode(method: &#39;get&#39; | &#39;post&#39; | &#39;delete&#39; | &#39;put&#39; | &#39;patch&#39; = &#39;get&#39;, params: { code: number }) {
    switch (method) {
      case &#39;get&#39;:
      case &#39;delete&#39;:
        return this.http[method](`${environment.backend}/echo-code`, { params });
      case &#39;patch&#39;:
      case &#39;put&#39;:
      case &#39;post&#39;:
        return this.http[method](`${environment.backend}/echo-code`, params);
    }
  }
}

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Then we can use it like this in business

import { Component, OnInit } from &#39;@angular/core&#39;;
import { HttpService } from &#39;./http.service&#39;;

@Component({
  selector: &#39;http&#39;,
  standalone: true,
  templateUrl: &#39;./http.component.html&#39;,
})
export class HttpComponent implements OnInit {
  constructor(private http: HttpService) {}
  ngOnInit(): void {
    this.http.echoCode(&#39;get&#39;, { code: 200 }).subscribe(console.log);
    this.http.echoCode(&#39;post&#39;, { code: 200 }).subscribe(console.log);
    this.http.echoCode(&#39;delete&#39;, { code: 301 }).subscribe(console.log);
    this.http.echoCode(&#39;put&#39;, { code: 403 }).subscribe(console.log);
    this.http.echoCode(&#39;patch&#39;, { code: 500 }).subscribe(console.log);
  }
}

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This looks very simple and similarAxios

Here are some common usages

Error handling

this.http
  .echoCode(&#39;get&#39;, { code: 200 })
  .pipe(catchError((err: HttpErrorResponse) => of(err)))
  .subscribe((x) => {
    if (x instanceof HttpErrorResponse) {
      // do something
    } else {
      // do something
    }
  });

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Request interception

Request interception is more commonly used

For example, you can determine whether the cookie is valid/global error handling here...

New http-interceptor.ts File (the file name can be arbitrary)

The most important thing is to implement the intercept method of HttpInterceptor

import { HttpInterceptor, HttpRequest, HttpHandler, HttpResponse, HttpErrorResponse } from &#39;@angular/common/http&#39;;
import { Injectable } from &#39;@angular/core&#39;;
import { Observable, of, throwError } from &#39;rxjs&#39;;
import { filter, catchError } from &#39;rxjs/operators&#39;;
import { HttpEvent } from &#39;@angular/common/http&#39;;

@Injectable()
export class HttpInterceptorService implements HttpInterceptor {
  constructor() {}
  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    return next
      .handle(req)
      .pipe(filter((event) => event instanceof HttpResponse))
      .pipe(
        catchError((error) => {
          console.log(&#39;catch error&#39;, error);
          return of(error);
        })
      );
  }
}

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Then use this interceptor in the providers in the module to take effect

@NgModule({
  imports: [RouterModule.forChild(routes)],
  exports: [RouterModule],
  providers: [
    {
      provide: HTTP_INTERCEPTORS,
      useClass: HttpInterceptorService,
      multi: true,
    },
  ],
})
export class XXXModule {}

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