如何在Angular8中制作通用请求服务

Question

我已经创建了通用请求服务，但它一直返回“ ZoneAwarePromise”。我尝试使用.pipe（）和.subscribe（）尝试检索请求的内容，但是它不起作用。

requester.service.ts

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';

@Injectable({
  providedIn: 'root'
})
export class RequesterService {

  constructor(private http: HttpClient) { }

  request(method, url, headers, body, params) {
    return this.http.request(method, url, {
      body: body || {},
      headers: headers || {},
      params: params || {}
    })
  }

  async get(url, params?, headers?, data?) {
    return await this.request('get', url, params, headers, data)
  }

  async post(url, params, headers, data) {
    return await this.request('post', url, params, headers, data);
  }

  async put(url, params, headers, data) {
    return await this.request('put', url, params, headers, data);
  }

  async delete(url, params, headers, data) {
    return await this.request('delete', url, params, headers, data);
  }
}

gym-list.component.ts

import { Component, OnInit } from '@angular/core';
import { RequesterService } from 'src/app/core/Requester/requester.service';

@Component({
  selector: 'app-gym-list',
  templateUrl: './gym-list.component.html',
  styleUrls: ['./gym-list.component.css']
})
export class GymListComponent implements OnInit {

  constructor(private Requester: RequesterService) { }

  ngOnInit() {
    console.log(this.teste())
  }

  async teste() {
    await this.Requester.get('https://searchs.glitch.me/proposalcontent')
  }
}

Answer 1

您正在尝试通过await返回非异步函数。

Private Sub RichTextBox1_KeyPress(sender As Object, e As KeyPressEventArgs) Handles RichTextBox1.KeyPress

    If Asc(e.KeyChar) = 13 Then

        e.Handled = True

    End If

End Sub

您不应在此处使用异步等待系统。

尝试一下：

  request(method, url, headers, body, params) {
    return this.http.request(method, url, {
      body: body || {},
      headers: headers || {},
      params: params || {}
    })
  }

  async get(url, params?, headers?, data?) {
    return await this.request('get', url, params, headers, data)
  }

并在您的component.ts文件中订阅此方法。

赞：

  get(url, params?, headers?, data?) {
    return this.request('get', url, params, headers, data)
  }

Answer 2

import { HttpClient, HttpHeaders, HttpRequest, HttpEventType, HttpEvent, HttpResponse, HttpErrorResponse } from "@angular/common/http";
import { Observable, from } from 'rxjs';
import { IGenericHttpClient } from './igeneric-http-client';
import { Injectable } from '@angular/core';
import { HttpMethod } from '../view-models/component-type.enum'
import { IRequestOptions } from '../view-models/interface';
import { EnvironmentViewModel } from '../view-models/environment-view-model';
import { retry } from 'rxjs/operators';
@Injectable()
export class GenericHttpClient<T> implements IGenericHttpClient<T>{

  constructor(private httpClient: HttpClient, private environment: EnvironmentViewModel) { }

  public Post(destinationUrl: string, options?: IRequestOptions): Observable<T> {
    return this.request<T>(HttpMethod.Post, destinationUrl, options);
  }

  public Put(destinationUrl: string, options?: IRequestOptions): Observable<T> {
    return this.request<T>(HttpMethod.Put, destinationUrl, options);
  }

  public Get(destinationUrl: string, options?: IRequestOptions): Observable<T> {
    return this.request<T>(HttpMethod.Get, destinationUrl, options);
  }

  public Delete(destinationUrl: string, options?: IRequestOptions): Observable<T> {
    return this.request<T>(HttpMethod.Delete, destinationUrl, options);
  }

  private request<T>(method: string, url: string, options?: IRequestOptions): Observable<T> {
    return Observable.create((observer: any) => {
      this.httpClient.request<T>(new HttpRequest(method, this.environment.baseUrl + url, options)).subscribe(
        (response: any) => {
          const responsTye = response as HttpEvent<any>
          switch (responsTye.type) {
            case HttpEventType.Sent:
              console.log('Request sent!');
              break;
            case HttpEventType.ResponseHeader:
              console.log('Response header received!');
              break;
            case HttpEventType.DownloadProgress:
              const kbLoaded = Math.round(responsTye.loaded / 1024);
              console.log(`Download in progress! ${kbLoaded}Kb loaded`);
              break;
            case HttpEventType.Response:
              observer.next(response.body);
              console.log('? Done!', responsTye.body);
          }
        },
        (error) => {
          switch (error.status) {
            case 403:
              observer.complete();
              break;
            default:
              observer.error(error);
              break;
          }
        }
      );
    });
  }
}

Answer 3

实际上，您可以创建可以在任何服务中扩展的抽象基础服务类。这将通过调用另一个具有通用错误处理代码的服务来自动处理错误。如果传递customError标志，则错误将返回到组件中以处理自定义错误。此方法使用RxJs Observables，可以在component.ts中进行订阅并捕获响应和错误。

import { HttpClient, HttpHeaders } from "@angular/common/http";
import { Observable } from "rxjs";
import { tap } from "rxjs/operators";

import { HttpOptionsService } from "../../services/httpoptions.service";

export abstract class ServiceBase {
  constructor(
    private http: HttpClient,
    private httpOptionService: HttpOptionsService
  ) {}

  httpOptions = {
    headers: new HttpHeaders({
      "Content-Type": "application/json"
    })
  };

  getFormattedPostRequest(
    url: string,
    body: any,
    customError: boolean = false): Observable<any> {
    return this.pipeTapObservable(
      this.http.post(url, body, this.httpOptions),
      customError
    );
  }

  getFormattedPutRequest(
    url: string,
    body: any,
    customError: boolean = false
  ): Observable<any> {
    return this.pipeTapObservable(
      this.http.put(url, body, this.httpOptions),
      customError
    );
  }

  getFormattedGetRequest(
    url: string,
    customError: boolean = false
  ): Observable<any> {
    return this.pipeTapObservable(
      this.http.get(url, this.httpOptions),
      customError
    );
  }

  getFormattedDeleteRequest(
    url: string,
    customError: boolean = false
  ): Observable<any> {
    return this.pipeTapObservable(
      this.http.delete(url, this.httpOptions),
      customError
    );
  }

  private pipeTapObservable(
    request: Observable<any>,
    customError: boolean = false
  ): Observable<any> {
    return request.pipe(
      tap(
        response => response,
        error => {
          !customError &&
            this.httpOptionService.handleError(error);
          return error;
        }
      )
    );
  }
}

如果要添加一些常见的标头，则可以创建一个拦截器来添加它们。您可以在以下任何服务中使用它。

 @Injectable()
    export class MyService extends ServiceBase {
      constructor(
        http: HttpClient,
        httpOptionService: HttpOptionsService
    ) {
        super(http, httpOptionService);
      }
   }

Answer 4

您可以使用async / await，但是此语法适用于promise类型和request方法，返回一个可观察的值，因此您只需要从request方法返回一个promise，或者可以在get，post，put，删除方法

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';

@Injectable({
  providedIn: 'root'
})
export class RequesterService {

  constructor(private http: HttpClient) { }

  request(method, url, headers, body, params) {
    return this.http.request(method, url, {
      body: body || {},
      headers: headers || {},
      params: params || {}
    }).toPromise();
  }

   get(url, params?, headers?, data?) {
    return this.request('get', url, params, headers, data);
  }

   post(url, params, headers, data) {
    return this.request('post', url, params, headers, data);
  }

   put(url, params, headers, data) {
    return this.request('put', url, params, headers, data);
  }

   delete(url, params, headers, data) {
    return this.request('delete', url, params, headers, data);
  }
}

组件

import { Component, OnInit } from '@angular/core';
import { RequesterService } from 'src/app/core/Requester/requester.service';

@Component({
  selector: 'app-gym-list',
  templateUrl: './gym-list.component.html',
  styleUrls: ['./gym-list.component.css']
})
export class GymListComponent implements OnInit {

  constructor(private Requester: RequesterService) { }

  ngOnInit() {
    console.log(this.teste())
  }

  async teste() {
    const result = await this.Requester.get('https://searchs.glitch.me/proposalcontent');

    console.log(result); ?
  }
}