如何使用Get()来查看以角表示的响应

Question

我很难在页面上实现API调用，并且想知道订阅/观察方法出了什么问题，现在我有以下代码：

import { Component, OnInit } from '@angular/core';
    import { Router } from '@angular/router';
    import { appRoutesNames } from 'src/app/app.routes.names';
    import { coachInteractionRouteNames } from '../coach-integration.routes.names';
    import { createSessionRouteNames } from '../create-session/create-session.routes.names';
    import { coachMatchMakingRouteNames } from './coach-matchmaking.routes.names';
    import { CoachGenericResponse,SupportAreaCategory } from './coach-matchmaking.model';
    import { HttpClient } from '@angular/common/http';
    
    @Component({
      selector: 'app-coach-matchmaking',
      templateUrl: './coach-matchmaking.component.html',
      styleUrls: ['./coach-matchmaking.component.scss']
    })
    export class CoachMatchmakingComponent implements OnInit {
      appService: any;
      coachService: any;
      supportAreas: any;
      http: any;
    
      constructor(private readonly router: Router, http: HttpClient) { }
    
         
      ngOnInit(): void {
        this.getCategories().subscribe;
      }
    
      
    
      //API Loading
    
    private userAccessURL = "https://uks-tst-tbp-gw.azurewebsites.net/Business/GetCategories";
    
    getCategories = () => {
      return this.http.get(this.userAccessURL);
    }
    
    }

但是页面的控制台/网络区域中没有任何东西，所以看起来根本没有API正在加载，有人能帮上忙吗？

Answer 1

  this.getCategories().subscribe(res=>{console.log('GetCategories Resoibse',res)})

Answer 2

我建议阅读rxjs和可观察的工作原理，因为您将经常在角度上使用它们。在您的特定示例中，您需要执行以下操作才能订阅：

ngOnInit() {
    this.getCategories().subscribe((data) => {
        // data contains your API response
    });
}

或者，如果你更喜欢与承诺合作，你可以将你的可观察到的承诺转化为承诺，如下所示：

import { lastValueFrom } from 'rxjs';

//...

ngOnInit() {
    lastValueFrom(this.getCategories()).then((data) => {
        // data contains your API response
    });
}