运行时错误：未定义锦标赛

Question

该应用程序是使用Ionic 3开发的。我无法从Firebase检索数据。当我尝试用函数调用Api时，它显示错误，表明它没有定义.. 有什么方法可以解决这张照片。此外，ionViewDidUnload在Ionic 3中不起作用。我也尝试使用事件导入，但我还没有得到它。

Tournaments.ts

    import { Component } from '@angular/core';
    import { IonicPage, NavController, NavParams } from 'ionic-angular';

    import { TeamsPage } from '../teams/teams';

    import { EliteApi } from '../../shared/elite-api'

    @IonicPage()
    @Component({
      selector: 'page-tournaments',
      templateUrl: 'tournaments.html',
    })
    export class TournamentsPage {

      tournaments : any;

      constructor(
      public navCtrl: NavController, 
      public navParams: NavParams, 
      private eliteApi : EliteApi) {
      }

      ionViewDidLoad(){
        this.eliteApi.getTournaments().then(data => this.tournaments = data );
      }

      itemTapped($event, tourney){
      this.navCtrl.push(TeamsPage, tourney);
      }

    }

精英api.ts

    import { Injectable } from '@angular/core';
    import { Http, Response } from '@angular/http';

    @Injectable()
    export class EliteApi{

        private baseUrl = 'https://elite-schedule-c1e63.firebaseio.com//';

        constructor(private http: Http){}

        getTournaments(){
            return new Promise(resolve => {
                this.http.get('${this.baseUrl}'/tournaments.json)
                    .subscribe((res: Response) => resolve(res.json()));
            });

        }

    }

Answer 1

错误是因为整个网址应该在`之间（现在/tournaments.json部分不是）。因此，在elite-api.ts文件中，更改getTournaments()方法，如下所示：

    getTournaments(){
        return new Promise(resolve => {
            this.http.get(`${this.baseUrl}/tournaments.json`) // <- Like this :)
                .subscribe((res: Response) => resolve(res.json()));
        });

    }