我想嘗試從 json 文件 url 加載國家：https : //raw.githubusercontent.com/sagarshirbhate/Country-State-City-Database/master/Contries.json 到 angular2-multiselect。下面是我的代碼getCountries(){this.country.allCountries().subscribe(    data2 => {      this.countryInfo = data2.Countries.CountryName;      console.log('Data:', this.countryInfo);    },    err => console.log(err),    () => console.log('complete') )}所以 getcountry 函數從我用這里的 url 創建的服務獲取數據就是服務  export class CountriesService {  url: string = "https://raw.githubusercontent.com/sagarshirbhate/Country-State-City-   Database/master/Contries.json";  constructor(private http: HttpClient) { } allCountries(): Observable<any>{  return this.http.get(this.url); } }此顯示數據：在控制臺日志中未定義。請幫我解決