Angular 使用从服务器请求的值来创建类的实例

我想创建包含自定义类的类

这里我的类是客户，它包含的自定义类是国家

对于国家，我有以下类别：

export class Country {
    constructor(public shortcut: string, public description: string) { }
}

我从国家/地区服务获得国家/地区列表

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

import { Observable } from 'rxjs/Observable';
import 'rxjs/add/observable/of';
import 'rxjs/add/operator/map';

import { Country } from './country';

@Injectable()
export class CountryService {

  countries: Country[];

  constructor(private http: Http) {
    this.getCountries().subscribe();
   }

  getCountries(): Observable<any> {
    if(this.countries != null) {
      return Observable.of(this.countries)
    } else {
      return this.http.get(`http://my-json-server.typicode.com/kolomu/CustomerDemoApp/countries`, { method: 'Get'})
      .map( (response) => response.json() )
      .map( (countries) => this.countries = countries)
    }
  }

  getDescription(shortcut: string): Observable<string> {
    if(this.countries != null) {
      let tempCountry = this.countries.find( (e) => e.shortcut == shortcut);
      return Observable.of(tempCountry.description);
    } else {
      this.getCountries().subscribe(
        (countries) => {
          let tempCountry = this.countries.find( (e) => e.shortcut == shortcut);
          return Observable.of(tempCountry.description);
        }
      );
    }

  }

}

我的问题是，不知何故，措辞和方法调用不再有意义

请参阅下面的Customer类，了解我如何在getDescription调用中创建国家/地区

import { AppInjector } from './app-injector';
import { Country } from './country';
import { CountryService } from './country.service';

export class Customer {

    public country: Country;
    public countryService: CountryService;

    constructor(public name: string, public countryShortcut: string){
        this.countryService = AppInjector.get(CountryService);


        this.countryService.getDescription(countryShortcut).subscribe(
            countryDescription => {
                return new Country(countryShortcut, countryDescription)
            } 
        )

    }


}

我的思维错误在哪里？也许用我自己的国家/地区实例创建客户的整个过程是错误的？非常感谢您的帮助

下面是该项目的github回购协议。 一些事情

使用httpClient，而不是http。因此，您不需要使用response.json（）

如果您想订阅返回数组的可观察对象，请使用Observable 3.-映射更改响应。如果您想对响应执行某些操作，请使用do

L

在我看来，您不需要类，只需要接口（类中没有方法）

import { AppInjector } from './app-injector';
import { Country } from './country';
import { CountryService } from './country.service';

export class Customer {

    public country: Country;
    public countryService: CountryService;

    constructor(public name: string, public countryShortcut: string){
        this.countryService = AppInjector.get(CountryService);


        this.countryService.getDescription(countryShortcut).subscribe(
            countryDescription => {
                return new Country(countryShortcut, countryDescription)
            } 
        )

    }


}

getCountries(): Observable<any[]> { //<--return an array
    if(this.countries != null) {
      return Observable.of(this.countries);
    } else {
      return this.http.get(`http://my-json-server.typicode.com/kolomu/CustomerDemoApp/countries`)  //we don't need json because we use httpClient
                        //If use "get" not put "method get"
    .do((result)=>this.countries=result); //use "do" to do something more with the response. do NOT change the response
}

getDescription(shortcut: string): Observable<string> {
    if(this.countries != null) {
      let tempCountry = this.countries.find( (e) => e.shortcut == shortcut);
      return Observable.of(tempCountry.description);
    } else {
      this.getCountries().map( //If not work try switchMap instead map
        (countries) => {
          let tempCountry = this.countries.find( (e) => e.shortcut == shortcut);
          return tempCountry.description; //not Observable.of
        }
      );
    }

this.country=new Country(...)