我這幾天一直有問(wèn)題。我正在嘗試使用對(duì) JSON API 的查詢結(jié)果填充對(duì)象。我需要填寫(xiě)一個(gè)模型，因?yàn)橥ㄟ^(guò)它我需要釘一個(gè)鍵來(lái)在另一個(gè) api 中進(jìn)行另一個(gè)查詢并在屏幕上返回?cái)?shù)據(jù)。但到目前為止我能得到的都是未定義的為了更好地理解我需要填充生成對(duì)象，以便通過(guò)它我可以填充另一個(gè)對(duì)象的數(shù)據(jù)并獲取一個(gè) url 來(lái)查詢另一個(gè)端點(diǎn) api 并從屏幕返回其他數(shù)據(jù)。export class PokeApp implements OnInit  {   gen1: Generation[];   gen2: Generation[];    generation : Generation;  constructor(private http: HttpClient, private gService:GenerationService) {  }  ngOnInit(){   this.getGeneration1();   this.getGeneration2();   // Only for test, this is not the data ho i need - but this object generation returns null, i do not now how.   this.gService.getPokemon_Species(this.generation.name);  }// this request return a gen1 object to my screen, but a need this object in JS code// to do another query.  getGeneration1(): void{    this.gService.getGeneration1().subscribe(gen =>{    this.gen1 = gen    this.generation = gen[0];  });  }  getGeneration2(): void{    this.gService.getGeneration2().subscribe(gen => this.gen2 = gen);    console.log("Still Returned Undefined___>>>>" + this.generation); }// this do the request to a Poke APIexport class GenerationService {  private GetGenerationURL1 = "https://pokeapi.co/api/v2/generation/1";  private GetGenerationURL2 = "https://pokeapi.co/api/v2/generation/2";  httpOptions = { headers: new HttpHeaders({ "Content-Type": "application/json" }) };  constructor(private http: HttpClient) { }  getGeneration1(): Observable<Generation[]> {    return this.http.get<Generation[]>(this.GetGenerationURL1)      .pipe(        tap(_ => console.log('fetched generations')),        catchError(this.handleError<Generation[]>('getGeneration1', []))      );    // Subscribe to begin listening for async result  }  getGeneration2(): Observable<Generation[]> {    return this.http.get<Generation[]>(this.GetGenerationURL2)    .pipe(      tap(_ => console.log('fetched generations')),      catchError(this.handleError<Generation[]>('getGeneration2', []))    );  }