未定义类型不能分配给[电影]类型

Question

I am learning how to make http request in angular using service and here is my code:

export class ApiCallService {
    // DECLARATIONS:
    tmdb_api_key = '*******'; // personal api key to access the TMDB API
    posterBaseAddress = 'https://image.tmdb.org/t/p/w300'; // base 
    address of the TMDB poster link, to add film specific path
   // SEARCH PARAMETERS
   requestPages: number; // get the number of pages for the request so is possible to load all the films (request is 1 page at time)
    pageToLoad = 1; // number of page to load, start with 1
    baseLanguage = 'en-US'; // return film in english, search can be done in local language but return english titles
    foundFilms: [Film] = [];

constructor(private http: Http) {}
// TODO: GET method to search for film

getFilmsByTitle(filmTitle: string, page: number) {
    // if the search has only 1 page will be 1 otherwise will load the films on the respective page
    this.pageToLoad = page;
    return this.http.get('https://api.themoviedb.org/3/search/movie?' +
    'api_key=*******$' +
    '&language=' + this.baseLanguage +
    '&query=' + filmTitle +
    '&page=' + this.pageToLoad +
    '&include_adult=false')
        .map(
            (response: Response) => {
                const films = response.json();
                for (const film of films['results']) {
                    const singleFilm = new Film(film.title, film.overview, film.release_date, film.poster_path, film.genre_ids);
                    this.foundFilms.push(singleFilm);
                }
                this.requestPages = films.total_pages;
                return this.foundFilms;
            }
        );
}
}


export class AppComponent implements OnInit {

constructor(private apiCallService: ApiCallService) {}

 ngOnInit() {
   this.apiCallService.getFilmsByTitle('Harry', 1).subscribe(
  (films: [any]) => {
    console.log(films);
  }
);
  }
}

When I launch the app I get this error, ERROR in src/app/services/apicall.service.ts(15,5): error TS2322: Type 'undefined[]' is not assignable to type '[Film]'. Property '0' is missing in type 'undefined[]'.

And in the console I have this error: Cannot read property 'push' of undefined

I don't understand why, i tried several was to declare the foundFilms array but I cannot make it work.

I hope someone can help

Thanks Alessandro

Answer 1

声明数组时，需要对其进行初始化。

foundFilms: Film[] = [];