json - Typescript，Angular 2 - 将 Json 解析为 http 中的对象

Question

我有一个文件 location.json，包含以下形式的 JSON 字符串:

{
  "locations": [
    {
      "id": 1,
      "places": [
        {
          "id": 1,
          "city": "A",
          "state": "AB"
        }
      ]
    }
}

我创建了以下形式的类:

export class Location{
       constructor(public id: number,
        public places: Place[],
     }

export class Place {
        constructor(
        public id: number, 
        public city: string,
        public state: string
} 

如何将 JSON 字符串解析为对象？我做了这样的事情:

...
export class DashboardComponent {

  locations: Locations[];

  constructor(private locationService:LocationService) {
    this.getLocations() 
  }

  getLocations(){
      this.locationService.get('assets/location.json')
      .subscribe(res => this.location = res);
  }

Answer 1

根据订阅者的结果，它可以是:

.map(res => this.location = res.json().locations);

或者:

.subscribe(res => this.location = JSON.parse(res).locations);

但请记住，这不会为您的类实例化实例，它只会将值分配为匹配以下内容的常规 js 对象:

interface Location {
    id: number;
    places: Place[];
}

interface Place {
    id: number;
    city: string;
    state: string;
}

如果你想要类的实例，你需要做类似的事情:

JSON.parse(res)
    .locations.map(location => new Location(location.id, 
        location.places.map(place => new Place(place.id, place.city, place.state)))