Utilizing Typescript with Angular 2 to efficiently convert JSON data into objects within HTTP requests

Question

Utilizing Typescript with Angular 2 to efficiently convert JSON data into objects within HTTP requests

I am dealing with a file called location.json, which contains JSON data structured like this:

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

To handle this data, I have created classes as follows:

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

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

My goal is to parse the JSON data into objects. This is what I have tried so far:

...
export class DashboardComponent {

  locations: Locations[];

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

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

json angular parsing typescript angular2-services

Answer 1

Answer №1

Depending on the outcome for the subscriber, it could be:

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

Or:

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

Remember, this will not create instances of your classes, but instead only assign values as regular JavaScript objects that match the following structure:

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

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

If you want instances of the classes, you will need to do something like this:

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

Answer 2

Depending on the outcome for the subscriber, it could be:

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

Or:

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

Remember, this will not create instances of your classes, but instead only assign values as regular JavaScript objects that match the following structure:

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

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

If you want instances of the classes, you will need to do something like this:

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

Answer 3

Answer №2

Typically, when mapping a response in a service method, you would use res => res.json(). However, it's important to ensure that the JSON format is valid, as otherwise it will not be parsed correctly.

Keep in mind that the response itself is an object and cannot be directly parsed - only the body of the response can be parsed.

  return this.http.get(url,options).map((response) => this.parseResponse(response))
        .catch((err) => this.handleError(err));

  private handleError(error: any) {
    let body = error.json();

    return Observable.throw(body);
  }

  private parseResponse(response: Response) {
    return response.json();
  }

Answer 4

Typically, when mapping a response in a service method, you would use res => res.json(). However, it's important to ensure that the JSON format is valid, as otherwise it will not be parsed correctly.

Keep in mind that the response itself is an object and cannot be directly parsed - only the body of the response can be parsed.

  return this.http.get(url,options).map((response) => this.parseResponse(response))
        .catch((err) => this.handleError(err));

  private handleError(error: any) {
    let body = error.json();

    return Observable.throw(body);
  }

  private parseResponse(response: Response) {
    return response.json();
  }

Utilizing Typescript with Angular 2 to efficiently convert JSON data into objects within HTTP requests

Answer №1

Answer №2

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