Typescript generic service

Question

I\'m new to typescript and angular2/4 and I\'m building a single app that have two basic entities which is Car and Driver and all I do is to list them with an API call.

Answer 1

You can create an abstract generic class and two children class that inherits from it :

abstract class:

export abstract class AbstractRestService {
  constructor(protected _http: Http, protected actionUrl:string){
  }

  getAll():Observable {
    return this._http.get(this.actionUrl).map(resp=>resp.json() as T[]);
  }
  getOne(id:number):Observable {
    return this._http.get(`${this.actionUrl}${id}`).map(resp=>resp.json() as T);
  }
} 

driver service class

@Injectable()
export class DriverService extends AbstractRestService {
  constructor(http:Http,configuration:Configuration){
    super(http,configuration.serverWithApiUrl+"Driver/");
  }
}

car service class

@Injectable()
export class CarService extends AbstractRestService {
  constructor(http:Http,configuration:Configuration) {
    super(http,configuration.serverWithApiUrl+"Car/");
  }
}

Note that only the concrete classes are marked as @Injectable() and should be declared inside a module while the abstract one should not.

update for Angular 4+

Http class being deprecated in favor of HttpClient, you can change the abstract class to something like that:

export abstract class AbstractRestService {
  constructor(protected _http: HttpClient, protected actionUrl:string){
  }

  getAll():Observable {
    return this._http.get(this.actionUrl) as Observable;
  }

  getOne(id:number):Observable {
    return this._http.get(`${this.actionUrl}${id}`) as Observable;
  }
}