app.component.html

<div *ngFor="let athlete of athletes">
    <span>{{athlete.id}}</span>
    <span>{{athlete.name}}</span>
    <span>{{athlete?.country?.name}}</span>
    <span>{{athlete?.results?.length}}</span>
</div>

app.component.ts

import {Component, OnInit} from '@angular/core';
import {AthleteService} from './services/athlete.service';
import {Athlete} from './model/athlete.model';

@Component({
    selector: 'app-root',
    templateUrl: './app.component.html',
    styleUrls: ['./app.component.css']
})
export class AppComponent implements OnInit {
    private athletes: Athlete[];

    constructor(private athleteService: AthleteService) {
    }

    ngOnInit() {
        this.athleteService.findAll().subscribe(
            athletes => {
                this.athletes = athletes
            },
            error => {
                console.log(error);
            }
        )
    }
}

athlete.model.ts

import {Country} from './country.model';
import {Result} from './result.model';

export class Athlete {
    id: number;
    name: string;
    country: Country;
    results: Result[];
}

athlete.service.ts

import {Injectable} from '@angular/core';
import {Athlete} from '../model/athlete.model';
import {Http, Response} from '@angular/http';
import 'rxjs/add/operator/map'
import 'rxjs/add/operator/catch';
import {Observable} from 'rxjs/Observable';

@Injectable()
export class AthleteService {

    private apiUrl = 'http://localhost:8090/athletes';

    constructor(private http: Http) {
    }

    findAll(): Observable<Athlete[]> {
        return this.http.get(this.apiUrl)
            .map((res: Response) => res.json())
            .catch((error: any) => Observable.throw(error.json().error || 'Server error'));
    }
}

country.model.ts

export class Country {
    id: number;
    name: string;
}

result.model.ts

import {Sport} from './sport.model';

export class Result {
    id: number;
    age: number;
    year: number;
    date: string;
    gold: number;
    silver: number;
    bronze: number;
    sport: Sport;
}