title: Search object by ID inside JSON file using Angular 2+
body: <p>I have a JSON file like this one, sumarizing: </p>
  
  <pre><code>{
      "id": "1",
      "country": "Brazil",
      "state": [
          {"id": "1", "name": "Acre", 
              "city": [ { "id": "1", "name": "Rio Branco"}, 
                        { "id": "2", "name": "Xapuri"}, 
                        { "id": "3", "name": "Cruzeiro do Sul"} ] 
  }
  </code></pre>
  
  <p>I've created a 3 select options in a view, I have to select first the country, then based on the country ID, I need to fill the second select option with the states. After select the state, I need to fill the third select option with the cities. </p>
  
  <p>I've created the PlacesService that return all JSON file:</p>
  
  <pre><code>  getPlaces() {
      return this.http.get('assets/database/places.json')
      .map( (res: Response) =&gt; res.json());
    }
  </code></pre>
  
  <p>Then in my component I call this service and works well:</p>
  
  <pre><code>this.placesService.getPlaces().subscribe(dados =&gt; this.places= dados);
  </code></pre>
  
  <p>Ok, I know how to return all data of JSON file, but I don't know how search a specific id inside of JSON file and returns only the object related of these ID. </p>
  
  <p>I would like to know how solve this problem and what is the best practice, use all objects inside a unique json file or divide in others json files (ex: countries.json, states.json, cities.json)</p>