### Template Angular

      <div class="col">
        <fieldset ngModelGroup="categories">
          <select multiple [ngModel]="news?.categories" name="categories">
            <option *ngFor="let cat of categories"
            [value]="cat"
            >{{cat?.name}}</option>
          </select>
        </fieldset>
      </div>


### MODEL

"news": [
        {
            "id": 1,
            "title": "titolo della news",
            "body": "Maecenas ultricies enim a diam ornare ultricies. Nam auctor sem ac ullamcorper auctor. Suspendisse dignissim turpis vitae eros ultricies semper. Nullam ex lectus, lobortis sed ultricies id, gravida in nisl. Sed rhoncus metus suscipit tincidunt scelerisque. Sed turpis nibh, mollis eu augue vitae, aliquet semper massa. Nullam in ipsum egestas, ultrices tellus ac, varius est. Cras commodo, sapien quis elementum dignissim, nisl nisi dapibus lacus, et posuere ex dolor sit amet elit. Mauris id metus sed tortor tristique fermentum non sed augue. Phasellus interdum felis vel neque laoreet, nec sodales augue lobortis. Donec eget eros at elit bibendum pharetra venenatis nec nunc. Sed vel feugiat ex, quis scelerisque metus. Ut bibendum a velit sit amet semper. Mauris elementum egestas molestie. Cras at dui luctus, tristique ligula mattis, bibendum tellus. Donec suscipit quam ipsum, euismod iaculis mi scelerisque sed.",
            "enti": [
                {
                    "id": 2,
                    "name": "Comune di riferimento"
                }
            ],
            "categories": [
                {
                    "id": 1,
                    "name": "News"
                },
                {
                    "id": 2,
                    "name": "Informazioni"
                }
            ],
            "attachments": [
                {
                    "id": 1,
                    "path": "https://picsum.photos/300/200/?random",
                    "size": 2048,
                    "created_at": "2015-08-05T08:40:51.620Z"
                }, {
                    "id": 2,
                    "path": "https://picsum.photos/300/200/?random",
                    "size": 1024,
                    "created_at": "2015-08-05T08:40:51.620Z"
                }, {
                    "id": 3,
                    "path": "https://picsum.photos/300/200/?random",
                    "size": 512,
                    "created_at": "2015-08-05T08:40:51.620Z"
                }, {
                    "id": 4,
                    "path": "https://picsum.photos/300/200/?random",
                    "size": 256,
                    "created_at": "2015-08-05T08:40:51.620Z"
                }
            ],
            "user": [
                {
                    "id": 1,
                    "username": "Admin"
                }
            ],
            "created_at": "2015-08-05T08:40:51.620Z",
            "modified_at": "2015-08-05T08:40:51.620Z"
        }