title: Update ng-select item after added new item from modal in angular 4
body: <p>I need to update ng-select in angular 4 after add new value from modal </p>
  
  <p>In console.log I can view the new added item in list, but it didn't reflect in drop-down</p>
  
  <p>Can any one please suggest</p>
  
  <p>I have following code</p>
  
  <blockquote>
    <p>city.component.ts</p>
  </blockquote>
  
  <p>export class CityComponent implements OnInit {</p>
  
  <pre><code>public myForm: FormGroup; // our model driven form
  
  public city0: Array&lt;any&gt; = [];
  
  constructor(private _fb: FormBuilder) {
  
      this.city0=[ {value:'City A',label:'City A'},
      {value:'City B',label:'City B'},
      {value:'City C',label:'City C'},
      {value:'City D',label:'City D'},];
  
  }
  
  add_new_city(model, isValid: boolean){
  
      this.submitted = true; // set form submit to true
  
      const data = this.newCityForm.value;
      this.city0.push({
      'value': data.new_city_name,
      'label' : data.new_city_name
      });
  
  }
  </code></pre>
  
  <p>}</p>
  
  <blockquote>
    <p>city.component.html</p>
  </blockquote>
  
  <pre><code>&lt;div class="form-group"&gt;
  &lt;label class="col-sm-2 control-label"&gt;City&lt;/label&gt;
  &lt;div class="col-sm-4"&gt;
  
      &lt;ng-select 
          formControlName="city_name"
          [options]="city0"
  
          [multiple]="multiple0"
          [allowClear]="true"
          [(ngModel)]="cityName"
  
          &gt;
      &lt;/ng-select&gt;  
  
  &lt;/div&gt;
  &lt;div class="col-sm-2"&gt;
      &lt;button type="button"(click)="openModal(template)"&gt;Add New City&lt;/button&gt;
  &lt;/div&gt;
  
  &lt;/div&gt;
      &lt;ng-template #template&gt;
          &lt;div class="modal-header"&gt;
              &lt;h4&gt;Add City&lt;/h4&gt;
  
          &lt;/div&gt;
          &lt;div class="modal-body"&gt;
  
              &lt;div class="form-group row"&gt;
                  &lt;label for="new_city_name" &gt;City Name&lt;/label&gt;
                  &lt;div class="col-sm-6"&gt;
                      &lt;input type="text" class="form-control" id="new_city_name" formControlName="new_city_name"&gt;
                  &lt;/div&gt;
              &lt;/div&gt;  
          &lt;/div&gt;
          &lt;div class="modal-footer"&gt;
              &lt;span  class="col-sm-5 "&gt;
                  &lt;button type="button"  (click)="modal.hide()"&gt;Close&lt;/button&gt; 
                  &lt;button type="button"  (click)="add_new_city(newForm.value, newForm.valid)&gt;Save&lt;/button&gt;
              &lt;/span&gt;                                    
          &lt;/div&gt;
      &lt;/ng-template&gt; 
  </code></pre>