title: How can i set properties of component in angular
body: <p>I am playing around with some custom component in Angular and are wondering if there is a way to achieve the following. I have a form which i want to dynamically
  show or hide different form elements in an reactive form. On normal inputs that is not an issue but i have several instances of a custom control which i set in template like this.</p>
  
  <pre><code>&lt;app-dropdown placeholder="Test"
  [disabled]="showEditNewButton"
  guid='820E04E0-8084-4D9C-A268-D8C0D21E74F6'
  formControlName="test"&gt;
  &lt;/app-dropdown&gt; 
  </code></pre>
  
  <p>So the question now is how can i via code in the component of the parent can set the placeholder string or the guid ? Also what is the best way to hide or remove certain custom controls from Dom based on a value in another field on the reactive form. Keep in mind there might be multiple instances of this same component just with different formControlName and guid.</p>
  
  <p>I have in my component already specified @Input() so i can send data from template to component.</p>
  
  <pre><code>  @Input() guid: string;
    @Input() options: IServerDropdownOption[];
    @Input() placeholder = '--Select--';
    @Input() isRequired = false;
  
    private _disabled = false;
    @Input() set disabled(isDisabled: boolean) {
        this._disabled = isDisabled;
    };
    get disabled() {
        return this._disabled;
    }
  
    options$: Observable&lt;Array&lt;ServerDropdownOption&gt;&gt;;
    value;
    selectField;
    form: FormGroup;
    onChange;
    onTouched;
    validateFn: Function;
  </code></pre>
  
  <p>The question is how can i send data to the child component from the parent component like i want to via code to set the placeholder.</p>