title: Read the value of <mat-option> angular
body: <p><strong>HTML:</strong></p>
  
  <pre><code>  &lt;mat-icon class="fab fa-raspberry-pi"&gt;&lt;/mat-icon&gt;
    &lt;mat-form-field&gt;
      &lt;mat-select placeholder="Rpi"&gt;
        &lt;mat-option&gt;Choose&lt;/mat-option&gt;
        &lt;mat-option *ngFor='let pi of myRpis' [(ngModel)]="RpiIp" ngDefaultControl [value]="pi.RPI_IP"
          (click)="getPins()"&gt;
          {{pi.LABEL}}
        &lt;/mat-option&gt;
      &lt;/mat-select&gt;
    &lt;/mat-form-field&gt;
  </code></pre>
  
  <p><strong>Typescript:</strong>
  I have:</p>
  
  <pre><code>  RpiIp = '';
  </code></pre>
  
  <p>and </p>
  
  <pre><code>  getPins() {
      console.log(this.RpiIp);
      this.doneFetching = true;
    }
  </code></pre>
  
  <p>The console prints an empty value (the value do not change). Where is the error? why the value is not changing?</p>