title: Get values from a group of Angular Material checkboxes?
body: <p>I'm trying to figure out how to get the selected values of a group of Angular (7) Material checkboxes.</p>
  
  <p>Let's say I have an area on the form "flavors" and 3 checkboxes with values of "chocolate", "vanilla", and "strawberry".</p>
  
  <pre><code>&lt;h3&gt;Flavors&lt;/h3&gt;
  &lt;mat-checkbox value="chocolate"&gt;Chocolate&lt;/mat-checkbox&gt;
  &lt;mat-checkbox value="vanilla"&gt;Vanilla&lt;/mat-checkbox&gt;
  &lt;mat-checkbox value="strawberry"&gt;Strawberry&lt;/mat-checkbox&gt;
  </code></pre>
  
  <p>As the checkboxes are checked on and off, I want to update the variable (model) "flavorsAvailable".</p>
  
  <p>It's simple to do this with mat-radio-groups, since it's just an ngModel on the group element.  But how do I manage checkboxes?</p>
  
  <p>Note:  I don't want to use an Angular Material Selection list; this is just for forms.</p>