title: How can I check number of elements on a select list and disable radio button?
body: <p>I would like to:</p>
  
  <ul>
  <li>disable radio button (with name 'advertisementType') when select list (with name 'updateAdvertisement') has got only 1 element</li>
  <li>disable submit button (with name 'saveButton') when selected option on select list has got null value</li>
  </ul>
  
  <p>How can I do that in angular?</p>
  
  <p>This is my html:</p>
  
  <pre><code>&lt;div ng-controller="AdvertisementCtrl"&gt;
      &lt;form ng-submit="save()"&gt;
  
          &lt;input type="radio" ng-model="advertisementType" name="advertisementType" value="false"&gt;Update&lt;br /&gt;
  
          &lt;select ng-model="updateAdvertisement" name="updateAdvertisement" ng-show="advertisementType == 'false'"&gt;
              &lt;option value&gt;Select item&lt;/option&gt;
              &lt;option value="1"&gt;Volvo&lt;/option&gt;
              &lt;option value="2"&gt;Saab&lt;/option&gt;
              &lt;option value="3"&gt;Mercedes&lt;/option&gt;
              &lt;option value="4"&gt;Audi&lt;/option&gt;
          &lt;/select&gt;
  
          &lt;input type="submit" value="Save" name="saveButton" ng-disabled="saveButton" /&gt;
  
      &lt;/form&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>This is my javascript (but I have no idea):</p>
  
  <pre><code>&lt;script&gt;
      function AdvertisementCtrl($scope) {
  
      }
  &lt;/script&gt;
  </code></pre>