title: Protractor how to get all child elements from parent element
body: <p>Hi I have following html for radio buttons. I am trying to get the list of child elements for the parent element using by.model and iterate through them and select the radio buttons. I tried the following code but it says no element found</p>
  
  <pre><code>var drilldownRadios = element(by.model('filterParameters.rptGrping')).$$("md-radio-button");
  </code></pre>
  
  <p>the HTML code from the app</p>
  
  <pre><code>&lt;md-radio-group layout="row" ng-model="filterParameters.rptGrping" class="ng-pristine ng-valid _md layout-row ng-not-empty ng-touched" role="radiogroup" tabindex="0" aria-invalid="false" aria-activedescendant="radio_2722" style=""&gt;
     &lt;md-radio-button value="National" id="radio_2720" role="radio" aria-checked="false" aria-label="National"&gt;
        &lt;div class="md-container" md-ink-ripple="" md-ink-ripple-checkbox=""&gt;
           &lt;div class="md-off"&gt;&lt;/div&gt;
           &lt;div class="md-on"&gt;&lt;/div&gt;
        &lt;/div&gt;
        &lt;div ng-transclude="" class="md-label"&gt;
           &lt;filtertext class="ng-scope"&gt;National&lt;/filtertext&gt;
        &lt;/div&gt;
     &lt;/md-radio-button&gt;
     &lt;!-- ngIf: !$ctrl.reportInfo.authRoleClasses.studentInfo --&gt;
     &lt;md-radio-button ng-if="!$ctrl.reportInfo.authRoleClasses.studentInfo" ng-click="$ctrl.setSelectedStates()" class="stateRadio ng-scope md-checked" value="State" role="radio" tabindex="0" id="radio_2722" aria-checked="true" aria-label="California" style=""&gt;
        &lt;div class="md-container" md-ink-ripple="" md-ink-ripple-checkbox=""&gt;
           &lt;div class="md-off"&gt;&lt;/div&gt;
           &lt;div class="md-on"&gt;&lt;/div&gt;
        &lt;/div&gt;
        &lt;div ng-transclude="" class="md-label"&gt;
           &lt;filtertext class="ng-binding ng-scope"&gt;California&lt;/filtertext&gt;
        &lt;/div&gt;
     &lt;/md-radio-button&gt;
     &lt;!-- end ngIf: !$ctrl.reportInfo.authRoleClasses.studentInfo --&gt;
     &lt;!-- ngIf: $ctrl.reportInfo.authRoleClasses.studentInfo --&gt;
     &lt;!-- ngIf: !$ctrl.reportInfo.authRoleClasses.studentInfo --&gt;
     &lt;md-radio-button value="District" ng-click="$ctrl.setSelectedStates()" ng-if="!$ctrl.reportInfo.authRoleClasses.studentInfo" class="ng-scope" role="radio" tabindex="0" id="radio_2723" aria-checked="false" aria-label="California and District(s)" style=""&gt;
        &lt;div class="md-container" md-ink-ripple="" md-ink-ripple-checkbox=""&gt;
           &lt;div class="md-off"&gt;&lt;/div&gt;
           &lt;div class="md-on"&gt;&lt;/div&gt;
        &lt;/div&gt;
        &lt;div ng-transclude="" class="md-label"&gt;
           &lt;filtertext class="ng-binding ng-scope"&gt;California and District(s)&lt;/filtertext&gt;
        &lt;/div&gt;
     &lt;/md-radio-button&gt;
     &lt;!-- end ngIf: !$ctrl.reportInfo.authRoleClasses.studentInfo --&gt;
  &lt;/md-radio-group&gt;
  </code></pre>