title: vaadin-grid selection not working
body: <p>The row selection is not working for me. The selectedItems array only changes if I select everything at once. I am not sure if I got something wrong or if that is a bug.</p>
  
  <blockquote>
    <p>selectedItems: An array that contains the selected items.
    <a href="https://www.webcomponents.org/element/vaadin/vaadin-grid/elements/vaadin-grid" rel="nofollow noreferrer">https://www.webcomponents.org/element/vaadin/vaadin-grid/elements/vaadin-grid</a></p>
  </blockquote>
  
  <pre><code>&lt;link rel="import" href="../bower_components/polymer/polymer-element.html"&gt;
  
  &lt;link rel="import" href="../bower_components/vaadin-grid/vaadin-grid.html"&gt;
  &lt;link rel="import" href="../bower_components/vaadin-grid/vaadin-grid-selection-column.html"&gt;
  
  &lt;dom-module id="schedule-vaadin-test"&gt;
  
      &lt;template&gt;
  
          &lt;vaadin-grid id="material" aria-label="Array Data Example" items="[[items]]" selected-items="{{selectedItems}}"&gt;
  
              &lt;vaadin-grid-selection-column auto-select&gt;
              &lt;/vaadin-grid-selection-column&gt;
  
              &lt;vaadin-grid-column width="50px" flex-grow="0"&gt;
                  &lt;template class="header"&gt;#&lt;/template&gt;
                  &lt;template&gt;[[index]]&lt;/template&gt;
              &lt;/vaadin-grid-column&gt;
  
              &lt;vaadin-grid-column&gt;
                  &lt;template class="header"&gt;First Name&lt;/template&gt;
                  &lt;template&gt;[[item.firstName]]&lt;/template&gt;
              &lt;/vaadin-grid-column&gt;
  
              &lt;vaadin-grid-column&gt;
                  &lt;template class="header"&gt;Last Name&lt;/template&gt;
                  &lt;template&gt;[[item.lastName]]&lt;/template&gt;
              &lt;/vaadin-grid-column&gt;
  
          &lt;/vaadin-grid&gt;
      &lt;/template&gt;
  
      &lt;script&gt;
          /**
           * @customElement
           * @polymer
           */
          class ScheduleVaadinTest extends Polymer.Element {
              static get is() {
                  return 'schedule-vaadin-test';
              }
  
              static get properties() {
                  return {
                      items: {
                          type: Array,
                          value: [{"firstName":"Foo", "lastName":"Bar"},
                                  {"firstName":"Foo", "lastName":"Bar"},
                                  {"firstName":"Foo", "lastName":"Bar"}]
                      },
  
                      selectedItems: {
                          type: Array,
                          observer: 'selectedItemsChanged'
                      }
                  };
              }
  
              static get observers() {
                  return []
              }
  
              selectedItemsChanged() {
                  console.log(this.selectedItems);
              }
          }
  
          customElements.define(ScheduleVaadinTest.is, ScheduleVaadinTest);
      &lt;/script&gt;
  &lt;/dom-module&gt;
  </code></pre>