title: How to select all options in multiselect Kendo UI dropdown?
body: <p>There is a MultiSelect DropDown from kendo ui mvc, I would like to have a select all option that when you click on that, all the options will be selected.
  Here's my code:</p>
  <pre><code>@(Html.Kendo().MultiSelect()
          .HeaderTemplate(&quot;&lt;label&gt;&lt;input type=\&quot;checkbox\&quot; id=\&quot;selectAll\&quot;&gt; select all &lt;/label&gt;&quot;)
          .Name(&quot;schoolNames&quot;)
          .Filter(&quot;Contains&quot;)
          .HtmlAttributes(new {style = &quot;width: 100%;&quot;})
          .DataTextField(&quot;title&quot;)
          .DataValueField(&quot;id&quot;)
          .AutoClose(false)
          .Events(e =&gt; e.Change(&quot;selectAllChange&quot;))
          .DataSource(source =&gt;
          {
              source.Read(read =&gt;
              {
                  read.Url( &quot;/api/v1/Moodle/names/&quot;);
              })
                  .ServerFiltering(false);
          })
          )
  </code></pre>