title: How to get an input field value in Vue
body: <p>I'm new to Vue and I would like some help getting a value from an input field:</p>
  <p>In my form I have:</p>
  <pre class="lang-html prettyprint-override"><code>&lt;input type=&quot;hidden&quot; id=&quot;groupId&quot; value=&quot;1&quot;&gt;
  </code></pre>
  <p>If I was using jQuery I would do:</p>
  <pre class="lang-js prettyprint-override"><code>var group_id = $('#groupId').val();
  </code></pre>
  <p>However, in Vue I don't know how to bind the hidden field:</p>
  <pre class="lang-html prettyprint-override"><code>&lt;div id=&quot;app&quot;&gt;
     &lt;input type=&quot;text&quot; v-model=&quot;groupId&quot;&gt; //Where do I put the value?
  &lt;/div&gt;
  </code></pre>
  <pre class="lang-js prettyprint-override"><code>new Vue({
      el: '#app',
      data: {
          groupId: //What do I put here to get the field's value?
      }
  </code></pre>
  <p>How can I achieve this?</p>