title: how to automatically get date in specific format from DatePicker?
body: <p>I'm using the component <code>DatePicker</code> from antd.</p>
  <p>I have currently a <code>Form</code> from antd, in which there's a <code>Form.Item</code>, in which I put the <code>DatePicker</code>.</p>
  <p>I want the <code>Form.Item</code> to be given the date in a specific format, lets say <code>YYYY-MM-DD</code>, is there a way to do that?</p>
  <p>by giving it the prop <code>format</code> I can choose how it will look like in the UI but I'm trying to make it send back the value by the same format.</p>
  <p>I've tried giving it a <code>dateFormat</code> prop with the function</p>
  <pre><code>function dateFormat(date) {
    return moment(date).format(&quot;YYYY/MM/DD&quot;);
  }
  </code></pre>
  <p>but it doesn't work.</p>
  <p>is there a way to do this manipulating the data in the onChange function?</p>