title: How to get children values on antd's form submit?
body: <p>I made a custom component called <code>TagsInput</code>, and added it to a form. My problem is, when the form is submitted, the value for field <code>tags</code> is always undefined, because the <code>Form.Item</code> cannot retrieve the value from the <code>TagsInput</code> child. This is usually not a problem when children of <code>Form.Item</code> are antd components.</p>
  <pre><code>export default function NewProjectForm(props) {
    return (
      &lt;Form layout=&quot;vertical&quot; onFinish={props.onSubmit} id=&quot;newProjectForm&quot;&gt;   
        &lt;Form.Item label=&quot;Tags&quot; name=&quot;tags&quot;&gt;
          &lt;TagsInput /&gt;
        &lt;/Form.Item&gt;
      &lt;/Form&gt;
    );
  }
  </code></pre>
  <p><code>TagsInput</code> is a class component that has its value within its state:</p>
  <pre><code>class TagsInput extends React.Component{
      constructor(props){
          super(props);
          this.state = {
              value: []
          }
      }
  
      render(){
          return(&lt;div&gt;&lt;/div&gt;)
      }
  }
  </code></pre>
  <p>I dont want to elevate the value field from <code>TagsInput</code> state to <code>NewProjectForm</code> because it is not a class component... I would be doing it just for the sake of solving this issue. I am asking this question because I think there is a cleaner way of solving this.</p>
  <p>How can I make <code>NewProjectForm</code> retrieve the value of <code>TagsInput</code> from within its state?
  Is there any function I can pass to <code>TagsInput</code> as a property, so that the form asks the component for a value when it is submitted?</p>