title: how to use ant design form initialValue
body: <p>Which is right using antd Form initialValue?</p>
  
  <p>I want to know that if antd form initialValue is using to set initial data or just to show value when the form doesn't have value.</p>
  
  <pre><code>const Component = ({ id }) =&gt; {
    const initialName = 'John'
    const { data } = useQuery(GET_NAME, { variables: { id } })
    if (data) { 
      initialName = data.name 
    }
  
    return (
    &lt;Form.Item&gt;
      {form.getFieldDecorator('name', { initialValue: initialName })(&lt;Input /&gt;)}
     &lt;/Form.Item&gt;
   )
  }
  
  </code></pre>
  
  <pre><code>const Component = ({ id }) =&gt; {
    const { data } = useQuery(GET_NAME, {
      variables: { id },
      onCompleted: res =&gt; { form.setFieldsValue({ name: res.data.name }) }
    })
  
    return (
    &lt;Form.Item&gt;
      {form.getFieldDecorator('name', { initialValue: 'John' })(&lt;Input /&gt;)}
     &lt;/Form.Item&gt;
   )
  }
  </code></pre>