title: Actions with validation
body: <p>It's good that react admin provide actions for us to use in edit/create page. However, the simple form is the child component so the action is without control to the simple form. If I want to validate form data before using fetch to send to the server, how do I trigger the validation?
  <a href="https://github.com/marmelab/react-admin/blob/master/docs/Actions.md" rel="nofollow noreferrer">https://github.com/marmelab/react-admin/blob/master/docs/Actions.md</a></p>
  
  <p>Thanks!</p>