Field-level validation not working when using `useField` hook

🐛 Bug report

Current Behavior

When using the useField hook, field-level validation using the validate property doesn’t work.

const [field] = useField({ name, validate: () => 'not good' });

Expected behavior

The validate prop should work just like its Field counterpart.

Reproducible example

https://codesandbox.io/embed/formik-codesandbox-template-p5zc1

Suggested solution(s)

Manually registering the validate function does the trick for me:

useEffect(() => {
  registerField(name, {
    validate: () => 'not good'
  });

  return () => unregisterField(name);
}, [name, registerField, unregisterField]);

Your environment

Software	Version(s)
Formik	2.0.1-rc.9
React	16.8.6
TypeScript	3.5.2
Browser	Chrome 75
npm/Yarn	npm
Operating System	Ubuntu 19.04

[mordechaim]

Why is this behavior not documented here?

I ran into this page by searching how to do field-level validation using hooks.

[johnrom]

@mordechaim you’re free to open a PR to update the documentation