React hook form - Register field not working

Question

here is my codesandbox, I'm manually registering two fields, if I click submit w/o entering any data I see required field validation, which works fine and if I unregister "lastname" it removes error from last name, however,

The problem: first name still shows required validation even if I enter data. I tried removing manual registering a field and it work fine. But that is not my requirement. Any help. Thank you.

Answer 1

setValue doesn't trigger validation by default:

https://react-hook-form.com/api#setValue

- onChange={(e) => setValue("firstName", e.target.value)}
+ onChange={(e) => setValue("firstName", e.target.value, { shouldValidate: true } )}

Answer 2

Based on documentation you need to use "ref" in order to register needed field. Read here:

https://react-hook-form.com/api#register

I also updated your example:

https://codesandbox.io/s/react-hook-form-unregister-v6-forked-6wq09?file=/src/index.js

Have fun!