Breaking change between 7.22.4 & 7.22.5

[o-alexandrov]

Version Number

7.22.5

Codesandbox/Expo snack

https://codesandbox.io/s/sharp-margulis-wf7myr

Steps to reproduce

1. Go to provided Codesandbox
2. Use version 7.22.5
3. Open console
4. Click on Set name to undefined
5. Observe the bug: FieldController doesn't get an value update (no console)

Go back to step 2, use version 7.22.4, repeat steps, and see that it correctly updates the value to undefined and triggers an update (console statement is invoked)

Expected behaviour

• setValue to undefined triggers an update and does update the value to undefined (currently it doesn't)

What browsers are you seeing the problem on?

No response

Relevant log output

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[bluebill1049]

Thanks for the issue report, however, please refer to the doc undefined value is not supported. The patch is most likely due to a bug fix, and you can consider using another type of default value instead.

[o-alexandrov]

@bluebill1049 how do you suggest to remove a value from form values?

[o-alexandrov]

Btw, the breaking change was introduced in this set of changes and in this file

[o-alexandrov]

I hope you do reconsider, as suggesting users-developers to patch on their side for conversion (ex. undefined => null) is error-prone for users whereas it should be handled by the library.

[bluebill1049]

If an input is removed or unmounted, then it should use unregister function.

[o-alexandrov]

The input exists, the value is removed from a form.
Based on your message and the logic behind removal of a feature to setValue(fieldName, undefined), I guess you believe a user-developer should:

• unregister
• and register again

context.unregister(name)
context.register(name)

Do you really think this is a good DX for a developer to remove a value from a form?

[o-alexandrov]

The really bad part here is:

• setValue doesn't complain in the provided code sandbox that undefined is not allowed

So many other devs would stumble on this error

[bluebill1049]

setValue doesn't complain in the provided code sandbox that undefined is not allowed

It's a valid point above, I will tighten up the type. Everything else will stay the same.

[o-alexandrov]

So there will be no way to remove a value.
No alternative to previous:
setValue(fieldName, undefined)

I hope you will reconsider, as many developers looking at this issue would probably lose trust in this library to be safe long-term, especially with breaking changes in patch versions.

[o-alexandrov]

setValue doesn't complain in the provided code sandbox that undefined is not allowed

It's a valid point above, I will tighten up the type. Everything else will stay the same.

Even if you change typings, it won’t help devs in all cases, as event’s target in inputs is typed in a way that it’s always truthy.

• as well as it’s naive to think deeply nested fields using useFormContext would be all correctly typed on a possible undefined value

The only safe way to handle this is to actually handle undefined within the library, not to depend on a developer to know about this nuance.