issue: input doesn't pick up value after remount

[lukasgebhard]

Version Number

7.45.2

Codesandbox/Expo snack

https://codesandbox.io/s/frosty-bose-wn2fqh

Steps to reproduce

1. Empty formField1.
2. Enter "1" into formField1.

Expected behaviour

formField2 displays "2".

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

[lukasgebhard]

Note that the data the form submits (after following the above steps) depends on the used version of react-hook-form:

• v7.38.0: {formField1: "1", formField2: undefined}
• v7.45.2: {formField1: "1", formField2: "2"}

In both cases, formField2 doesn't display any value, though.

[lukasgebhard]

Related issues:

• issue: watch the field in Controller with defaultValues and shouldUnregister: true return undefined #10096
• issue: Watch, shouldRegister true and StrictMode #10700
• issue: Controlled input doesn't register when conditionally mounted #10386
• issue: Controller with shouldUnregister=true is loosing its value in StrictMode #8669

[bluebill1049]

shouldUnregister with strict mode is troublesome, i recommend invoking unreigster manually at your own app level.

[lukasgebhard]

Hi @bluebill1049,

Thank you for the fast reply and all your work to maintain this project!

shouldUnregister with strict mode is troublesome, i recommend invoking unreigster manually at your own app level.

As you can see in the provided code sandbox, the reported issue occurs without strict mode.

[bluebill1049]

it is shouldUnregister={true}, your component gets unmounted and after unmount. The data is destroyed. If you want to fine-tune the experience, I would recommend to manually invoke unregister api.

[lukasgebhard]

I would recommend to manually invoke unregister api.

In the given code sandbox example, how would that help to restore formField2's default value?

[lukasgebhard]

Now I've found a way:

1. Remove shouldUnregister={true}
2. Call unregister('formField2', {"keepDefaultValue": true})

Here the full workaround: https://codesandbox.io/s/rhf-issue-workaround-qqmrj8

[lukasgebhard]

after unmount. The data is destroyed.

But why does the form submit the default value then? See my previous comment

In my view, it's clearly a bug that after re-mounting formField2, its default value is present but not rendered. Either the default value should be gone entirely, or it should be present and rendered properly.

[sKopheK]

i've recently bumped into few cases when unregistering field removes its default value (it's actually in the library code itself, not any side effect). when it's displayed and registered again, there's no value whatsover. why would the library remove anything from defaultValues? i'd like to prevent any fidling with such "constant" object using Object.freeze, but it'd cause error