[Bug v7.0.0] useField returns undefined value on initial render despite initialValues being set

[yurii-oliiarnyk-finsight]

Description

Hi, thanks for your work on the library!

We're encountering a blocking issue when trying to migrate to react-final-form@7.0.0 to prepare for React 19.

Problem

When initialValues are passed to the <Form />, the corresponding fields registered via useField initially return value: undefined. This was not the case in earlier versions.

It seems that the field state is now derived via form.getFieldState() during initialization here — but this runs before the field is registered here, so the field state is not available at that moment.

As a result:

Fields render with value: undefined on the first render. Components relying on the initial value (e.g., to initialize local state or trigger effects) fail or misbehave.

Expect result:

Fields render with defined value on initialize as it was before in v6.5.9

Sandbox Link

v6.5.9 https://codesandbox.io/p/sandbox/h7lk86
Logs:

v7.0.0 https://codesandbox.io/p/sandbox/6cd2fz
Logs:

[chevvy]

Noticed the same issue while migrating to expo 53/React 19. At first, I assumed there was something wrong with our ref usage and React 19 changes, but in the end I figured final-form might be at cause.
In the end:

• We kept the changes to expo53/react 19
• Reverted to final-form:4.20.10 and react-final-form:6.5.9
• Overrides were set for both package to use React-19
  And everything seems to work fine. So there seems to be something that changed with the changes in 7.0.0, but haven't had the time to look at the code yet.