Is there a simple way to get only the altered form field values?

[ericvanular]

In react-hook-form, one can use formState.dirtyFields to obtain all of the form fields that have been changed. Ideally I wouldn't be sending the entire form state to my backend when only one field has been changed. But it feels complicated to figure this out upon form submission. What is the recommended way to do this?

[LeCarbonator]

It's not provided by the library as of v1.11.3, I'm afraid. Meta properties like isDefaultValue work on field and form level, but to actually extract the modified ones is a different story.

If that's all you need, then you can iterate over formApi.fieldMetaDerived.state, which gives you a record of each field meta. Filter out any where isDefaultValue === true

However, obtaining the diffs between two objects in JavaScript is a big topic, and you have both access to the current values value as well as the defaultValues formApi.options.defaultValues. There should be small libraries available to extract the differences.

[ericvanular]

Thanks for the informed response @LeCarbonator.

This is an extremely common functionality that many people would need. Perhaps it should be in the project roadmap if it isn't already? For now, since "dirtyFields" are provided out of the box by react-hook-form, implementing the same thing from scratch here adds needless complexity and prevents me from switching to Tanstack Form. I appreciate the work that the team is doing on this project and understand that it is early days still so things like this may not be covered yet