feat(form-core): Validation on first and consequent attempts

[theVedanta]

Enables functionality like:

const form = useForm({
  defaultValues: {
    firstName: '',
    lastName: '',
  },
  validators: {
    onBlur: ({ value }) => {
      console.log('ON Blur:', value)
    },
    onMount: ({ value }) => {
      console.log('ON Mount:', value)
    },
  },
  validationOnFirstAttempt: 'blur',
  validationOnConsequentAttempts: 'mount',
})

This is in reference with issue #1272
All kinds of criticism, API-related edits, structural edits, etc. are welcome!

The current approach is quite verbose and adds an option in the formOptions that could be attributed to an object. However, since I don't know what we can attribute it to, keeping this style of options open.

Let me know if the functionality seems ok and we can work on documentation/writing tests.

[nx-cloud]

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---

☁️ Nx Cloud last updated this comment at 2025-03-15 19:03:46 UTC

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commit: 9559bc1

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All modified and coverable lines are covered by tests ✅

Project coverage is 88.83%. Comparing base (b0dc32c) to head (9559bc1).
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@@            Coverage Diff             @@
##             main    #1286      +/-   ##
==========================================
+ Coverage   88.32%   88.83%   +0.51%     
==========================================
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  Lines        1199     1272      +73     
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==========================================
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[Balastrong]

Thanks for the PR!

However I'm not entirely sure this is the right direction. I see it quite confusing to define a submit validator and then a flag to have a different validator... only if it's the first attempt.

The current approach is quite verbose

What approach are we covering with this new api?

[theVedanta]

Thanks for the PR!

However I'm not entirely sure this is the right direction. I see it quite confusing to define a submit validator and then a flag to have a different validator... only if it's the first attempt.

The current approach is quite verbose

What approach are we covering with this new api?

That's totally fair. I honestly think that checking submission attempts and defining a behaviour for validation would be quite verbose and this proves to be an alternative. React Hook Form has a similar API as mentioned in the issue referenced.

However, if you think that this kind of an option is not required in the tanstack-form, that would be understandable.

[da1z]

for me something like validationType and revalidationType sound more intuitive

[theVedanta]

Alright I'll seek some approval about this and let you know!

[Balastrong]

I'd probably not move forward with this. I see value in adding those flags, but:

• the same behaviour can be implemented in user-land with a single if
• they're too specific on a single use case
• if we allow for that, then we should add so many other flags and logic for everyone's individual needs which means paying a lot in maintenance on the long run

Thanks anyway, if we see more demand in the future we might think of a different API to handle that :)