Yup validation transforms date string to datetime

Version Number

Codesandbox/Expo snack

https://codesandbox.io/s/react-hook-form-v7-yup-and-dates-p80hu

Steps to reproduce

Hello, First of all thanks for this wonderful library and the new V7. I have been experiencing an unexpected behavior when using react-hook-form with yup for date validation. This also happens when using v6 I believe.

Go to sandbox
Choose a date
Click submit and check console
Date field value in watch is a string of type yyyy-mm-dd
However data from on submit is of type Date (basically a timestamp)

Expected behaviour

I would expect form data not not to be transformed by yup resolver, meaning formState = data passed in on submit. I assume what’s happening is that Yup parse the date string into a Date Object and that is the element returned

What browsers are you seeing the problem on?

No response

Relevant log output

submited data =  Thu Feb 03 2022 00:00:00 GMT+0100 (heure normale d’Europe centrale)
form Data =  2022-02-03

Code of Conduct

I agree to follow this project’s Code of Conduct

Issue Analytics

State:
Created 2 years ago
Comments:15 (13 by maintainers)

Top GitHub Comments

4reactions

Moshyfawncommented, Feb 3, 2022

I wouldn’t consider making a change at the moment

What change are we talking about? Yup transforms the values to “help with validation” which is very subjective and totally different from, say, Zod’s paradigm, where they sure allow you to preprocess the value before validating, but they don’t mutate the actual value. It’s not like it’s RHF job to bring everyone “up to standard”, as it all depends on the validation lib ppl choose for the way they handle the data (transform the data or not in case of Yup and Zod). If RHF takes the responsibility to update (or not) the validated data, there gonna be tons of ppl with different libs creating issues on how the behavior of RHF doesn’t match their lib.

To sum it up, IMO, if you use Yup, you can expect the values to be “mutated” during the validation, as Yup does exactly that. If you use, say, Zod, it’s their paradigm that you chose and don’t expect the values to be mutated during the validation

2reactions

chrisbagcommented, Feb 3, 2022

Thanks for your views that I completely understand and it makes senses. I hope this will help out some react-hook-form/ yup users stumbling into the same issue. I was surprised that one would potentially expect the validation library to mutate data. I’ll probably just make my custom resolver to solve this issue 😁 thanks for your time