How to customize the error message of z.coerce.date()?

[tordans]

When I use z.date() I can customize the error message like …

z.date({
  required_error: "Date is required.",
  invalid_type_error: "Wrong date format.",
}),

However, once I use z.coerce.date() the error messages are ignored (or "not reached").

For example, z.coerce.date().parse('') returns…

Uncaught ZodError: [
  {
    "code": "invalid_date",
    "path": [],
    "message": "Invalid date"
  }
]

I assume that ZodError gets this message from new Date(''), which also return Invalid date.

However, since I use react-hook-form with a zod schema, I "have to" provide the error messages via zod (or start doing some hacky workarounds).

As far as I see, right now there is no way to change this behavior (eg. coerce does not accept an error message).

Is this considered a Bug or a feature in Zod? And how would you recommend working around it?

---

A few thoughts on how to improve the DX:

• the error message from .date could overwrite that by .coerce
• .coerce could get an optional message to be used
• if possible TS could mark required_error and invalid_type_error as never whenever .date is chained on top of .coerce, since those message will never work
• the docs could hint at this special behavior

[JacobWeisenburger]

Is this what you are looking for?

const schema = z.coerce.date( {
    errorMap: ( { code }, { defaultError } ) => {
        if ( code == 'invalid_date' ) return { message: 'Wrong date format.' }
        return { message: defaultError }
    }
} )

const result = schema.safeParse( '' )
!result.success && console.log( result.error.issues[ 0 ] )
// { code: 'invalid_date', path: [], message: 'Wrong date format.' }

[tordans]

@JacobWeisenburger thanks a lot, that is exactly what I needed. Would a PR be welcome to hint at this in the coerse section?

[JacobWeisenburger]

PRs are always welcome. Let me know when it's ready and I'll review it.

[lsa-jose-israel]

Shouldnt the message be overriden if you pass it in the { message } parameter? Do you need to define a whole custom map for every date field?