Error message based on input value

[Jack-Works]

I need to generate error message based on the input value, now I have to use errorMap which is tedious.

I hope I can write code like this:

z
.string({ invalid_type_error: value => 'Expected a string, received: ' + String(value) })
.min(2, { message: value => 'Expected a string with at least 2 characters, received: ' + String(value) })

[JacobWeisenburger]

Is this what you are looking for?

const schema = z.string( {
    errorMap: ( issue, ctx ) => {
        switch ( issue.code ) {
            case 'invalid_type': return {
                message: `Expected a string, received: ${ ctx.data }`
            }
            case 'too_small': return {
                message: `Expected a string with at least ${ issue.minimum } characters, received: ${ ctx.data }`
            }
            default: return {
                message: ctx.defaultError
            }
        }
    }
} ).min( 2 )

const result1 = schema.safeParse( 42 )
!result1.success && console.log( result1.error.issues )
// [
//     {
//       code: "invalid_type",
//       expected: "string",
//       received: "number",
//       path: [],
//       message: "Expected a string, received: 42"
//     }
// ]

const result2 = schema.safeParse( 'a' )
!result2.success && console.log( result2.error.issues )
// [
//     {
//       code: "too_small",
//       minimum: 2,
//       type: "string",
//       inclusive: true,
//       exact: false,
//       message: "Expected a string with at least 2 characters, received: a",
//       path: []
//     }
// ]

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[Jack-Works]

Is this what you are looking for?

This is possible, but annoying to write. I just want to write those error inline.

[Aniket1026]

I need to generate error message based on the input value, now I have to use errorMap which is tedious.

I hope I can write code like this:

z
.string({ invalid_type_error: value => 'Expected a string, received: ' + String(value) })
.min(2, { message: value => 'Expected a string with at least 2 characters, received: ' + String(value) })

I Agree with you as I'm also looking for exactly the same thing as having your own custom errors is super helpful. I hope they do this soon but have you found any better approach or way of doing the same thing which you've requested?

[joaoGabriel55]

I can work on that! @JacobWeisenburger

[colinhacks]

I think something like this should definitely happen, but it won't look exactly like this. This will land in Zod 4. More details here https://github.com/colinhacks/zod/pull/3152#issuecomment-1945200427 Leaving open for now.

[LorisSigrist]

This would also be quite valuable for i18n use-cases, since the language of the error-message usually needs to be determined the moment parsing happens instead of upfront when the module loads.