discriminated union with dataType json causing SchemaError

[konstantinblaesi]

Error trace

SchemaError: [addresses.additional.name] No default value specified for field (can be undefined, but must be explicit)
    at Defaults_traverseAndReplace (/projects/sveltekit-superforms/src/lib/errors.ts:290:11)
    at Errors_traverseAndReplace (/projects/sveltekit-superforms/src/lib/errors.ts:237:4)
    at Data_traverse (/projects/sveltekit-superforms/src/lib/errors.ts:221:3)
    at Module.replaceInvalidDefaults (/projects/sveltekit-superforms/src/lib/errors.ts:303:10)
    at Module.superValidate (/projects/sveltekit-superforms/src/lib/superValidate.ts:139:5)
    at /projects/sveltekit-superforms/src/tests/demo.test.ts:55:13
    at runTest (file:///projects/sveltekit-superforms/node_modules/.pnpm/@[email protected]/node_modules/@vitest/runner/dist/index.js:781:11)
    at runSuite (file:///projects/sveltekit-superforms/node_modules/.pnpm/@[email protected]/node_modules/@vitest/runner/dist/index.js:909:15)
    at runSuite (file:///projects/sveltekit-superforms/node_modules/.pnpm/@[email protected]/node_modules/@vitest/runner/dist/index.js:909:15)
    at runFiles (file:///projects/sveltekit-superforms/node_modules/.pnpm/@[email protected]/node_modules/@vitest/runner/dist/index.js:958:5) {
  path: 'addresses.additional.name'
}

From the repro: The testcase bad produces this error trace, testcase good works
Basically the feature is to provide one of three possible address types, something like

addresses.additional.type = { 'type1', 'type2', 'none' }

where the 'none' type has no additional fields

Repro

Code

import { zod } from "$lib/adapters/zod.js";
import { superValidate } from "$lib/superValidate.js";
import { stringify } from "devalue";
import { describe, test } from 'vitest';
import { z } from "zod";

const ZodSchema = z.object({
    addresses: z.object({
        additional: z.discriminatedUnion('type', [
            z.object({
                type: z.literal('poBox'),
                name: z.string()
                    // these constraints cause the test failure
                    // Validation error instead of schema error would be expected?
                    .min(1, "min len").max(10, "max len")
                    .default("")
            }),
            z.object({
                type: z.literal('none'),
            }),
        ])
    })
})
const FormSchema = zod(ZodSchema)
type FormSchema = typeof FormSchema['defaults']

async function validate(data: unknown) {
    const formInput = new FormData()

    formInput.set('__superform_json', stringify(data));
    try {
        await superValidate(formInput, FormSchema)
    } catch (err) {
        console.error(err)
        //
        throw err
    }
}

describe("Demo", () => {
    test("Bad", async () => {
        const data = {
            addresses: {
                additional: {
                    type: 'poBox',
                    name: ''
                }
            }
        } satisfies FormSchema;
        await validate(data)
    })

    test("Good", async () => {
        const data = {
            addresses: {
                additional: {
                    type: 'none'
                }
            }
        } satisfies FormSchema;
        await validate(data)
    })
})

Should this kind of schema work ? Should this be modeled differently?

[ciscoheat]

You can't stringify __superform_json directly, you need to use devalue. Try that and see if it works. Otherwise you should try to add a default value to the schema, as suggested by the error.

[konstantinblaesi]

I updated the code. The field addresses.additional.name is a required field and I would expect a validation error when empty string is submitted, but instead I get a schema error / crash from superforms ? Where would the default value be placed to fix the issue ? So far I have not had success with default values

[konstantinblaesi]

This schema

const ZodSchema = z.object({
    addresses: z.object({
        additional: z.discriminatedUnion('type', [
            z.object({
                type: z.literal('poBox'),
                name: z.string()
                    // these constraints cause the test failure
                    // Validation error instead of schema error would be expected?
                    .min(1, "min len").max(10, "max len")
                // .default("")
            }),
            z.object({
                type: z.literal('none'),
            }),
        ])
            .default({ type: 'none', name: '123' })
    })
})

fixes the error and produces this result from superValidate

RESULT {
  id: '1s92os',
  valid: false,
  posted: true,
  errors: {
    addresses: { additional: { name: [ 'min len' ] } }
  },
  data: { addresses: { additional: { type: 'poBox', name: '' } } }
}

but if this is the fix , it is not intuitive since it screems at me in my IDE :D

[ciscoheat]

There was a problem with the recursive check for discriminated unions, will be fixed in the next release. No default will be required.

[konstantinblaesi]

Thanks for the fix! Sadly when assigning a default value on a nested discriminated union things break. Is this expected or should this work?

[ciscoheat]

Fixed now with 2.21.1