superRefine breaks compatibility with discriminatedUnion

[cdaringe]

Problem

Here's an easy demo, using [email protected]

import * as z from "zod";

const schemaA = z.object({
  version: z.literal("a"),
}); // observation, no use of superRefine

z.discriminatedUnion("version", [schemaA]); // works

const schemaB = z
  .object({
    version: z.literal("b"),
  })
  .superRefine(() => {}); // observation, use of superRefine

z.discriminatedUnion("version", [schemaB]); // doesn't work

/*
Type 'ZodEffects<ZodObject<{ version: ZodLiteral<"b">; }, "strip", ZodTypeAny, { version: "b"; }, { version: "b"; }>, { version: "b"; }, { version: "b"; }>' is missing the following properties from type 'ZodObject<{ version: ZodTypeAny; } & ZodRawShape, UnknownKeysParam, ZodTypeAny, { [x: string]: any; version?: any; }, { [x: string]: any; version?: any; }>': _cached, _getCached, shape, strict, and 14 more.ts(2740)
*/

The type-error is correct, and it breaks at runtime as well.

In otherwords, ZodEffect<ZodObject> isn't supported... but it should be! A schema that has assertions on top of it is still a compatible schema.

Expectation

z.discriminatedUnion to still work on .superRefined schemas.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[cdaringe]

ah jamon. have had a patch open for this issue for months

[jonavila]

Just hit this bug. Any workaround?

[cdaringe]

None. I submitted a patch, but it has idled. I ended up just using .union

On Fri, Sep 22, 2023 at 7:26 AM Jonathan Avila @.***> wrote:

Just hit this bug. Any workaround?

— Reply to this email directly, view it on GitHub https://github.com/colinhacks/zod/issues/2440#issuecomment-1731517695, or unsubscribe https://github.com/notifications/unsubscribe-auth/AAHU57OLSAKLULUDI7VMMMDX3WNZXANCNFSM6AAAAAAYFOZBP4 . You are receiving this because you authored the thread.Message ID: @.***>

[johnslemmer]

I have ran in to this as well. I was about to submit my own issue with this example: https://codesandbox.io/p/sandbox/suspicious-bash-4z8ptf but found this issue instead.

[colinhacks]

This will be fixed in Zod 4 per https://github.com/colinhacks/zod/pull/2441#issuecomment-2044094604

Leaving open until then.

[premdasvm]

I've ran into the same issue, is there a work around?

const SubPartQuestionZodSchema = QuestionSchema.extend({
	Type: z.literal(QuestionTypes.SUB_PART),
	Questions: z.array(z.lazy(() => QuestionZodSchema)),
});

export const QuestionZodSchema = z.discriminatedUnion("Type", [
	FillInTheBlankQuestionZodSchema,
	EssayQuestionZodSchema,
	SubPartQuestionZodSchema,
]);

wanted to add a superRefine to SubPartQuestionZodSchema

const SubPartQuestionZodSchema = QuestionSchema.extend({
	Type: z.literal(QuestionTypes.SUB_PART),
	Questions: z.array(z.lazy(() => QuestionZodSchema)),
}).superRefine((data, ctx) => {
	if (data.QuestionLevel !== QuestionLevel.SUBJECT) {
		if (!data.Metadata.Subjects || data.Metadata.Subjects.length <= 0) {
			ctx.addIssue({
				code: z.ZodIssueCode.invalid_type,
				expected: "array",
				received: typeof data.Metadata.Subjects,
				message: "Subjects can't be empty",
			});
		}
	}
});

[sloonz]

The workaround is to build the ZodDiscriminatedUnion manually :

function zDiscriminatedUnion<T extends readonly [z.ZodTypeAny, z.ZodTypeAny, ...z.ZodTypeAny[]]>(key: string, types: T): z.ZodUnion<T>;
function zDiscriminatedUnion(key: string, types: z.ZodTypeAny[]): any {
  const optionsMap = new Map();
  for(const type of types) {
    const value = (type instanceof z.ZodEffects ? type.sourceType() : type).shape[key];
    if(!(value instanceof z.ZodLiteral) || optionsMap.has(value.value)) {
      throw new Error("cannot contruct discriminated union");
    }
    optionsMap.set(value.value, type);
  }
  return new z.ZodDiscriminatedUnion({typeName: z.ZodFirstPartyTypeKind.ZodDiscriminatedUnion, discriminator: key, options: types as any, optionsMap});
}