Leverage Zod's discriminated union feature by using an enum discriminator without the need to explicitly list out all

Question

Leverage Zod's discriminated union feature by using an enum discriminator without the need to explicitly list out all

I am currently attempting to utilize Zod schema validation for data with varying constraints depending on the value of an enumeration field (generated by Prisma). The data can take the following formats:

{ discriminatorField: "VAL1", otherField: "any string" }

{ discriminatorField: "any other allowed string besides VAL1", otherField: undefined }

It appears that this can be achieved using z.discriminatedUnion() as shown below:

const schema = z.discriminatedUnion("discriminatorField", [
   z.object({ discriminatorField: z.literal("VAL1"), otherField: z.string()}),
   z.object({ discriminatorField: z.literal("VAL2"), otherField: z.string().optional()}),
   // ... must list all possible enum values as literal conditions here?
])

While this method works, it requires listing out all potential enum values for discrimination. I attempted using z.nativeEnum(MyEnum) instead of z.literal("VAL2") in the code above, but Zod raised an error about overlapping values. Although technically correct, I had hoped it would prioritize the first matching case.

typescript validation enums discriminated-union zod

Answer 1

Answer №1

Here is a code snippet that defines a discriminated union schema in JavaScript using the zod library:

const schema = z.discriminatedUnion("discriminatorField", [
  z.object({ discriminatorField: z.literal("VAL1"), otherField: z.string() }),
  ...Object.values(MyEnum)
    .filter((enum) => enum !== "VAL1")
    .map((enum) =>
      z.object({
        discriminatorField: z.literal(enum),
        otherField: z.string().optional(),
      }),
    ),
]);

Answer 2

Here is a code snippet that defines a discriminated union schema in JavaScript using the zod library:

const schema = z.discriminatedUnion("discriminatorField", [
  z.object({ discriminatorField: z.literal("VAL1"), otherField: z.string() }),
  ...Object.values(MyEnum)
    .filter((enum) => enum !== "VAL1")
    .map((enum) =>
      z.object({
        discriminatorField: z.literal(enum),
        otherField: z.string().optional(),
      }),
    ),
]);

Leverage Zod's discriminated union feature by using an enum discriminator without the need to explicitly list out all

Answer №1

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