.nullable and .default

[mariusmarais]

EDIT: I see in #421 (comment) it's not actually supposed to work this way... In which case I request that a "default() for nulls" or "default() handles nulls" be added, since I cannot figure out a way to do this without removing the null before passing to zod.

(Using 3.0.0-beta.1)

I expect .nullable().default(...) to not have xxx | null in the output type, in the same way that (redundancy aside) .optional().default(...) does not have xxx | undefined, but I'm not 100% sure my reasoning is correct.

Should .default() replace null values, so that number().nullable().default(1) => number or number | null?
Or does .default() only operate on undefineds?

Should the chaining order matter so that number().nullable().default(1) => number and number().default(1).nullable() => number | null?

Example:

// Given
export const PaginationInputSpec = z
  .object({
    page: z.number().default(1),
    perPage: z.number().default(100)
  })
  .nullable()
  .default({});

// I expect:
PaginationInputSpec.parse(undefined) => { page: number, perPage: number }
// AND
PaginationInputSpec.parse(null) => { page: number, perPage: number }

// but I get 
PaginationInputSpec.parse(...) => { page: number, perPage: number } | null

Is this a bug?

I can try to work around it with:

...
  .nullable()
  .transform((i) => i ?? undefined)
  .default({});

which removes the | null from the output type, but it DOESN'T ACTUALLY WORK AT RUNTIME, making the whole thing undefined. I expected the "inner" defaults to then take effect, but they don't.

Using in a GraphQL API where input optionals can be entirely missing (undefined) or explicitly null.

[colinhacks]

Like you said there's no way to do this right now. I think I'm going to introduce a "preprocess" method that would let you attach logic like this to your schema prior to parsing, something like this:

const PaginationInputSpec = z
  .object({
    page: z.number().default(1),
    perPage: z.number().default(100),
  })
  .preprocess((val: unknown) => {
    return val ?? {};
  })

But for now the best way is to duplicatively define your defaults:

const PaginationInputSpec = z
    .object({
      page: z.number().default(1),
      perPage: z.number().default(100),
    })
    .nullable()
    .default({})
    .transform((val) => {
      return val ?? { page: 1, perPage: 100 };
    });

[mariusmarais]

Yes, ended up doing exactly that 😄

[stale]

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