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Adds example for optional #1321

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Adds example for optional #1321

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5cd4e7e
Add example for optional defaulting to undefined
robations Sep 25, 2025
81a2ea1
Fix editing typo
robations Sep 25, 2025
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12 changes: 12 additions & 0 deletions website/src/routes/api/(schemas)/optional/index.mdx
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Expand Up @@ -80,6 +80,18 @@ const OptionalNumberSchema = v.optional(v.number());
const NumberSchema = v.unwrap(OptionalNumberSchema);
```

### Default to `undefined`

If you wish optional entries to default to an `undefined` value, you must pass the `default_` parameter as a function returning `undefined`, otherwise this will be seen as no parameter being passed.
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Should we change it to "If you wish missing object entries to default to an undefined value, ..."?


```ts
const OptionalEntrySchema = v.object({
key: v.optional(v.string(), () => undefined),
});
const res = v.parse(OptionalEntrySchema, {});
// res = { key: undefined };
```
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I think I would just write this to be consistent with the other example. But I see why you added it.

const OptionalEntrySchema = v.object({
  key: v.optional(v.string(), () => undefined),
});


## Related

The following APIs can be combined with `optional`.
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