Beta 5 fixes partial and deepPartial making it work correctly with lazy schema. Specifically the optionality is added after lazy is evaluated but before any other when conditions are added. This makes it consistent with other conditional schema, where runtime conditions always supersede previous schema configuration. This allows for optional overrides if necessary.

const person = object({
  name: string().required(),
  age: number().required(),
  legalGuardian:  string().when('age', {
    is: (age) => age != null && age < 18,
    then: (schema) => schema.required(),
  }),
});

const optionalPerson = person.partial()

person.cast({name: 'James', age: 6 }) // => TypeError legalGuardian required

// age is still required b/c it's applied after the `partial`
optionalPerson.cast({name: 'James',  age: 6 }) // => TypeError legalGuardian required

This works slightly differently for lazy which have no schema to "start" with:

const config = object({
  nameOrIdNumber:  lazy((value) => {
     if (typeof value === 'number') return number().required()
     return string().required()
  }),
});

const opti = config.partial()

config.cast({}) // => TypeError nameOrIdNumber is required

config.partial().cast({}) // => {}

Cast optionality migration path

A larger breaking change in v1 is the assertion of optionality during cast, making previous patterns like string().nullable().required() no longer possible. Generally this pattern is used when deserialized data is not valid to start, but will become valid through user input such as with an HTML form. v1 no longer allows this, but in order to make migration easier we've added an option to cast that mimics the previous behavior (not exactly but closely).

const name = string().required()

name.cast(null, { assert: 'ignore-optionality'}) // => null

We recommend updating your schema to new patterns where possible but this allows for incremental upgrades

What's Changed

• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1630
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1652
• fix(docs): correct typo "coarce" to "coerce" by @eunicode in https://github.com/jquense/yup/pull/1654
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1656
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1665
• Capitalize two words in README by @Glitchy-Tozier in https://github.com/jquense/yup/pull/1676
• Fix typo by @karlhorky in https://github.com/jquense/yup/pull/1672
• Show example of function message by @karlhorky in https://github.com/jquense/yup/pull/1674
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1678
• Fix typo: coarce -> coerce by @karlhorky in https://github.com/jquense/yup/pull/1677
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1685
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1692
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1697
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1699
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1709
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1714
• Fix Typo : delete duplicate word "passed" by @ANTARES-KOR in https://github.com/jquense/yup/pull/1696
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1722
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1727
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1731
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1737
• chore(deps): update all non-major dependencies by @renovate in https://github.com/jquense/yup/pull/1744
• small typo fix by @somodis in https://github.com/jquense/yup/pull/1745
• feat: better Lazy types and deepPartial fixes by @jquense in https://github.com/jquense/yup/pull/1748
• feat: add cast nullability migration path. by @jquense in https://github.com/jquense/yup/pull/1749

New Contributors

• @eunicode made their first contribution in https://github.com/jquense/yup/pull/1654
• @Glitchy-Tozier made their first contribution in https://github.com/jquense/yup/pull/1676
• @karlhorky made their first contribution in https://github.com/jquense/yup/pull/1672
• @ANTARES-KOR made their first contribution in https://github.com/jquense/yup/pull/1696
• @somodis made their first contribution in https://github.com/jquense/yup/pull/1745

Full Changelog: https://github.com/jquense/yup/compare/v1.0.0-beta.4...v1.0.0-beta.5