migrating-to-universal-types.md

Migrating to Universal Types

Old syntax	New syntax
stringType	string()1
numberType	number()1
booleanType	boolean()1
dateType	date()1
oneOfType('foo', 'bar')	union(['foo', 'bar'])1
stringType('')	string().default('')12
stringType(throwable)	string().defined()12
arrayOfType(stringType)	string().array()/string().defined().array()13
arrayOfType(stringType(''))	string().default('').array()124
arrayOfType(stringType(throwable))	string().defined().array()1245
arrayOfType(/* */)([])	N/A6
arrayOfType(/* */)(throwable)	N/A6

For additional info, check out Advanced examples in the README.

Footnotes

1. With new syntax, for state fields, the value (or its parts) is not stringified or parsed (i.e. only validated). ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰

2. With old syntax, custom types could technically allow undefined, in which case throwable and a fallback value wouldn't be used for absent values. With new syntax, undefined can't be returned if .default() or .defined() are used. ↩ ↩² ↩³ ↩⁴

3. With old syntax, any invalid item fails the whole array, and that error is replaced with undefined. There is no equivalent new syntax, but string().array() should be more useful. It always returns an array, and invalid items are replaced with undefined (as of v2.0.0, undefined values are omitted). If you need to fail the whole array, the closest new syntax is string().defined().array(), which throws an error if any item is absent or invalid (though it's not very useful). ↩

4. With new syntax, array is always defined. ↩ ↩²

5. This old syntax is unintuitive and unintentional, and therefore shouldn't be used at all. ↩

6. With new syntax, there are no tweaks on the array level because it's always defined and the only way to throw an error is to do it on the item level. ↩ ↩²