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Function: fromPredicateWithError()

fromPredicateWithError<T, E>(predicate, getError): Validator<T, T, E>

Defined in: validation/constructors/index.ts:139

Creates a validator from a predicate with a dynamic error function.

Like fromPredicate, but allows the error message to depend on the input value.

Type Parameters​

T​

T

E​

E

Parameters​

predicate​

Predicate<T>

Function that tests the value

getError​

(value) => E

Function that generates the error from the value

Returns​

Validator<T, T, E>

A validator function

Example​

// Dynamic error message
const minLength = (min: number) =>
  fromPredicateWithError(
    (s: string) => s.length >= min,
    (s) => `Expected ${min} characters, got ${s.length}`
  )

minLength(5)('hi')
// => Invalid(['Expected 5 characters, got 2'])

// Real-world: Range validation with context
const inRange = (min: number, max: number) =>
  fromPredicateWithError(
    (n: number) => n >= min && n <= max,
    (n) => `${n} is out of range [${min}, ${max}]`
  )

See​

fromPredicate - for static error messages