Constraint Pipeline

Low-level building blocks used internally by validateObject. Export them when you need custom field validation logic without the full validator.

import {
  constraintsFromSchema, composeConstraints, applyTransform,
  checkType, checkMinLength, checkMaxLength,
  checkMinimum, checkMaximum, checkFormat,
  checkPattern, checkEnum,
  PATTERN_MAX_INPUT_LENGTH, DEFAULT_MESSAGES,
} from '@uuki/schemable-validator-client'

---

constraintsFromSchema(schema)

Build a single composed Constraint from a PropertySchema. This is the same function validateObject calls internally.

import { constraintsFromSchema } from '@uuki/schemable-validator-client'
import type { PropertySchema } from '@uuki/schemable-validator-client'

const schema: PropertySchema = { type: 'string', format: 'email', minLength: 5 }
const validate = constraintsFromSchema(schema)

const result = validate({ value: 'bad', errors: [] })
// { value: 'bad', errors: ['must be a valid email'] }

---

composeConstraints(constraints)

Combine an array of Constraint functions into one. All constraints run in order, accumulating every error (no short-circuit).

import { composeConstraints, checkMinLength, checkFormat } from '@uuki/schemable-validator-client'

const validate = composeConstraints([
  checkMinLength(3),
  checkFormat('email'),
])

validate({ value: 'x', errors: [] })
// { value: 'x', errors: [
//     'must be at least 3 characters long',
//     'must be a valid email'
//   ] }

---

applyTransform(value, transforms)

Apply the x-transform catalog transforms to a string value before validation. Returns the transformed string.

Supported transforms: trim, toLowerCase, toUpperCase.

import { applyTransform } from '@uuki/schemable-validator-client'

applyTransform('  Hello World  ', ['trim', 'toLowerCase'])
// 'hello world'

---

Individual constraint factories

Each factory returns a Constraint -- (state: FieldState) => FieldState. All factories accept an optional trailing message? parameter to override the default error text from DEFAULT_MESSAGES.

Function	Description
checkType(type, message?)	Validates integer / number / boolean coercion. Strings are always accepted.
checkMinLength(min, message?)	String length >= min.
checkMaxLength(max, message?)	String length <= max.
checkMinimum(min, message?)	Numeric value >= min.
checkMaximum(max, message?)	Numeric value <= max.
checkFormat(format, message?)	Matches one of the built-in format regexes (see table below).
checkPattern(pattern, maxLen?, message?)	Tests against a user-supplied regex string. Inputs longer than maxLen (default 500) are skipped to prevent ReDoS.
checkEnum(values, message?)	Value must be in the given list.

Built-in formats for checkFormat

Format	Pattern
email	local@domain.tld -- rejects control chars and zero-width Unicode
uri	https?://... -- rejects control chars
date	YYYY-MM-DD
date-time	YYYY-MM-DDTHH:MM:SS[.ms](Z|+-HH:MM)
time	HH:MM:SS[.ms][Z|+-HH:MM]
uuid	RFC 4122
ipv4	dotted-decimal
ipv6	full / compressed
hostname	label.label.tld

import { checkFormat, checkMinLength, composeConstraints } from '@uuki/schemable-validator-client'

const emailField = composeConstraints([checkMinLength(1), checkFormat('email')])

emailField({ value: '', errors: [] })
// { value: '', errors: ['must be at least 1 character long'] }

emailField({ value: 'not-an-email', errors: [] })
// { value: 'not-an-email', errors: ['must be a valid email'] }

---

DEFAULT_MESSAGES and substituteVars

DEFAULT_MESSAGES is a frozen catalog of default error strings keyed by rule name (required, minLength, email, etc.). Override individual messages via the message? parameter on each constraint factory, or via the errorMessage property on PropertySchema.

Message templates use {var} placeholders (an ICU subset) resolved by substituteVars. For example, 'must be at least {min} character{plural} long' is interpolated at runtime with the constraint's actual values.

---

PATTERN_MAX_INPUT_LENGTH

export const PATTERN_MAX_INPUT_LENGTH = 500

The default maximum input length before checkPattern skips client-side regex evaluation. Override per-call:

import { checkPattern } from '@uuki/schemable-validator-client'

// Always evaluate, regardless of length
const strictSlug = checkPattern('^[a-z0-9-]+$', Infinity)