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Built-in Validators

All validators are imported from reformer/validators.

required​

Field must have a non-empty value.

import { required } from '@reformer/core/validators';

required(path.name);
// Error: { code: 'required', message: '...' }

Empty values: '', null, undefined, []

email​

Valid email format.

import { email } from '@reformer/core/validators';

email(path.email);
// Error: { code: 'email', message: '...' }

minLength / maxLength​

String length constraints.

import { minLength, maxLength } from '@reformer/core/validators';

minLength(path.name, 2);
// Error: { code: 'minLength', params: { required: 2, actual: 1 } }

maxLength(path.bio, 500);
// Error: { code: 'maxLength', params: { required: 500, actual: 501 } }

min / max​

Number value constraints.

import { min, max } from '@reformer/core/validators';

min(path.age, 18);
// Error: { code: 'min', params: { min: 18, actual: 16 } }

max(path.quantity, 100);
// Error: { code: 'max', params: { max: 100, actual: 150 } }

pattern​

Match regex pattern.

import { pattern } from '@reformer/core/validators';

// Only letters
pattern(path.code, /^[A-Z]+$/);
// Error: { code: 'pattern', params: { pattern: '/^[A-Z]+$/' } }

// Custom error key
pattern(path.code, /^[A-Z]+$/, 'uppercase');
// Error: { code: 'uppercase' }

url​

Valid URL format.

import { url } from '@reformer/core/validators';

url(path.website);
// Error: { code: 'url', message: '...' }

phone​

Valid phone number format.

import { phone } from '@reformer/core/validators';

phone(path.phone);
// Error: { code: 'phone', message: '...' }

number​

Must be a valid number.

import { number } from '@reformer/core/validators';

number(path.amount);
// Error: { code: 'number', message: '...' }

date​

Valid date value.

import { date } from '@reformer/core/validators';

date(path.birthDate);
// Error: { code: 'date', message: '...' }

Combining Validators​

Apply multiple validators to one field:

validation: (path) => {
  required(path.password);
  minLength(path.password, 8);
  pattern(path.password, /[A-Z]/, 'uppercase');
  pattern(path.password, /[0-9]/, 'hasNumber');
};

All validators run, errors are collected:

// If password is "abc"
errors: [
  { code: 'minLength', params: { required: 8, actual: 3 } },
  { code: 'uppercase' },
  { code: 'hasNumber' },
];

Next Steps​