Version: 7.0.0

`ValidationChain`

The validation chain contains all of the built-in validators, sanitizers and utility methods to fine tune the behaviour of the validation for a certain field or fields.

Validation chains are created by the check() functions, and they can be used in a few ways:

as express.js route handlers, which will run the validation automatically;
as parameter of some of express-validator's other functions, like oneOf() or checkExact();
standalone, where you have full control over when the validation runs and how.

tip

If you're writing a function that accepts a ValidationChain, the TypeScript type can be imported using

import { ValidationChain } from 'express-validator';

Built-in validators

`.custom()`

custom(validator: (value, { req, location, path }) => any): ValidationChain

Adds a custom validator function to the chain.

The field value will be valid if:

The custom validator returns truthy; or
The custom validator returns a promise that resolves.

If the custom validator returns falsy, a promise that rejects, or if the function throws, then the value will be considered invalid.

A common use case for .custom() is to verify that an e-mail address doesn't already exists. If it does, return an error:

app.post(
  '/signup',
  body('email').custom(async value => {
    const existingUser = await Users.findUserByEmail(value);
    if (existingUser) {
      throw new Error('E-mail already in use');
    }
  }),
  (req, res) => {
    // Handle request
  },
);

`.exists()`

exists(options?: {
  values?: 'undefined' | 'null' | 'falsy',
  checkNull?: boolean,
  checkFalsy?: boolean
}): ValidationChain

Adds a validator to check if the field exists.

Which values are considered existent depends on options.values. By default, it's set to undefined:

`options.values`	Behavior
`undefined`	`undefined` values don't exist
`null`	`undefined` and `null` values don't exist
`falsy`	Falsy values (empty strings, `0`, `false`, `null` and `undefined` values don't exist

options.checkNull and options.checkFalsy are deprecated options. They are aliases to setting options.values to null and falsy, respectively.

note

Using .exists() is only necessary if you aren't adding any other validator or sanitizer.

`.isArray()`

isArray(options?: { min?: number; max?: number }): ValidationChain

Adds a validator to check that a value is an array. This is analogous to the JavaScript function Array.isArray(value).

You can also check that the array's length is greater than or equal to options.min and/or that it's less than or equal to options.max.

// Verifies that the friends list is an array
body('friends').isArray();

// Verifies that ingredients is an array with length >= 0
body('ingredients').isArray({ min: 0 });

// Verifies that team_members is an array with length >= 0 and <= 10
check('team_members').isArray({ min: 0, max: 10 });

`.isObject()`

isObject(options?: { strict?: boolean }): ValidationChain

Adds a validator to check that a value is an object. For example, {}, { foo: 'bar' } and new MyCustomClass() would all pass this validator.

If the strict option is set to false, then this validator works analogous to typeof value === 'object' in pure JavaScript, where both arrays and the null value are considered objects.

`.isString()`

isString(): ValidationChain

Adds a validator to check that a value is a string. This is analogous to a typeof value === 'string' in pure JavaScript.

`.notEmpty()`

notEmpty(): ValidationChain

Adds a validator to check that a value is a string that's not empty. This is analogous to .not().isEmpty().

Standard validators

info

Please check the documentation on standard validators here.

`contains()`

contains(elem: any, options?: {
  ignoreCase?: boolean;
  minOccurrences?: number;
}): ValidationChain

`equals()`

equals(comparison: string): ValidationChain

`isAfter()`

isAfter(dateOrOptions?: string | {
  comparisonDate?: string;
}): ValidationChain

`isAlpha()`

isAlpha(locale?: AlphaLocale, options?: {
  ignore?: string | string[] | RegExp;
}): ValidationChain

Possible values of AlphaLocale

'ar'
'ar-AE'
'ar-BH'
'ar-DZ'
'ar-EG'
'ar-IQ'
'ar-JO'
'ar-KW'
'ar-LB'
'ar-LY'
'ar-MA'
'ar-QA'
'ar-QM'
'ar-SA'
'ar-SD'
'ar-SY'
'ar-TN'
'ar-YE'
'az-AZ'
'bg-BG'
'bn-BD'
'cs-CZ'
'da-DK'
'de-DE'
'el-GR'
'en-AU'
'en-GB'
'en-HK'
'en-IN'
'en-NZ'
'en-US'
'en-ZA'
'en-ZM'
'es-ES'
'fa-AF'
'fa-IR'
'fi-FI'
'fr-FR'
'he'
'hi-IN'
'hu-HU'
'id-ID'
'it-IT'
'ja-JP'
'ko-KR'
'ku-IQ'
'nb-NO'
'nl-NL'
'nn-NO'
'pl-PL'
'pt-BR'
'pt-PT'
'ru-RU'
'si-LK'
'sk-SK'
'sl-SI'
'sr-RS'
'sr-RS@latin'
'sv-SE'
'th-TH'
'tr-TR'
'uk-UA'
'vi-VN'

`isAlphanumeric()`

isAlphanumeric(locale?: AlphanumericLocale, options?: {
  ignore?: string | RegExp;
}): ValidationChain

Possible values of AlphanumericLocale

'ar'
'ar-AE'
'ar-BH'
'ar-DZ'
'ar-EG'
'ar-IQ'
'ar-JO'
'ar-KW'
'ar-LB'
'ar-LY'
'ar-MA'
'ar-QA'
'ar-QM'
'ar-SA'
'ar-SD'
'ar-SY'
'ar-TN'
'ar-YE'
'az-AZ'
'bg-BG'
'bn-BD'
'cs-CZ'
'da-DK'
'de-DE'
'el-GR'
'en-AU'
'en-GB'
'en-HK'
'en-IN'
'en-NZ'
'en-US'
'en-ZA'
'en-ZM'
'es-ES'
'fa-AF'
'fa-IR'
'fi-FI'
'fr-FR'
'fr-BE'
'he'
'hi-IN'
'hu-HU'
'it-IT'
'id-ID'
'ja-JP'
'ko-KR'
'ku-IQ'
'nb-NO'
'nl-BE'
'nl-NL'
'nn-NO'
'pl-PL'
'pt-BR'
'pt-PT'
'ru-RU'
'si-LK'
'sk-SK'
'sl-SI'
'sr-RS'
'sr-RS@latin'
'sv-SE'
'th-TH'
'tr-TR'
'uk-UA'
'vi-VN'

`isAscii()`

isAscii(): ValidationChain

`isBase32()`

isBase32(options?: {
  crockford?: boolean;
}): ValidationChain

`isBase58()`

isBase58(): ValidationChain

`isBase64()`

isBase64(options?: {
  urlSafe?: boolean;
}): ValidationChain

`isBefore()`

isBefore(date?: string): ValidationChain

`isBIC()`

isBIC(): ValidationChain

`isBoolean()`

isBoolean(options?: {
  strict?: boolean;
  loose?: boolean;
}): ValidationChain

`isBtcAddress()`

isBtcAddress(): ValidationChain

`isByteLength()`

isByteLength(options: {
  min?: number;
  max?: number;
  lt?: number;
  gt?: number;
}): ValidationChain

`isCreditCard()`

isCreditCard(options?: {
  provider?: 'amex' | 'dinersclub' | 'discover' | 'jcb' | 'mastercard' | 'unionpay' | 'visa';
}): ValidationChain

`isCurrency()`

isCurrency(options?: {
  symbol?: string;
  require_symbol?: boolean;
  allow_space_after_symbol?: boolean;
  symbol_after_digits?: boolean;
  allow_negatives?: boolean;
  parens_for_negatives?: boolean;
  negative_sign_before_digits?: boolean;
  negative_sign_after_digits?: boolean;
  allow_negative_sign_placeholder?: boolean;
  thousands_separator?: string;
  decimal_separator?: string;
  allow_decimal?: boolean;
  require_decimal?: boolean;
  digits_after_decimal?: number[];
  allow_space_after_digits?: boolean;
}): ValidationChain

`isDataURI()`

isDataURI(): ValidationChain

`isDate()`

isDate(options?: {
  format?: string;
  delimiters?: string[];
  strictMode?: boolean;
}): ValidationChain

`isDecimal()`

isDecimal(options?: {
  decimal_digits?: string;
  force_decimal?: boolean;
  locale?: AlphanumericLocale;
  blacklisted_chars?: string;
}): ValidationChain

`isDivisibleBy()`

isDivisibleBy(number: number): ValidationChain

`isEAN()`

isEAN(): ValidationChain

`isEmail()`

isEmail(options?: {
  allow_display_name?: boolean;
  allow_utf8_local_part?: boolean;
  require_tld?: boolean;
  ignore_max_length?: boolean;
  allow_ip_domain?: boolean;
  domain_specific_validation?: boolean;
  blacklisted_chars?: string;
  host_blacklist?: string[];
  host_whitelist?: string[];
}): ValidationChain

`isEmpty()`

isEmpty(options?: {
  ignore_whitespace: boolean;
}): ValidationChain

`isEthereumAddress()`

isEthereumAddress(): ValidationChain

`isFQDN()`

isFQDN(options?: {
  require_tld?: boolean;
  allow_underscores?: boolean;
  allow_trailing_dot?: boolean;
  allow_numeric_tld?: boolean;
  allow_wildcard?: boolean;
  ignore_max_length?: boolean;
}): ValidationChain

`isFloat()`

isFloat(options?: {
  min?: number;
  max?: number;
  lt?: number;
  gt?: number;
  locale?: AlphanumericLocale;
}): ValidationChain

`isFullWidth()`

isFullWidth(): ValidationChain

`isHalfWidth()`

isHalfWidth(): ValidationChain

`isHash()`

isHash(algorithm: HashAlgorithm): ValidationChain

Possible values of HashAlgorithm

'md4'
'md5'
'sha1'
'sha256'
'sha384'
'sha512'
'ripemd128'
'ripemd160'
'tiger128'
'tiger160'
'tiger192'
'crc32'
'crc32b'

`isHexColor()`

isHexColor(): ValidationChain

`isHexadecimal()`

isHexadecimal(): ValidationChain

`isHSL()`

isHSL(): ValidationChain

`isIBAN()`

isIBAN(): ValidationChain

`isIdentityCard()`

isIdentityCard(locale?: IdentityCardLocale): ValidationChain

Possible values of IdentityCardLocale

'any'
'ar-LY'
'ar-TN'
'ES'
'FI'
'he-IL'
'hk-HK'
'IN'
'IT'
'IR'
'MZ'
'NO'
'PL'
'TH'
'zh-CN'
'zh-TW'

`isIMEI()`

isIMEI(options?: {
  allow_hyphens?: boolean;
}): ValidationChain

`isIP()`

isIP(version?: 4 | 6): ValidationChain

`isIPRange()`

isIPRange(version?: 4 | 6): ValidationChain

`isISBN()`

isISBN(versionOrOptions?: number | {
  version?: '10' | '13';
}): ValidationChain

`isISSN()`

isISSN(options?: {
  case_sensitive?: boolean;
  require_hyphen?: boolean;
}): ValidationChain

`isISIN()`

isISIN(): ValidationChain

`isISO6391()`

isISO6391(): ValidationChain

`isISO8601()`

isISO8601(options?: {
  strict?: boolean;
  strictSeparator?: boolean;
}): ValidationChain

`isISO31661Alpha2()`

isISO31661Alpha2(): ValidationChain

`isISO31661Alpha3()`

isISO31661Alpha3(): ValidationChain

`isISO4217()`

isISO4217(): ValidationChain

`isISRC()`

isISRC(): ValidationChain

`isIn()`

isIn(values: readonly any[]): ValidationChain

`isInt()`

isInt(options?: {
  min?: number;
  max?: number;
  lt?: number;
  gt?: number;
  allow_leading_zeroes?: boolean;
}): ValidationChain

`isJSON()`

isJSON(options?: {
  allow_primitives?: boolean;
}): ValidationChain

`isJWT()`

isJWT(): ValidationChain

`isLatLong()`

isLatLong(options?: {
  checkDMS?: boolean;
}): ValidationChain

`isLength()`

isLength(options: {
  min?: number;
  max?: number;
}): ValidationChain

`isLicensePlate()`

isLicensePlate(locale: IsLicensePlateLocale): ValidationChain

Possible values of IsLicensePlateLocale

'cs-CZ'
'de-DE'
'de-LI'
'en-NI'
'es-AR'
'fi-FI'
'hu-HU'
'pt-BR'
'pt-PT'
'sq-AL'
'sv-SE'
'any'

`isLocale()`

isLocale(): ValidationChain

`isLowercase()`

isLowercase(): ValidationChain

`isLuhnNumber()`

isLuhnNumber(): ValidationChain

`isMagnetURI()`

isMagnetURI(): ValidationChain

`isMACAddress()`

isMACAddress(options?: {
  no_separators?: boolean;
  no_colons?: boolean;
  eui?: '48' | '64';
}): ValidationChain

`isMD5()`

isMD5(): ValidationChain

`isMimeType()`

isMimeType(): ValidationChain

`isMobilePhone()`

isMobilePhone(locale: MobilePhoneLocale | readonly Options.MobilePhoneLocale[], options?: {
  strictMode?: boolean;
}): ValidationChain

Possible values of MobilePhoneLocale

'any'
'am-AM'
'ar-AE'
'ar-BH'
'ar-DZ'
'ar-EG'
'ar-EH'
'ar-IQ'
'ar-JO'
'ar-KW'
'ar-LB'
'ar-LY'
'ar-MA'
'ar-OM'
'ar-PS'
'ar-SA'
'ar-SY'
'ar-TN'
'ar-YE'
'az-AZ'
'be-BY'
'bg-BG'
'bn-BD'
'bs-BA'
'cs-CZ'
'de-AT'
'de-CH'
'de-DE'
'de-LU'
'da-DK'
'dv-MV'
'dz-BT'
'el-CY'
'el-GR'
'en-AG'
'en-AI'
'en-AU'
'en-BM'
'en-BS'
'en-BW'
'en-CA'
'en-GB'
'en-GG'
'en-GH'
'en-GY'
'en-HK'
'en-HN'
'en-IE'
'en-IN'
'en-JM'
'en-KE'
'en-KI'
'en-KN'
'en-LS'
'en-MT'
'en-MU'
'en-NA'
'en-NG'
'en-NZ'
'en-PG'
'en-PH'
'en-PK'
'en-RW'
'en-SG'
'en-SL'
'en-SS'
'en-TZ'
'en-UG'
'en-US'
'en-ZA'
'en-ZM'
'en-ZW'
'es-AR'
'es-BO'
'es-CL'
'es-CO'
'es-CR'
'es-CU'
'es-DO'
'es-EC'
'es-ES'
'es-HN'
'es-MX'
'es-NI'
'es-PA'
'es-PE'
'es-PY'
'es-SV'
'es-UY'
'es-VE'
'et-EE'
'fa-AF'
'fa-IR'
'fi-FI'
'fj-FJ'
'fo-FO'
'fr-BE'
'fr-BF'
'fr-BJ'
'fr-CD'
'fr-CH'
'fr-CM'
'fr-FR'
'fr-GF'
'fr-GP'
'fr-MQ'
'fr-PF'
'fr-RE'
'ga-IE'
'he-IL'
'hu-HU'
'id-ID'
'ir-IR'
'it-CH'
'it-IT'
'it-SM'
'ja-JP'
'ka-GE'
'kk-KZ'
'kl-GL'
'ko-KR'
'ky-KG'
'lt-LT'
'lv-LV'
'mg-MG'
'mn-MN'
'ms-MY'
'my-MM'
'mz-MZ'
'nb-NO'
'nl-AW'
'nl-BE'
'nl-NL'
'ne-NP'
'nn-NO'
'pl-PL'
'pt-AO'
'pt-BR'
'pt-PT'
'ro-MD'
'ro-RO'
'ru-RU'
'si-LK'
'sk-SK'
'sl-SI'
'sq-AL'
'sr-RS'
'sv-SE'
'tg-TJ'
'th-TH'
'tk-TM'
'tr-TR'
'uk-UA'
'uz-Uz'
'vi-VN'
'zh-CN'
'zh-HK'
'zh-TW'

`isMongoId()`

isMongoId(): ValidationChain

`isMultibyte()`

isMultibyte(): ValidationChain

`isNumeric()`

isNumeric(options?: {
  no_symbols: boolean;
  locale?: AlphanumericLocale;
}): ValidationChain

`isOctal()`

isOctal(): ValidationChain

`isPassportNumber()`

isPassportNumber(countryCode?: PassportCountryCode): ValidationChain

Possible values of PassportCountryCode

'AM'
'AR'
'AT'
'AU'
'AZ'
'BE'
'BG'
'BY'
'BR'
'CA'
'CH'
'CN'
'CY'
'CZ'
'DE'
'DK'
'DZ'
'EE'
'ES'
'FI'
'FR'
'GB'
'GR'
'HR'
'HU'
'ID'
'IE'
'IN'
'IR'
'IS'
'IT'
'JM'
'JP'
'KR'
'KZ'
'LI'
'LT'
'LU'
'LV'
'LY'
'MT'
'MY'
'MZ'
'NL'
'NZ'
'PH'
'PK'
'PL'
'PO'
'PT'
'RO'
'RU'
'SE'
'SL'
'SK'
'TH'
'TR'
'UA'
'US'

`isPort()`

isPort(): ValidationChain

`isPostalCode()`

isPostalCode(locale: PostalCodeLocale): ValidationChain

Possible values of PostalCodeLocale

'any'
'AD'
'AT'
'AU'
'AZ'
'BA'
'BE'
'BG'
'BR'
'BY'
'CA'
'CH'
'CN'
'CZ'
'DE'
'DK'
'DO'
'DZ'
'EE'
'ES'
'FI'
'FR'
'GB'
'GR'
'HR'
'HT'
'HU'
'ID'
'IL'
'IN'
'IR'
'IS'
'IT'
'JP'
'KE'
'KR'
'LI'
'LK'
'LT'
'LU'
'LV'
'MT'
'MX'
'MY'
'NL'
'NO'
'NP'
'NZ'
'PL'
'PR'
'PT'
'RO'
'RU'
'SA'
'SE'
'SG'
'SI'
'SK'
'TH'
'TN'
'TW'
'UA'
'US'
'ZA'
'ZM'

`isRgbColor()`

isRgbColor(includePercentValues?: boolean): ValidationChain

`isRFC3339()`

isRFC3339(): ValidationChain

`isSemVer()`

isSemVer(): ValidationChain

`isSlug()`

isSlug(): ValidationChain

`isStrongPassword()`

isStrongPassword(options?: {
  minLength?: number;
  minLowercase?: number;
  minUppercase?: number;
  minNumbers?: number;
  minSymbols?: number;
  returnScore?: boolean;
  pointsPerUnique?: number;
  pointsPerRepeat?: number;
  pointsForContainingLower?: number;
  pointsForContainingUpper?: number;
  pointsForContainingNumber?: number;
  pointsForContainingSymbol?: number;
}): ValidationChain

`isSurrogatePair()`

isSurrogatePair(): ValidationChain

`isTaxID()`

isTaxID(locale: TaxIDLocale): ValidationChain

Possible values of TaxIDLocale

'bg-BG'
'cs-CZ'
'de-AT'
'de-DE'
'dk-DK'
'el-CY'
'el-GR'
'en-CA'
'en-GB'
'en-IE'
'en-US'
'es-ES'
'et-EE'
'fi-FI'
'fr-BE'
'fr-FR'
'fr-LU'
'hr-HR'
'hu-HU'
'it-IT'
'lb-LU'
'lt-LT'
'lv-LV'
'mt-MT'
'nl-BE'
'nl-NL'
'pl-PL'
'pt-BR'
'pt-PT'
'ro-RO'
'sk-SK'
'sl-SI'
'sv-SE'

`isTime()`

isTime(options: {
  hourFormat?: 'hour24' | 'hour12';
  mode?: 'default' | 'withSeconds';
}): ValidationChain

`isURL()`

isURL(options?: {
  protocols?: URLProtocol[];
  require_tld?: boolean;
  require_protocol?: boolean;
  require_host?: boolean;
  require_port?: boolean;
  require_valid_protocol?: boolean;
  allow_underscores?: boolean;
  host_whitelist?: (string | RegExp)[];
  host_blacklist?: (string | RegExp)[];
  allow_trailing_dot?: boolean;
  allow_protocol_relative_urls?: boolean;
  disallow_auth?: boolean;
  validate_length?: boolean;
  allow_fragments?: boolean;
  allow_query_components?: boolean;
}): ValidationChain

`isUUID()`

isUUID(version?: UUIDVersion): ValidationChain

Possible values of UUIDVersion

1
2
3
4
5
'1'
'2'
'3'
'4'
'5'
'all'

`isUppercase()`

isUppercase(): ValidationChain

`isVariableWidth()`

isVariableWidth(): ValidationChain

`isVAT()`

isVAT(countryCode: VATCountryCode): ValidationChain

Possible values of VATCountryCode

'GB'
'IT'
'NL'
'AT'
'BE'
'BG'
'HR'
'CY'
'CZ'
'DK'
'EE'
'FI'
'FR'
'DE'
'EL'
'HU'
'IE'
'LV'
'LT'
'LU'
'MT'
'PL'
'PT'
'RO'
'SK'
'SI'
'ES'
'SE'
'AL'
'MK'
'AU'
'BY'
'CA'
'IS'
'IN'
'ID'
'IL'
'KZ'
'NZ'
'NG'
'NO'
'PH'
'RU'
'SM'
'SA'
'RS'
'CH'
'TR'
'UA'
'UZ'
'AR'
'BO'
'BR'
'CL'
'CO'
'CR'
'EC'
'SV'
'GT'
'HN'
'MX'
'NI'
'PA'
'PY'
'PE'
'DO'
'UY'
'VE'

`isWhitelisted()`

isWhitelisted(chars: string | readonly string[]): ValidationChain

`matches()`

matches(pattern: RegExp | string, modifiers?: string): ValidationChain

Built-in sanitizers

`.customSanitizer()`

customSanitizer(sanitizer: (value, { req, location, path }) => any): ValidationChain

Adds a custom sanitizer function to the chain. The value returned by the function will become the new value of the field.

app.post('/object/:id', param('id').customSanitizer((value, { req }) => {
  // In this app, users have MongoDB style object IDs, everything else, numbers
  return req.query.type === 'user' ? ObjectId(value) : Number(value);
})), (req, res) => {
  // Handle request
});

`.default()`

default(defaultValue: any): ValidationChain

Replaces the value of the field if it's either an empty string, null, undefined, or NaN.

app.post('/', body('username').default('foo'), (req, res, next) => {
  // 'bar'     => 'bar'
  // ''        => 'foo'
  // undefined => 'foo'
  // null      => 'foo'
  // NaN       => 'foo'
});

`.replace()`

replace(valuesFrom: any[], valueTo: any): ValidationChain

Replaces the value of the field with valueTo whenever the current value is in valuesFrom.

app.post('/', body('username').replace(['bar', 'BAR'], 'foo'), (req, res, next) => {
  // 'bar_' => 'bar_'
  // 'bar'  => 'foo'
  // 'BAR'  => 'foo'
  console.log(req.body.username);
});

`.toArray()`

toArray(): ValidationChain

Transforms the value to an array. If it already is one, nothing is done. undefined values become empty arrays.

`.toLowerCase()`

toLowerCase(): ValidationChain

Converts the value to lower case. If not a string, does nothing.

`.toUpperCase()`

toUpperCase(): ValidationChain

Converts the value to upper case. If not a string, does nothing.

Standard sanitizers

info

Please check the documentation on standard sanitizers here.

`blacklist()`

blacklist(chars: string): ValidationChain

`escape()`

escape(): ValidationChain

`unescape()`

unescape(): ValidationChain

`ltrim()`

ltrim(chars?: string): ValidationChain

`normalizeEmail()`

normalizeEmail(options?: {
  all_lowercase?: boolean;
  gmail_lowercase?: boolean;
  gmail_remove_dots?: boolean;
  gmail_remove_subaddress?: boolean;
  gmail_convert_googlemaildotcom?: boolean;
  outlookdotcom_lowercase?: boolean;
  outlookdotcom_remove_subaddress?: boolean;
  yahoo_lowercase?: boolean;
  yahoo_remove_subaddress?: boolean;
  icloud_lowercase?: boolean;
  icloud_remove_subaddress?: boolean;
}): ValidationChain

`rtrim()`

rtrim(chars?: string): ValidationChain

`stripLow()`

stripLow(keep_new_lines?: boolean): ValidationChain

`toBoolean()`

toBoolean(strict?: boolean): ValidationChain

`toDate()`

toDate(): ValidationChain

`toFloat()`

toFloat(): ValidationChain

`toInt()`

toInt(radix?: number): ValidationChain

`trim()`

trim(chars?: string): ValidationChain

`whitelist()`

whitelist(chars: string): ValidationChain

Modifiers

`.bail()`

bail(options?: { level: 'chain' | 'request' }): ValidationChain

Parameters:

Name	Description
`options.level`	The level at which the validation chain should be stopped. Defaults to `chain`.

Stops running the validation chain if any of the previous validators failed.

This is useful to prevent a custom validator that touches a database or external API from running when you know it will fail.

.bail() can be used multiple times in the same validation chain if desired:

body('username')
  .isEmail()
  // If not an email, stop here
  .bail()
  .custom(checkDenylistDomain)
  // If domain is not allowed, don't go check if it already exists
  .bail()
  .custom(checkEmailExists);

If the level option is set to request, then also no further validation chains will run on the current request. For example:

app.get(
  '/search',
  query('query').notEmpty().bail({ level: 'request' }),
  // If `query` is empty, then the following validation chains won't run:
  query('query_type').isIn(['user', 'posts']),
  query('num_results').isInt(),
  (req, res) => {
    // Handle request
  },
);

caution

Functions such as oneOf() and checkExact() can become slower when using request-level bail, since validation chains that would normally run in parallel need to run in sequence.

`.if()`

if(condition: CustomValidator | ContextRunner): ValidationChain

Adds a condition on whether the validation chain should continue running on a field or not.

The condition may be either a custom validator or a ContextRunner instance.

body('newPassword')
  // Only validate if the old password has been provided
  .if((value, { req }) => req.body.oldPassword)
  // Or, use a validation chain instead
  .if(body('oldPassword').notEmpty())
  // The length of the new password will only be checked if `oldPassword` is provided.
  .isLength({ min: 6 });

`.not()`

not(): ValidationChain

Negates the result of the next validator in the chain.

check('weekday').not().isIn(['sunday', 'saturday']);

`.optional()`

optional(options?: boolean | {
  values?: 'undefined' | 'null' | 'falsy',
  nullable?: boolean,
  checkFalsy?: boolean,
}): ValidationChain

Marks the current validation chain as optional. An optional field skips validation depending on its value, instead of failing it.

Which values are considered optional depends on options.values. By default, it's set to undefined:

`options.values`	Behavior
`undefined`	`undefined` values are optional
`null`	`undefined` and `null` values are optional
`falsy`	Falsy values (empty strings, `0`, `false`, `null` and `undefined` values are optional

options.nullable and options.checkFalsy are deprecated options. They are aliases to setting options.values to null or falsy.

If options is false, then the field won't be optional.

info

Unlike validators and sanitizers, .optional() is not positional: it'll affect how values are interpreted, no matter where it happens in the chain.

For example, there are no differences between this:

body('json_string').isLength({ max: 100 }).isJSON().optional().

and this:

body('json_string').optional().isLength({ max: 100 }).isJSON().

`.withMessage()`

withMessage(message: any): ValidationChain

Sets the error message used by the previous validator.

ValidationChain

Built-in validators​

.custom()​

.exists()​

.isArray()​

.isObject()​

.isString()​

.notEmpty()​

Standard validators​

contains()​

equals()​

isAfter()​

isAlpha()​

isAlphanumeric()​

isAscii()​

isBase32()​

isBase58()​

isBase64()​

isBefore()​

isBIC()​

isBoolean()​

isBtcAddress()​

isByteLength()​

isCreditCard()​

isCurrency()​

isDataURI()​

isDate()​

isDecimal()​

isDivisibleBy()​

isEAN()​

isEmail()​

isEmpty()​

isEthereumAddress()​

isFQDN()​

isFloat()​

isFullWidth()​

isHalfWidth()​

isHash()​

isHexColor()​

isHexadecimal()​

isHSL()​

isIBAN()​

isIdentityCard()​

isIMEI()​

isIP()​

isIPRange()​

isISBN()​

isISSN()​

isISIN()​

isISO6391()​

isISO8601()​

isISO31661Alpha2()​

isISO31661Alpha3()​

isISO4217()​

isISRC()​

isIn()​

isInt()​

isJSON()​

isJWT()​

isLatLong()​

isLength()​

isLicensePlate()​

isLocale()​

isLowercase()​

isLuhnNumber()​

isMagnetURI()​

isMACAddress()​

isMD5()​

isMimeType()​

isMobilePhone()​

isMongoId()​

isMultibyte()​

isNumeric()​

isOctal()​

isPassportNumber()​

isPort()​

isPostalCode()​

isRgbColor()​

isRFC3339()​

isSemVer()​

`ValidationChain`

Built-in validators

`.custom()`

`.exists()`

`.isArray()`

`.isObject()`

`.isString()`

`.notEmpty()`

Standard validators

`contains()`

`equals()`

`isAfter()`

`isAlpha()`

`isAlphanumeric()`

`isAscii()`

`isBase32()`

`isBase58()`

`isBase64()`

`isBefore()`

`isBIC()`

`isBoolean()`

`isBtcAddress()`

`isByteLength()`

`isCreditCard()`

`isCurrency()`

`isDataURI()`

`isDate()`

`isDecimal()`

`isDivisibleBy()`

`isEAN()`

`isEmail()`

`isEmpty()`

`isEthereumAddress()`

`isFQDN()`

`isFloat()`

`isFullWidth()`

`isHalfWidth()`

`isHash()`

`isHexColor()`

`isHexadecimal()`

`isHSL()`

`isIBAN()`

`isIdentityCard()`

`isIMEI()`

`isIP()`

`isIPRange()`

`isISBN()`

`isISSN()`

`isISIN()`

`isISO6391()`

`isISO8601()`

`isISO31661Alpha2()`

`isISO31661Alpha3()`

`isISO4217()`

`isISRC()`

`isIn()`

`isInt()`

`isJSON()`

`isJWT()`

`isLatLong()`

`isLength()`

`isLicensePlate()`

`isLocale()`

`isLowercase()`

`isLuhnNumber()`

`isMagnetURI()`

`isMACAddress()`

`isMD5()`

`isMimeType()`

`isMobilePhone()`

`isMongoId()`

`isMultibyte()`

`isNumeric()`

`isOctal()`

`isPassportNumber()`

`isPort()`

`isPostalCode()`

`isRgbColor()`

`isRFC3339()`

`isSemVer()`