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Version: 5.3.0

Legacy API

The "legacy API" is the same API used by version 3 and older releases of express-validator.

It's based around setting a global middleware in your express app and decorating the request object with new methods.

This API MUST NOT be used by new apps, since it may not receive new updates and can even be removed in a future major version.

Setup​

You must mount the middleware in your app before you get access to the validation/sanitization methods:

const expressValidator = require('express-validator');
app.use(expressValidator(middlewareOptions));

Middleware options​

  • errorFormatter (param, msg, value, location): a function that formats the error objects before returning them to your route handlers.
  • customValidators: an object where you can specify custom validators.
    The key will be the name of the validator, while the value is the validation function, receiving the value and any option.
  • customSanitizers: an object where you can specify custom sanitizers.
    The key will be the name of the sanitizer, while the value is the sanitization function, receiving the value and any option.

Legacy Validation Chain​

The Legacy Validation Chain instances provides further functionality than the one provided by the base Validation Chain objects.
It also differs in that the legacy one is not a middleware per se.

Any custom validator specified in the middleware will be made available in instances of this validation chain.

Additionally, the following validators are also available:

  • .notEmpty(): alias of .isLength({ min: 1 })
  • .len(): alias of .isLength()

req.check(field[, message])​

  • field: the name of a single field to validate against.
  • message (optional): an error message to use when failed validators don't specify a message. Defaults to Invalid value.

    Returns: a legacy validation chain

Creates a validation chain for one field. It may be located in any of the following request objects:

  • req.params
  • req.query
  • req.body
  • req.headers
  • req.cookies

If it's present in more than one location, then only the first one (following the above order) will be validated against.

This function is also aliased as req.assert() and req.validate().

req.checkBody(field[, message])​

Same as req.check(field[, message]), but only checking req.body.

req.checkCookies(field[, message])​

Same as req.check(field[, message]), but only checking req.cookies.

req.checkHeaders(field[, message])​

Same as req.check(field[, message]), but only checking req.headers.

req.checkParams(field[, message])​

Same as req.check(field[, message]), but only checking req.params.

req.checkQuery(field[, message])​

Same as req.check(field[, message]), but only checking req.query.

req.sanitize(field)​

Returns: a sanitizer chain

Creates a sanitizer chain that, when any of the sanitization methods is used, the return value is the sanitized value.
Also, the parameter is sanitized in-place; that is, in the below example, req.body.comment will be updated to the sanitized value.

const comment = req.sanitize('comment').trim();
console.log(comment === req.body.comment);

If the sanitized parameter is present in more than one location (eg req.query.comment and req.body.comment), the will all be sanitized.

This function is also aliased as req.filter().

req.sanitizeBody(field[, message])​

Same as req.sanitize(field[, message]), but only sanitizing req.body.

req.sanitizeCookies(field[, message])​

Same as req.sanitize(field[, message]), but only sanitizing req.cookies.

req.sanitizeHeaders(field[, message])​

Same as req.sanitize(field[, message]), but only sanitizing req.headers.

req.sanitizeParams(field[, message])​

Same as req.sanitize(field[, message]), but only sanitizing req.params.

req.sanitizeQuery(field[, message])​

Same as req.sanitize(field[, message]), but only sanitizing req.query.

req.getValidationResult()​

Returns: a promise for a Validation Result object

Runs all validations and returns a validation result object for the errors gathered, for both sync and async validators.

req.asyncValidationErrors([mapped])​

  • mapped (optional): whether the result must be an object instead of an array. Defaults to false.

    Returns: a promise which will resolve in case all validators passed, or reject with an array of errors or an object of errors (in case mapped argument is true).

Runs all validations and returns the errors gathered for all of them.

req.validationErrors([mapped])​

  • mapped (optional): whether the result must be an object instead of an array. Defaults to false.

    Returns: false if no errors happened, an array of errors or an object of errors (in case mapped argument is true).

Runs all validations and returns the errors gathered only for the completed validators.
This probably means any async validator will not be completed by the time this method responds.

Schema validation​

All req.check methods can do schema validation. The schema syntax is the same as described in Schema Validation.