Express middleware for the validator module.


An express.js middleware for node-validator.

npm install express-validator
var util = require('util'),
    express = require('express'),
    expressValidator = require('express-validator'),
    app = express.createServer();
app.use(expressValidator([options])); // this line must be immediately after express.bodyParser()!'/:urlparam', function(reqres) {
  // checkBody only checks req.body; none of the other req parameters 
  // Similarly checkParams only checks in req.params (URL params) and 
  // checkQuery only checks req.query (GET params). 
  req.checkBody('postparam', 'Invalid postparam').notEmpty().isInt();
  req.checkParams('urlparam', 'Invalid urlparam').isAlpha();
  req.checkQuery('getparam', 'Invalid getparam').isInt();
  // OR assert can be used to check on all 3 types of params. 
  // req.assert('postparam', 'Invalid postparam').notEmpty().isInt(); 
  // req.assert('urlparam', 'Invalid urlparam').isAlpha(); 
  // req.assert('getparam', 'Invalid getparam').isInt(); 
  // as with validation these will only validate the corresponding 
  // request object 
  // OR find the relevent param in all areas 
  var errors = req.validationErrors();
  if (errors) {
    res.send('There have been validation errors: ' + util.inspect(errors), 400);
    urlparam: req.params.urlparam,
    getparam: req.params.getparam,
    postparam: req.params.postparam

Which will result in:

$ curl -d 'postparam=1' http://localhost:8888/test?getparam=1
$ curl -d 'postparam=1' http://localhost:8888/t1est?getparam=1
There have been validation errors: [
  { param: 'urlparam', msg: 'Invalid urlparam', value: 't1est' } ]
$ curl -d 'postparam=1' http://localhost:8888/t1est?getparam=1ab
There have been validation errors: [
  { param: 'getparam', msg: 'Invalid getparam', value: '1ab' },
  { param: 'urlparam', msg: 'Invalid urlparam', value: 't1est' } ]
$ curl http://localhost:8888/test?getparam=1&postparam=1
There have been validation errors: [
  { param: 'postparam', msg: 'Invalid postparam', value: undefined} ]


The errorFormatter option can be used to specify a function that can be used to format the objects that populate the error array that is returned in req.validationErrors(). It should return an Object that has param, msg, and value keys defined.

// In this example, the formParam value is going to get morphed into form body format useful for printing. 
  errorFormatterfunction(parammsgvalue) {
      var namespace = param.split('.')
      , root    = namespace.shift()
      , formParam = root;
    while(namespace.length) {
      formParam += '[' + namespace.shift() + ']';
    return {
      param : formParam,
      msg   : msg,
      value : value

{ "validatorName": function(value, [additional arguments]), ... }

The customValidators option can be used to add additional validation methods as needed. This option should be an Object defining the validator names and associated validation functions.

Define your custom validators:

 customValidators: {
    isArrayfunction(value) {
        return Array.isArray(value);
    gtefunction(paramnum) {
        return param >= num;

Use them with their validator name:

req.checkBody('users', 'Users must be an array').isArray();
req.checkQuery('time', 'Time must be an integer great than or equal to 5').isInt().gte(5)

{ "sanitizerName": function(value, [additional arguments]), ... }

The customSanitizers option can be used to add additional sanitizers methods as needed. This option should be an Object defining the sanitizer names and associated functions.

Define your custom sanitizers:

 customSanitizers: {
    toSanitizeSomehowfunction(value) {
        var newValue = value;//some operations 
        return newValue;

Use them with their sanitizer name:

   req.check('testparam', 'Error Message').notEmpty().isInt();
   req.check('testparam.child', 'Error Message').isInt(); // find nested params 
   req.check(['testparam', 'child'], 'Error Message').isInt(); // find nested params 

Starts the validation of the specifed parameter, will look for the parameter in req in the order params, query, body, then validate, you can use 'dot-notation' or an array to access nested values.

If a validator takes in params, you would call it like req.assert('reqParam').contains('thisString');.

Validators are appended and can be chained. See chriso/validator.js for available validators, or add your own.

Alias for req.check().

Alias for req.check().

Same as req.check(), but only looks in req.body.

Same as req.check(), but only looks in req.query.

Same as req.check(), but only looks in req.params.

Only checks req.headers. This method is not covered by the general req.check().

If you need to perform asynchronous validation, for example checking a database if a username has been taken already, your custom validator can return a promise.

You MUST use asyncValidationErrors which returns a promise to check for errors, otherwise the validator promises won't be resolved.

asyncValidationErrors will also return any regular synchronous validation errors.

 customValidators: {
   isUsernameAvailablefunction(username) {
     return new Promise(function(resolvereject) {
req.check('username', 'Username Taken').isUsernameAvailable();
req.asyncValidationErrors().catch(function(errors) {

Alternatively you can define all your validations at once using a simple schema. This also enables per-validator error messages. Schema validation will be used if you pass an object to any of the validator methods.

 'email': {
    notEmpty: true,
    isEmail: {
      errorMessage: 'Invalid Email'
  'password': {
    notEmpty: true,
    match: {
      options: ['example', 'i'] // pass options to the validator with the options property as an array 
      // options: ['/example/i'] // match also accepts the full expression in the first parameter 
    errorMessage: 'Invalid Password' // Error message for the parameter 
  'name.first': { // 
    optional: true, // won't validate if field is empty 
    isLength: {
      options: [{ min: 2, max: 10 }],
      errorMessage: 'Must be between 2 and 10 chars long' // Error message for the validator, takes precedent over parameter message 
    errorMessage: 'Invalid First Name'

You have two choices on how to get the validation errors:

req.assert('email', 'required').notEmpty();
req.assert('email', 'valid email required').isEmail();
req.assert('password', '6 to 20 characters required').len(6, 20);
var errors = req.validationErrors(); // Or req.asyncValidationErrors(); 
var mappedErrors = req.validationErrors(true); // Or req.asyncValidationErrors(true); 


  {param: "email", msg: "required", value: "<received input>"},
  {param: "email", msg: "valid email required", value: "<received input>"},
  {param: "password", msg: "6 to 20 characters required", value: "<received input>"}


  email: {
    param: "email",
    msg: "valid email required",
    value: "<received input>"
  password: {
    param: "password",
    msg: "6 to 20 characters required",
    value: "<received input>"

Note: Using mappedErrors will only provide the last error per param in the chain of validation errors.

You can provide an error message for a single validation with .withMessage(). This can be chained with the rest of your validation, and if you don't use it for one of the validations then it will fall back to the default.

req.assert('email', 'Invalid email')
    .notEmpty().withMessage('Email is required')
var errors = req.validationErrors();


  {param: 'email', msg: 'Email is required', value: '<received input>'}
  {param: 'email', msg: 'Invalid Email', value: '<received input>'}

You can use the optional() method to skip validation. By default, it only skips validation if the key does not exist on the request object. If you want to skip validation based on the property being falsy (null, undefined, etc), you can pass in { checkFalsy: true }.

//if there is no error, is either undefined or a valid mail. 
req.body.comment = 'a <span>comment</span>';
req.body.username = '   a user    ';
req.sanitize('comment').escape(); // returns 'a &lt;span&gt;comment&lt;/span&gt;' 
req.sanitize('username').trim(); // returns 'a user' 
console.log(req.body.comment); // 'a &lt;span&gt;comment&lt;/span&gt;' 
console.log(req.body.username); // 'a user' 

Sanitizes the specified parameter (using 'dot-notation' or array), the parameter will be updated to the sanitized result. Cannot be chained, and will return the result. See chriso/validator.js for available sanitizers, or add your own.

If a sanitizer takes in params, you would call it like req.sanitize('reqParam').whitelist(['a', 'b', 'c']);.

If the parameter is present in multiple places with the same name e.g. req.params.comment & req.query.comment, they will all be sanitized.

Alias for req.sanitize().

Same as req.sanitize(), but only looks in req.body.

Same as req.sanitize(), but only looks in req.query.

Same as req.sanitize(), but only looks in req.params.

Only sanitizes req.headers. This method is not covered by the general req.sanitize().

Express allows you to define regex routes like:

app.get(/\/test(\d+)/, function() {});

You can validate the extracted matches like this:

req.assert(0, 'Not a three-digit integer.').len(3, 3).isInt();


  • Christoph Tavan - Wrap the gist in an npm package
  • @orfaust - Add validationErrors() and nested field support
  • @zero21xxx - Added checkBody function

Copyright (c) 2010 Chris O'Hara, MIT License