express-validator

An express.js middleware for node-validator.

This is basically a copy of a gist by node-validator author chriso.

Installation

npm install express-validator

Usage

var util = require('util'),
    express = require('express'),
    expressValidator = require('express-validator'),
    app = express.createServer();

app.use(express.bodyParser());
app.use(expressValidator([options]));

app.post('/:urlparam', function(req, res) {

  // checkBody only checks req.body; none of the other req parameters
  req.checkBody('postparam', 'Invalid postparam').notEmpty().isInt();
  req.assert('getparam', 'Invalid getparam').isInt();
  req.assert('urlparam', 'Invalid urlparam').isAlpha();

  req.sanitize('postparam').toBoolean();

  var errors = req.validationErrors();
  if (errors) {
    res.send('There have been validation errors: ' + util.inspect(errors), 400);
    return;
  }
  res.json({
    urlparam: req.param('urlparam'),
    getparam: req.param('getparam'),
    postparam: req.param('postparam')
  });
});

app.listen(8888);

Which will result in:

$ curl -d 'postparam=1' http://localhost:8888/test?getparam=1
{"urlparam":"test","getparam":"1","postparam":true}

$ 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} ]

Middleware Options

####errorFormatter function(param,msg,value)

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.
app.use(expressValidator({
  errorFormatter: function(param, msg, value) {
      var namespace = param.split('.')
      , root    = namespace.shift()
      , formParam = root;

    while(namespace.length) {
      formParam += '[' + namespace.shift() + ']';
    }
    return {
      param : formParam,
      msg   : msg,
      value : value
    };
  }
}));

Validation errors

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();
var mappedErrors = req.validationErrors(true);

errors:

[
  {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>"}
]

mappedErrors:

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

Nested input data

Example:

<input name="user[fields][email]" />

Provide an array instead of a string:

req.assert(['user', 'fields', 'email'], 'valid email required').isEmail();
var errors = req.validationErrors();
console.log(errors);

Output:

[
  {
    param: "user_fields_email",
    msg: "valid email required",
    value: "<received input>"
  }
]

Alternatively you can use dot-notation to specify nested fields to be checked:

req.assert(['user', 'fields', 'email'], 'valid email required').isEmail();

Regex routes

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();

Extending

You can extend the Validator and Filter objects to add custom validation and sanitization method.

Custom validation which always fails. Useful for debugging or for adding messages manually when doing complex validation:

var expressValidator = require('express-validator');

expressValidator.Validator.prototype.fail = function() {
  //You could validate against this.str, instead of just erroring out.

  this.error(this.msg);
  return this;
};

Custom sanitization which lower-cases the string:

expressValidator.Filter.prototype.toLowerCase = function(){
  this.modify(this.str.toLowerCase());
  return this.str;
};

Changelog

v0.4.1

Update this readme

v0.4.0

Added req.checkBody() (@zero21xxx).
Upgraded validator dependency to 1.1.3

v0.3.0

req.validationErrors() now returns null instead of false if there are no errors.

v0.2.4

Support for regex routes (@Cecchi)

v0.2.3

Fix checkHeader() (@pimguilherme)

v0.2.2

Add dot-notation for nested input (@sharonjl)
Add validate() alias for check()

v0.2.1

Fix chaining validators (@rapee)

v0.2.0

Added validationErrors() method (by @orfaust)
Added support for nested form fields (by @orfaust)
Added test cases

v0.1.3

Readme update

v0.1.2

Expose Filter and Validator instances to allow adding custom methods

v0.1.1

Use req.param() method to get parameter values instead of accessing req.params directly.
Remove req.mixinParams() method.

JedWatson/express-validator