ExpressionEngine® 3 User Guide

Legacy Documentation

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Validation Service

Simple Example

Data validation is essential in all programming to ensure safety and correctness of all programs. The Validation service simplifies this task with a concise and extensible API.

$rules = array(
  'username' => 'required|minLength[5]',
  'password' => 'required|minLength[5]'

$result = ee('Validation')->make($rules)->validate($_POST);

if ($result->isValid())
  // yay

// no :(

Defining Rules

Which rules to apply is defined in a string of pipe delimited rule names. The rules are processed from left to right:


Some rules may also take parameters. These are added in braces after the rule name:

"required|enum[blue,red,yellow]" // only allow these three color names

Required Fields

The required rule is used to ensure that fields are set and not blank. A field is considered blank if it only contains whitespace.

If no required rule is encountered then a blank field is considered valid regardless of the other rules:

"numeric|alpha" // despite conflicting rules, a blank field will pass

This means that you will usually want to use required at the beginning of the rule string. The exception being conditional rules, which are covered later.

Conditional Rules

There are times where you only want to apply validation if a certain value has been set. The whenPresent rule allows you to do this:

$rules = array(
  'name' => 'whenPresent|minLength[45]'

A more complex case of this is when certain fields rely on the presence of other fields. A common case for this are checkboxes that enable a functionality. For example, a checkbox to subscribe to an email newsletter may require an email address field that is otherwise optional. The whenPresent rule accepts a list of fields that must all be present for the rules to be applied:

$rules = array(
  'email' => 'whenPresent[newsletter]|required|email'

Custom Rules

ExpressionEngine allows you to create one-off validation rules on any validator object. This is done by calling the defineRule method:

$validator = ee('Validation')->make();

$validator->defineRule('impossible', function($key, $value, $parameters)
  return ($value == 5 && $value == 6);

  'age' => 'required|impossible'

$result = $validator->validate($data);

Custom Conditional Rules

Custom conditional rules can be created by calling skip() on the ValidationRule object. This can be useful, for example, if you need to conditionally validate a field based on the value of another field:

use EllisLab\ExpressionEngine\Service\Validation\Validator;

$data = $_POST;

$validator->defineRule('whenNotifyTypeIs', function($key, $value, $parameters, $rule) use ($data)
  return ($data['notify-type'] == $parameters[0]) ? TRUE : $rule->skip();

  'notify-type' => 'required|enum[email,sms]',
  'email' => 'whenNotifyTypeIs[email]|required|email',
  'sms' => 'whenNotifyTypeIs[sms]|required|regex[/^\d{3}-\d{3}-\d{4}$/]',

Checking a Single Rule

check($rule, $value)

Occasionally, you might need to check whether a value passes a validation rule, you can do that using the check() method:

$valid = ee('Validation')->check('uniqueEmail', '');
  • $rule (string) – The rule to check, see Built-in Rules
  • $value (string) – The value to check

TRUE if the $value is valid

Return type:


Built-in Rules

Rule name Description Example
alpha Any alphabetical character alpha
alphaDash Alpha plus dashes and underscores alphaDash
alphaNumeric Alpha plus numbers alphaNumeric
boolean Must be of boolean type boolean
email Email addresses email
enum Any in a given list enum[blue, red, pink]
exactLength Input must have exactly n characters exactLength[4]
fileExists File or path must exist fileExists
greaterThan Value greater than x greaterThan[5]
hexColor A three or six-character hex code without a pound sign hexColor
integer Must be an integer integer
ipAddress Ip address. Optional parameters: ipv4, ipv6, public ipAddress
isNatural Natural number isNatural
isNaturalNoZero Natural number except zeros isNaturalNoZero
lessThan Value less than x lessThan[5]
limitHtml Limits the kind of HTML tags that can be present in a string limitHtml[a,b,i,span]
maxLength No more than n characters maxLength[5]
minLength No fewer than n characters minLength[8]
noHtml Must not contain HTML noHtml
numeric Any number, including decimals numeric
regex Match a regular expression regex[/^exp.*?ine$/]
required Must not be blank. See Required Fields required
uniqueEmail Must be a unique email. Gmail addresses strip . before checking for uniqueness uniqueEmail
url Must be a valid URL url
validBase64 Base64 character set only validBase64
whenPresent Only validate if field was sent. See Conditional Rules whenPresent
writeable File or path must be writeable writeable
xss Must not contain content that looks like XSS (Cross Site Scripting) xss

Handling Results

Handling validation results can be as fine grained as you need it to be. A call to validate() will return a result object:

$result = $validator->validate($data);

Passed? Failed.

The most basic result check is to see if validation passed or failed. This is done with isValid() and isNotValid():

$result->isValid(); // true | false
$result->isNotValid(); // false | true

Checking Individual Fields

To check if an individual field failed validation, use hasErrors() with the name of the field:

$result->hasErrors('username'); // true | false

Getting Error Messages

Error messages can be read directly from the result object using getAllErrors(). This will return an array that is keyed first by the field name, then by the rule name, and lastly contains the localized failure message:

$errors = $result->getAllErrors(); // $errors['fieldname']['rulename'] = 'Message';

This will return an empty array if nothing has failed.

Individual field errors can either be read by accessing the getAllErrors() result array or by using getErrors with the field name as the first parameter:

// either:
$errors = $result->getAllErrors();
$username_errors = $errors['username'];

// or better:
$username_errors = $result->getErrors('username');

The latter will return an empty array if there were no errors.