Violin is an easy to use, highly customisable PHP validator.

2.2.3 2020-06-05 13:46 UTC

This package is auto-updated.

Last update: 2023-03-05 20:12:07 UTC


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Violin is an easy to use, highly customisable PHP validator.

Note: This package is under heavy development and is not recommended for production.


Install using Composer.

    "require": {
        "alexgarrett/violin": "2.*"

Basic usage

use Violin\Violin;

$v = new Violin;

    'name'  => ['billy', 'required'],
    'age'   => [20, 'required|int']

if($v->passes()) {
    echo 'Validation passed, woo!';
} else {
    echo '<pre>', var_dump($v->errors()->all()), '</pre>';

Adding custom rules

Adding custom rules is simple. If the closure returns false, the rule fails.

$v->addRuleMessage('isbanana', 'The {field} field expects "banana", found "{value}" instead.');

$v->addRule('isbanana', function($value, $input, $args) {
    return $value === 'banana';

    'fruit' => ['apple', 'isbanana']

Adding custom error messages

You can add rule messages, or field messages for total flexibility.

Adding a rule message

$v->addRuleMessage('required', 'You better fill in the {field} field, or else.');

Adding rule messages in bulk

    'required' => 'You better fill in the {field} field, or else.',
    'int'      => 'The {field} needs to be an integer, but I found {value}.',

Adding a field message

Any field messages you add are used before any default or custom rule messages.

$v->addFieldMessage('username', 'required', 'You need to enter a username to sign up.');

Adding field messages in bulk

    'username' => [
        'required' => 'You need to enter a username to sign up.'
    'age' => [
        'required' => 'I need your age.',
        'int'      => 'Your age needs to be an integer.',

Using Field Aliases

Field Aliases helps you format any error messages without showing weird form names or the need to create a custom error.

    'username_box|Username' => ['' => 'required']

// Error output: "Username is required."


Violin allows you to attach callbacks to be run before or after any validation. This might be useful if you need to do some further validation, or maybe raise an event. You can add as many before and after callbacks as you want, and you can also use the current Violin instance within them.


$v->before(function($violin) {
    // This will happen before the validation..
$v->after(function($violin) {
    // This will happen after the validation..

Extending Violin

You can extend the Violin class to add custom rules, rule messages and field messages. This way, you can keep a tidy class to handle custom validation if you have any dependencies, like a database connection or language files.

class MyValidator extends Violin
    protected $db;

    public function __construct(PDO $db)
        $this->db = $db;

        // Add rule message for custom rule method.
        $this->addRuleMessage('uniqueUsername', 'That username is taken.');

    // Custom rule method for checking a unique username in our database.
    // Just prepend custom rules with validate_
    public function validate_uniqueUsername($value, $input, $args)
        $user = $this->db->prepare("
            SELECT count(*) as count
            FROM users
            WHERE username = :username

        $user->execute(['username' => $value]);

        if($user->fetchObject()->count) {
            return false; // Username exists, so return false.

        return true;

// A database connection.
$db = new PDO('mysql:host=;dbname=website', 'root', 'root');

// Instantiate your custom class with dependencies.
$v = new MyValidator($db);

    'username' => ['billy', 'required|uniqueUsername']


This list of rules are in progress. Of course, you can always contribute to the project if you'd like to add more to the base ruleset.


If the value is alphanumeric.


If the value is alphanumeric. Dashes and underscores are permitted.


If the value is alphabetic letters only.


If the value is an array.

between(int, int)

Checks if the value is within the intervals defined. This check is inclusive, so 5 is between 5 and 10.


If the value is a boolean.


If the value is a valid email.


If the value is an integer, including numbers within strings. 1 and '1' are both classed as integers.


If the value is a number, including numbers within strings.

Numeric strings consist of optional sign, any number of digits, optional decimal part and optional exponential part. Thus +0123.45e6 is a valid numeric value. Hexadecimal (e.g. 0xf4c3b00c), Binary (e.g. 0b10100111001), Octal (e.g. 0777) notation is allowed too but only without sign, decimal and exponential part.


If the value is a valid IP address.

min(int, [number])

Check if string length is greater than or equal to given int. To check the size of a number, pass the optional number option.

    'username' => ['billy', 'required|min(3)|max(20)'],
    'age' => ['20', 'required|min(18, number)|max(100, number)']

max(int, [number])

Check if string length is less than or equal to given int. To check the size of a number, pass the optional number option.


If the value is present.


If the value is formatted as a valid URL.


Checks if one given input matches the other. For example, checking if password matches password_confirm.


If the given input is a valid date.

You can validate human readable dates like '25th October 1961' and instances of DateTime. For example:

$twoDaysAgo = new DateTime('2 days ago');
$date = $twoDaysAgo->format('d M Y');

    'date' => [$date, 'required|date']


If a field has been 'checked' or not, meaning it contains one of the following values: 'yes', 'on', '1', 1, true, or 'true'. This can be used for determining if an HTML checkbox has been checked.


If the given input has a match for the regular expression given.


Please file issues under GitHub, or submit a pull request if you'd like to directly contribute.

Running tests

Tests are run with phpunit. Run ./vendor/bin/phpunit to run tests.