Reference

Guide

Validators

Validators are registered with the validators extension. The validators extension accepts an array of validators where the key is the name of the validator and the value a callback function that receives the value as parameter and returns a boolean.

/site/plugins/your-plugin/index.php
Kirby::plugin('your/plugin', [
  'validators' => [
    'isGreen' => function ($value) {
      return V::in($value, ['green','lightgreen', 'darkgreen', 'mediumgreen'];
    }
  ]
]);

In your templates, you can now check if the value is in the given array of green values:

/site/templates/default.php
$input = 'lightgreen';
if(V::isGreen($input)) {
  echo 'Yay, valid!';
} else {
  echo 'Oh no, not valid';
}