Checks each property (eg $property_name) of an object for a validatePropertyName($value) function, and runs it. If it's invalid it adds it to an array of invalid properties and returns it.

getInvalidProperties.php

<?php

class SomeClass {

    const FIELD_MISSING = 'Missing';
    const FIELD_INVALID = 'Invalid';

    /**
     * Checks each field for a validate function for each field of the object and runs it
     * Override to change this functionality
     * @param array $attributes
     * @return array
     */
    public function getInvalidProperties() {
 
        $invalidFields = array();
        foreach(get_object_vars($this) as $property => $value) {
            $validateFunction = 'validate'.str_replace(' ', '', ucwords(str_replace('_', ' ', $property)));
            if(method_exists($this, $validateFunction)) {
                if(!$this->$validateFunction($value)) {
                    if($value) {
                        $invalidFields[$property] = static::FIELD_INVALID;
                    }
                    else {
                        $invalidFields[$property] = static::FIELD_MISSING;
                    }
                }
            }
        }
 
        return $invalidFields;
    }
    
}

class Test extends SomeClass {
    $test_value;

    public function validateTestValue($value) {
        $len = strlen($value);
        return $len > 0 && $len < 10;
    }
}

$test = new Test();
$missing = $test->getInvalidProperties();

$test->test_value = 'blahblahblah';
$invalid = $test->getInvalidProperties();