StringField::cast

public function cast($value)
{
	if ($this->is_nullable && $value === null)
	{
		return $value;
	}

	if ($value instanceof SqlExpression)
	{
		return $value;
	}

	$value = (string) $value;

	if ($this->size !== null)
	{
		$value = mb_substr($value, 0, $this->size);
	}

	return $value;
}