Let's share custom validation rules

I think it would be beneficial to share custom validation rules. So, I will post some of mine below.

They might not be very universal, but still useful.

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Rule  for validation rule for Lithuanian personal idntification number (not properly localizable, but it is easy to add localization to $error and $error_msg strings)

PHP Code:

/** 
 * Codeigniter 4 validation rule for Lithuanian personal idntification number
 */ 

class CustomRules
{
    public function valid_lt_id($value, ?string &$error = null): bool
    {
        $valid = true;
        $error_msg = '';

        //check length/type
        if ($valid && (strlen($value) !== 11 || !is_numeric($value))) {
            $valid = false;
            $error_msg = 'length not equal to 11 numbers, or not all numbers';
        }

        $digits = str_split($value);

        //check date for validity
        if ($valid) {
            if (in_array($digits[0], [1, 2])) {
                $prefix = '18';
            } elseif (in_array($digits[0], [3, 4])) {
                $prefix = '19';
            } elseif (in_array($digits[0], [5, 6])) {
                $prefix = '20';
            } else {
                $prefix = '21';
            }

            $fullDate = $prefix . substr($value, 1, 6);
            $dateFormat = 'Ymd';

            // Create a DateTime object from the provided date string
            $date = DateTime::createFromFormat($dateFormat, $fullDate);

            // Check if the date is valid and the input format is correct
            $valid = $date && $date->format($dateFormat) === ($fullDate);
            if (!$valid) {
                $error_msg = 'wrong date inside number';
            }
        }

        // check date for not future
        if ($valid) {
            $valid = $fullDate <= date('Ymd');

            if (!$valid) {
                $error_msg = 'date in the future cannot be correct';
            }
        }

        // check control number
        if ($valid) {

            $last = null;
            $s = $digits[0] * 1 + $digits[1] * 2 + $digits[2] * 3
                + $digits[3] * 4 + $digits[4] * 5 + $digits[5] * 6
                + $digits[6] * 7 + $digits[7] * 8 + $digits[8] * 9
                + $digits[9] * 1;

            if (($s % 11) !== 10) {
                $last = $s % 11;
            } else {
                $s = $digits[0] * 3 + $digits[1] * 4 + $digits[2] * 5 
                    + $digits[3] * 6 + $digits[4] * 7 + $digits[5] * 8 
                    + $digits[6] * 9 + $digits[7] * 1 + $digits[8] * 2 
                    + $digits[9] * 3;

                if (($s % 11) !== 10) {
                    $last = $s % 11;
                } else {
                    $last = 0;
                }
            }

            $valid = $digits[10] == $last;
            if (!$valid) {
                $error_msg = 'wrong control number';
            }
        }

        //check if the order number is not zero, should never be
        if ($valid && (string) substr($value, 7, 3) === '000') {
            $valid = false;
            $error_msg = 'wrong registration number';
        }

        if ($valid) {
            return true;
        }
        // $error = lang('myerrors.invalidCode');
        $error = 'Lithuanian Personal Identification Number is not valid: ' 
            . $error_msg;
        return false;
    }
} 


==

Donatas G.

Another validation function checks if the supplied value is unique to a particular user; it presupposes that the user ID in a particular db table is saved in `user_id` field and that the current user id is saved in a session variable `$_SESSION['user_id']`; otherwise it is to be used much like the default `is_unique` validation rule:

PHP Code:

    'name' => [
            'label' => 'Name',
            'rules' => 'required|max_length[100]|is_unique_to_user[clients.name,id,{id}]',
        ], 


This rule presupposes that your language Validation will contain an array key-value pair something like this:

PHP Code:

'is_unique_to_user' => 'Field {field} should have a unique value.', 


so, here is the function:

PHP Code:

    public function is_unique_to_user(?string $str, string $field, array $data): bool
    {
        [$field, $ignoreField, $ignoreValue] = array_pad(
            explode(',', $field),
            3,
            null
        );

        sscanf($field, '%[^.].%[^.]', $table, $field);

        $row = Database::connect($data['DBGroup'] ?? null)
            ->table($table)
            ->select('1')
            ->where('user_id', $_SESSION['user_id'])
            ->where($field, $str)
            ->limit(1);

        if (
            ! empty($ignoreField) && ! empty($ignoreValue)
            && ! preg_match('/^\{(\w+)\}$/', $ignoreValue)
        ) {
            $row = $row->where("{$ignoreField} !=", $ignoreValue);
        }

        return $row->get()->getRow() === null;
    } 


==

Donatas G.