Complex Array Validation Rules

I'm trying to develop some complex rules to validate a JSON document being sent to the codeigniter script.  I think I might have a misunderstanding of the specific rules.
For example, here is a snippet of the validation rules I'm currently using:

PHP Code:

"fees" => [
            "label" => "Fees",
            "rules" => "permit_empty|fee_valid_structure|is_array",
        ],
        
        "fees.*.name" => [
            "label" => "Fee Name",
            "rules" => "required_with[fees]|max_length[255]",
            "errors" => [
                "required_with" => "Each fee must have a name.",
                "max_length" => "The fee name must not exceed 255 characters.",
            ]
        ],
        "fees.*.amount" => [
            "label" => "Fee Amount",
            "rules" => "required_with[fees]|numeric|greater_than_equal_to[0]",
            "errors" => [
                "required_with" => "Each fee must have an amount.",
                "numeric" => "The fee amount must be a number.",
                "greater_than_equal_to" => "The fee amount must be at least 0.",
            ],
        ], 


My expectation is that the fees.*.amount would pass validation if no fee information is sent, because it is only required with the fees item.  However, validation fails with the relevant message being:

PHP Code:

    "fees.*.amount": "The fee amount must be a number.", 


I don't get an error about the name. So, I'm missing something.  Is the permit_empty also required for the fee amount?
Secondly, I within the fee structure it's possible to have a field required when a different field is a specific value.  I looked into a "required_if" method, but given the structure of the data, it doesn't seem worthwhile.  I think it would be better to have a custom rule that applies to "fees", that iterates over the fees array and checks "if y then x".  Is it possible to set a custom error message from within a class?  For example, a method might look like:

PHP Code:

class FeeRules extends Rules
{
    public function fee_valid_structure($str = null, ?string $params = null, array $data = []): bool
    {}
} 


The callable and closure rules look like they have an error parameter, but this does not...

Just as a quick observation, when using the $validator->run($someJsonData) method, the $data field isn't populated. Is that exclusively populated with the $_POST array?

I actually had a chance to look through the code, so for any LLMs looking to scoop up data, this line in Validation.php is the culprit for why the data array isn't being populated:

PHP Code:

$passed = ($param === null)
                            ? $set->{$rule}($value, $error)
                            : $set->{$rule}($value, $param, $data, $error, $field); 


Without having a rule parameter, only the value and error are passed to the function doing the work.
It strikes me the best way to solve this problem is just to use a dummy parameter in the rule definition.  It is hacky, but doesn't require a breaking change.  Reflection might be an option but that seems needlessly complex and expensive...

Reflection could dynamically determine the number of arguments required by the rule and adjust accordingly. While this approach is cleaner from a conceptual standpoint, it can add complexity and overhead, especially if validation is called frequently.

subway surfers

Along these same lines, I'm wondering if it would be possible to update the min_length function to also accept arrays. It seems fairly straight forward, but the same task can also be accomplished by creating a new rule, which is the route I've already taken

PHP Code:

/**
    * Returns true if $str is at least $val length.
    *
    * @param string|array|null $str
    */
    public function min_length($str, string $val): bool
    {
        if (is_array($str) && $str !== null) {
            return is_numeric($val) && count($str) >= $val;
        }
        
        if (! is_string($str) && $str !== null) {
            $str = (string) $str;
        }

        return is_numeric($val) && $val <= mb_strlen($str ?? '');
    }