Bug: slash_item() errors when asked for a configuration item which doesn't exist

[Tras2]

PHP Version

8.1

CodeIgniter4 Version

4.1.9

CodeIgniter4 Installation Method

Manual (zip or tar.gz)

Which operating systems have you tested for this bug?

Linux

Which server did you use?

cli-server (PHP built-in webserver)

Database

No response

What happened?

slash_item in Sys\Common errors when the configuration item doesn’t exist, which is contrary to expected outcome as per the documention

Steps to Reproduce

<?php

namespace App\Controllers;

class Home extends BaseController
{
    public function poc()
    {
        # returns the baseURL as expected
        echo slash_item('baseURL');

        # this generates an error - detailed below
        echo slash_item('item_does_not_exist');
    }
}

The error that is displayed is this:-

ErrorException
Undefined property: Config\App::$item_does_not_exist
SYSTEMPATH/Common.php at line 987

980      *
981      * @return string|null The configuration item or NULL if
982      *                     the item doesn't exist
983      */
984     function slash_item(string $item): ?string
985     {
986         $config     = config(App::class);
987         $configItem = $config->{$item};
988 
989         if (! isset($configItem) || empty(trim($configItem))) {
990             return $configItem;
991         }
992 
993         return rtrim($configItem, '/') . '/';
994     }

Expected Output

As per the documentation, the return should be null when a configuration doesn't exist

Anything else?

I've never done a pull request before, but can attempt to do my first one if required

However I have identified what I believe to be the cause of this and here is the updated slash_item code for Common.php

if (! function_exists('slash_item')) {
    // Unlike CI3, this function is placed here because
    // it's not a config, or part of a config.
    /**
     * Fetch a config file item with slash appended (if not empty)
     *
     * @param string $item Config item name
     *
     * @return string|null The configuration item or NULL if
     *                     the item doesn't exist
     */
    function slash_item(string $item): ?string
    {
        $config     = config(App::class);
        
        if (property_exists($config, $item))
        {
            $configItem = $config->{$item};
        }
        
        if (! isset($configItem) || empty(trim($configItem))) {
            return null;
        }

        return rtrim($configItem, '/') . '/';
    }
}

[kenjis]

Thank you for taking time.

You are correct. This is a bug, but for what do you use this function?
I don't see use cases.

[kenjis]

This function is used in HTML helper, so we can't remove.

[Tras2]

I was looking for the quickest/simplest way to display a config item value in a view, and was evaluating this function when I came across the issue.

My use-case has since changed and I no longer use this function, but still thought it a simple bug worth raising

[aletoropov]

I'll take it

[MGatner]

What a strange function. I assume this is some CI3 code that rolled in and hasn't had a pass in a long time. It's also somewhat erroneous, because the empty() check will cause 0 or false values (like $negotiateLocale) to return null. I recommend that we deprecate this function for removal in v5.

@aletoropov Thanks for stepping in!