`getMetadatas` returns `false`

[convenient]

Hello

I have been trying to debug something using getMetadata but no matter what I do it seems to always return false.

Can you see that I am doing anything wrong here?

Test script

1. Save to cache
2. Read from cache, to verify save worked
3. Try and get metadatas expect to see tags and lifetime, seen nothing

<?php
use Magento\Framework\App\Bootstrap;
require __DIR__ . '/app/bootstrap.php';

$bootstrap = Bootstrap::create(BP, $_SERVER);
$obj = $bootstrap->getObjectManager();

/** @var \Magento\Framework\App\CacheInterface $cache */
$cache = $obj->get(\Magento\Framework\App\CacheInterface::class);
/** @var \Magento\Framework\Cache\Core $lowLevelCache */
$lowLevelCache = $cache->getFrontend()->getLowLevelFrontend();

$key = 'SomeSillyKey';

$result = $cache->save('cache entry value ' . time(), $key, ['Fun_Tags', 'Here'], 123);
echo "save result: " . var_export($result, true) . PHP_EOL;

$readResult = $cache->load($key);
echo "read result: " . $readResult . PHP_EOL;

/** @var Cm_Cache_Backend_Redis $backend */
$backend = $lowLevelCache->getBackend();
echo "backend class: " . get_class($backend) . PHP_EOL;

echo "metadatas result from lowlevelcache: " . var_export($lowLevelCache->getMetadatas($key), true) . PHP_EOL;
echo "metadatas result from backend: " . var_export($backend->getMetadatas($key), true) . PHP_EOL;

Output

save result: true
read result: cache entry value 1668692479
backend class: Cm_Cache_Backend_Redis
metadatas result from lowlevelcache: false
metadatas result from backend: false

[convenient]

I do apologise, seems i needed to strtoupper the key 🤔

<?php
use Magento\Framework\App\Bootstrap;
require __DIR__ . '/app/bootstrap.php';

$bootstrap = Bootstrap::create(BP, $_SERVER);
$obj = $bootstrap->getObjectManager();

/** @var \Magento\Framework\App\CacheInterface $cache */
$cache = $obj->get(\Magento\Framework\App\CacheInterface::class);
/** @var \Magento\Framework\Cache\Core $lowLevelCache */
$lowLevelCache = $cache->getFrontend()->getLowLevelFrontend();

$key = strtoupper('SomeSillyKey');

$result = $cache->save('cache entry value ' . time(), $key, ['Fun_Tags', 'Here'], 123);
echo "save result: " . var_export($result, true) . PHP_EOL;

$readResult = $cache->load($key);
echo "read result: " . $readResult . PHP_EOL;

/** @var Cm_Cache_Backend_Redis $backend */
$backend = $lowLevelCache->getBackend();
echo "backend class: " . get_class($backend) . PHP_EOL;

echo "metadatas result from lowlevelcache: " . var_export($lowLevelCache->getMetadatas($key), true) . PHP_EOL;
echo "metadatas result from backend: " . var_export($backend->getMetadatas($key), true) . PHP_EOL;

save result: true
read result: cache entry value 1668695167
backend class: Cm_Cache_Backend_Redis
metadatas result from lowlevelcache: array (
  'expire' => 1668695290,
  'tags' => 
  array (
    0 => 'd1e_FUN_TAGS',
    1 => 'd1e_HERE',
    2 => 'd1e_MAGE',
  ),
  'mtime' => '1668695167',
)
metadatas result from backend: false

[colinmollenhour]

I think the Magento wrapper uppercases the keys so when you bypass the Magento wrapper you have to uppercase the keys yourself.