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I have a custom module in Drupal 7 where I am caching data from REST calls using drupal_static() and cache_set().

function _mymodule_call() {
  $data = &drupal_static(__FUNCTION__);
  if ( ! isset($data) ) {
    if ($cache = cache_get(__FUNCTION__)) {
      $data = $cache->data;
    }
    else {
      $data = my_api_call();

      if ( is_object($lists) ) {
        // cache for one hour
        cache_set(__FUNCTION__, $data, 'cache', time() + 3600);
      }
    }
  }
  return $data;
}

I want to make an admin feature where we can specifically clear these cached values. I suppose the cache key would be _mymodule_call. How do I clear them from the cache?

1
4

The Drupal way is to have a $reset parameter to your function. It would look something like:

function _mymodule_call($reset = FALSE) {
  if ($reset) {
    // do stuff
  }
  // ...
}

node_load() is probably the best example of this.

In your specific case, you can pass the $reset parameter to drupal_static() or explicitly call drupal_static_reset(). For the cache backend, you need to think whether you want to just rework the logic and just do the cache_set() or explicitly call cache_clear_all($cid) (my guess is the former).

And remember, that drupal_static() is only effective when you need the value multiple times during the same request. This does not persist between page loads (or any other HTTP request that get handled by Drupal).

2
  • cache_clear_all($cid) -- in my case, would that be cache_clear_all('_mymodule_call')?
    – user1359
    Dec 28 '16 at 1:41
  • @user1359 Looks like it would be cache_set(__FUNCTION__, 'cache'); the $bin needs to be specified when you use the $cid. Check out the API page.
    – mpdonadio
    Dec 28 '16 at 4:40
1

I made a test script, and it turns out that in my code above, _mymodule_call is the $cid, because I created my cache in the _mymodule_call function like so: cache_set(__FUNCTION__, $data, 'cache', time() + 3600);.

Thanks to mpdonadio for noting that you have to specify the $bin argument when you use cache_clear_all(). In my case, since I wasn't specifying it in cache_set(), it defaults to 'cache'.

Here's my script:

$> cat cache_test.php
<?php
// set the cache
cache_set('test_key', 'hello there ' . mt_rand(), 'cache');
$data = cache_get('test_key');
// display it
print_r($data);
// clear it
cache_clear_all('test_key', 'cache');
// retrieve it (should be empty)
$data = cache_get('test_key');
// display the emptied(?) cache
var_dump($data);
print_r($data);

And here's its output:

$> drush scr cache_test.php
stdClass Object
(
    [cid] => test_key
    [data] => hello there 1718114879
    [created] => 1482938803
    [expire] => 0
    [serialized] => 0
)
bool(false)

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