Problem with Workbench Moderation and Metatag caching

Odd. I wonder would #2420489: Restructure entity caching so it can be cleared more easily help?

Clearly, though, it needs to hook into WM and clear the cache on a state change.

Just to confirm it - what version of Workbench Moderation are you using?

Hey guys, here's a solution as a custom module hook - a temporary workaround for me that takes the approach
of #1.
I could easily roll this into a patch for Metatag, but I wonder if anyone has any input regarding the
cache key being used to wipe cache entries - I'm not intimately familiar with all of the components
of the cid used in cache_metatag. This code seems appropriate to me, but maybe there's a way some keys
are built that makes this either too heavy handed or perhaps misses a scenario.

/**
 * Implements hook_workbench_moderation_transition
 */
function custom_workbench_moderation_transition($node, $previous_state, $new_state) {
  // Clear metatag cache for nodes on any state change (see https://www.drupal.org/node/2467587)
  db_query("DELETE FROM {cache_metatag} WHERE cid LIKE :cid", array(':cid' => 'output:node:' . $node-
>nid . '%'));
}

You should use:

metatag_metatags_cache_clear($entity_type, $entity_id);

The other cache thingy is something else, though disabling the output cache would cover up this issue.

Not going to do this for 1.5.

Does this fix the problem?

This patch was posted during the time I wrote a nearly identical version. Interesting timing :)

I applied and tested this patch to a 1.4 installation of metatag and it works as intended.

@beeradb: Thanks for the review!

Committed.