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Syncing tags and other data.

The normal sync process looks at the membership groups and -if configured- interest groups, and does a two-way sync on these. However you can also do a "data sync" by passing the with_data=1 parameter to the Mailchimpsync.fetcfetchandreconcile API call.

A data sync allows you to send data from CiviCRM to Mailchimp, but not the other way; it's 1-way only.

Included with this extension is a tag sync: all CiviCRM tags get added to all members at Mailchimp, with the prefix "CiviCRM:".

So if you have a contact tagged "Volunteer" they'll end up with the tag "CiviCRM: Volunteer" at Mailchimp. Remove the tag in CiviCRM and after the next data sync the tag will be removed at Mailchimp. Remember this is a one-way sync; you're not supposed to add/remove a CiviCRM tag at Mailchimp. (If you do, it will stay as you set it at Mailchimp until the next data sync that needs to include that contact, i.e. until you make a tags change in CiviCRM for that contact. Confusing. Don't do it!)

The data sync only updates the tags registered in CiviCRM. It won't interfere with any other Mailchimp tags that you may have been using.

Syncing other data

You may have your own needs for more data in Mailchimp, e.g. membership end date, or details about the last contribution etc. Or even some other data that that you want to use to update a different tag at Mailchimp.

You can do this by writing your own extension and implementing a few hooks. When the fetchandreconcile action is called with_data, the following hooks are called:

  1. hook_mailchimpsync_data_updates_check_pre This is called first and is an opportunity to do lookups that are cheaper to do en-masse.

  2. hook_mailchimpsync_data_updates_check - called once for every cache entry processed.

  3. hook_mailchimpsync_data_updates_check_post - chance to clean up, if needed.

How to implement the hooks.

These are Symfony hooks, so for example to listen for the first two:

 * Implements hook_civicrm_container
 * We register 2 hooks to copy CiviCRM tags to Mailchimp.
 * @param \Symfony\Component\DependencyInjection\ContainerBuilder $container
function <yourext>_civicrm_container($container) {
            ->addMethodCall('addListener', [
            ->addMethodCall('addListener', [

The pre hook. hook_mailchimpsync_data_updates_check_pre

Please see the code in mailchimpsync.php for the function mailchimpsync__tags_sync_pre which is the implementation of the tags sync. The $event->pre_data array is there for extensions to cache data. The tags sync uses the mc_tags key within that array as a container for the things it needs, you should use something unique to your extension for yours. The tag updates then stores a lookup of registered tags for Contacts, and uses a single SQL query to generate a list of all tags on all relevant contacts.

The main in-loop hook. hook_mailchimpsync_data_updates_check

Please see the code in mailchimpsync.php for the function mailchimpsync__tags_sync which is the implementation of the tags sync.

The $event->pre_data array populated in the previous hook is available, and this hook would be typically implemented by...

  • Unserialize the $event->cache_entry->civicrm_data and work with a unique key within that array, e.g. the tags sync uses mcs_tags.

  • Figure out what the current data is for this contact. The tags sync is gets this from the pre_data made in the first hook.

  • Using the current data and any metadata previously stored, determine if an update is required. The tags sync uses a previous key to store the last value, so it can compare this now. If an update is required...

  • Update the cache entry's status to 'todo' if it would not have normally been included in the sync. (Contacts are only usually included if their groups have changed since the last sync.)

  • Provide data under mailchimp_updates and/or tag_updates under a key in the unserialized civicrm_data. The tag sync will create an array within $data['mcs_tags']['tag_updates'] like

  { name: "CiviCRM: Volunteer", status: "active" },
  { name: "CiviCRM: NGO", status: "inactive" },

Things under tag_updates need to be in the correct Mailchimp API format for the POST lists/<listId>/members/<memberId>/tags call.

Things under mailchimp_updates need to be in the correct Mailchimp API format for the POST/PATCH/PUT lists/<listId>/members/<memberId> call, e.g. { merge_fields: { MYMERGE: 'my data' }}

  • Update $event->needs_saving if the cache entry was changed at all (regardless whether that change requires updates).

The post/cleanup hook hook_mailchimpsync_data_updates_check_post

You might use this for example, to delete a table created in the _pre hook.

Use the Source

As well as reading through the code for the tag sync, you might like to read the docblock comments in CRM_Mailchimpsync_Audience::checkForDataUpdates and CRM_Mailchimpsync_Audience::reconcileExtraData might also be useful reading.

Which contacts are included?

These hooks are called for civicrm_mailchimpsync_cache IDs that are either subscribed at Mailchimp, or already identified as needing an update. Please read the code comments inside the CRM_Mailchimpsync_Audience::reconcileExtraData method which explain how and why this is a superset of those that might need updating.