I'm developing an upgrade to an extension and when this version is installed it's going to need to update the database.

The module extension has been made with civix and I notice there's a CRM_XXX_Upgrader_Base class that looks useful but I can't figure out where I'd put the code I need to run.

Are there any good examples of extension upgrade hooks that I could learn from?

I've looked at a couple of popular extensions, but they don't seem to have used/needed them, so I'm stabbing in the dark a bit.

1 Answer 1


Here is an example of one I have used:

 public function upgrade_1002() {
    $this->ctx->log->info('Applying update 1002 (add country)id to civicrm_project table and renaming manager_id in civicrm_programme table)');
    if (CRM_Core_DAO::checkTableExists('civicrm_project')) {
      if (!CRM_Core_DAO::checkFieldExists('civicrm_project', 'country_id')) {
        CRM_Core_DAO::executeQuery('ALTER TABLE civicrm_project ADD COLUMN country_id INT(11) DEFAULT NULL');
      if (CRM_Core_DAO::checkFieldExists('civicrm_programme' , 'contact_id_manager')) {
        CRM_Core_DAO::executeQuery('ALTER TABLE civicrm_programme CHANGE contact_id_manager manager_id INT(11)');
    return TRUE;

Does this explain it a little? And obviously you also have to make sure your install query is fixed as this will be used when installing, not the upgrades.

And another one with the sql in a separate file:

   * Upgrade 1003 - add table civicrm_case_project
  public function upgrade_1003() {
    $this->ctx->log->info('Applying update 1003 (create civicrm_case_project table');
    if (!CRM_Core_DAO::checkTableExists('civicrm_case_project')) {
    return TRUE;
  • Thanks Eric, where do those upgrade_xxxx functions sit in an extension? How does CiviCRM know they need doing for a given extension? And finally, when you say about install/upgrade: I think you're saying upgrade_xxx functions are not run on install (so the install functions need to be up-to-date), is that right? Apr 29, 2016 at 14:23
  • If you do civix generate:upgrader the appropriate classes will be created for you, the function sit in the CRM/<your namespace>/Upgrader class. And yes, the upgrade functions do not run on install Apr 29, 2016 at 15:20

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