Enables or installs a given list of modules.

Definitions:

• "Enabling" is the process of activating a module for use by Drupal.
• "Disabling" is the process of deactivating a module.
• "Installing" is the process of enabling it for the first time or after it has been uninstalled.
• "Uninstalling" is the process of removing all traces of a module.

Order of events:

• Gather and add module dependencies to $module_list (if applicable).
• For each module that is being enabled:
  • Install module schema and update system registries and caches.
  • If the module is being enabled for the first time or had been uninstalled, invoke hook_install() and add it to the list of installed modules.
  • Invoke hook_enable().
• Invoke hook_modules_installed().
• Invoke hook_modules_enabled().

Parameters

string[] $module_list: An array of module names.

bool $enable_dependencies: If TRUE, dependencies will automatically be added and enabled in the correct order. This incurs a significant performance cost, so use FALSE if you know $module_list is already complete and in the correct order.

Return value

bool FALSE if one or more dependencies are missing, TRUE otherwise.

See also

hook_install()

hook_enable()

hook_modules_installed()

hook_modules_enabled()

module_disable()

drupal_uninstall_modules()

38 calls to module_enable()

BlockHashTestCase::testBlockRehash in modules/block/block.test

Tests that block rehashing does not write to the database too often.

BlockTestCase::testBlockRehash in modules/block/block.test

Test _block_rehash().

CommentActionsTestCase::testCommentPublishUnpublishHooks in modules/comment/comment.test

Test comment publish and unpublish hooks.

CommentAuthorDeletionTestCase::testAuthorDeletionCommentModuleDisabled in modules/comment/comment.test

Test comment author deletion while the comment module is disabled.

CronRunTestCase::testCronCacheExpiration in modules/system/system.test

Tests that hook_flush_caches() is not invoked on every single cron run.

... See full list

File

includes/module.inc, line 401

Code

function module_enable ($module_list, $enable_dependencies = TRUE) {
 if ($enable_dependencies) {
 // Get all module data so we can find dependencies and sort.
 $module_data = system_rebuild_module_data ();
 // Create an associative array with weights as values.
 $module_list = array_flip (array_values ($module_list));
 // The array is iterated over manually (instead of using a foreach) because
 // modules may be added to the list within the loop and we need to process
 // them.
 while ($module = key ($module_list)) {
 next ($module_list);
 if (!isset($module_data[$module])) {
 // This module is not found in the filesystem, abort.
 return FALSE;
 }
 if ($module_data[$module]->status) {
 // Skip already enabled modules.
 unset($module_list[$module]);
 continue;
 }
 $module_list[$module] = $module_data[$module]->sort;
 // Add dependencies to the list, with a placeholder weight.
 // The new modules will be processed as the while loop continues.
 foreach (array_keys ($module_data[$module]->requires) as $dependency) {
 if (!isset($module_list[$dependency])) {
 $module_list[$dependency] = 0;
 }
 }
 }
 if (!$module_list) {
 // Nothing to do. All modules already enabled.
 return TRUE;
 }
 // Sort the module list by pre-calculated weights.
 arsort ($module_list);
 $module_list = array_keys ($module_list);
 }
 // Required for module installation checks.
 include_once DRUPAL_ROOT  . '/includes/install.inc';
 $modules_installed = array();
 $modules_enabled = array();
 foreach ($module_list as $module) {
 // Only process modules that are not already enabled.
 $existing = db_query ("SELECT status FROM {system} WHERE type = :type AND name = :name", array(
 ':type' => 'module',
 ':name' => $module,
 ))->fetchObject ();
 if ($existing->status == 0) {
 // Load the module's code.
 drupal_load ('module', $module);
 module_load_install ($module);
 // Update the database and module list to reflect the new module. This
 // needs to be done first so that the module's hook implementations,
 // hook_schema() in particular, can be called while it is being
 // installed.
 db_update ('system')->fields (array(
 'status' => 1,
 ))
 ->condition ('type', 'module')
 ->condition ('name', $module)
 ->execute ();
 // Refresh the module list to include it.
 system_list_reset ();
 module_list (TRUE);
 module_implements ('', FALSE, TRUE);
 _system_update_bootstrap_status ();
 // Update the registry to include it.
 registry_update ();
 // Refresh the schema to include it.
 drupal_get_schema (NULL, TRUE);
 // Update the theme registry to include it.
 drupal_theme_rebuild ();
 // Clear entity cache.
 entity_info_cache_clear ();
 // Now install the module if necessary.
 if (drupal_get_installed_schema_version ($module, TRUE) == SCHEMA_UNINSTALLED ) {
 drupal_install_schema ($module);
 // Set the schema version to the number of the last update provided
 // by the module.
 $versions = drupal_get_schema_versions ($module);
 $version = $versions ? max ($versions) : SCHEMA_INSTALLED ;
 // If the module has no current updates, but has some that were
 // previously removed, set the version to the value of
 // hook_update_last_removed().
 if ($last_removed = module_invoke ($module, 'update_last_removed')) {
 $version = max ($version, $last_removed);
 }
 drupal_set_installed_schema_version ($module, $version);
 // Allow the module to perform install tasks.
 module_invoke ($module, 'install');
 // Record the fact that it was installed.
 $modules_installed[] = $module;
 watchdog ('system', '%module module installed.', array(
 '%module' => $module,
 ), WATCHDOG_INFO );
 }
 // Enable the module.
 module_invoke ($module, 'enable');
 // Record the fact that it was enabled.
 $modules_enabled[] = $module;
 watchdog ('system', '%module module enabled.', array(
 '%module' => $module,
 ), WATCHDOG_INFO );
 }
 }
 // If any modules were newly installed, invoke hook_modules_installed().
 if (!empty($modules_installed)) {
 module_invoke_all ('modules_installed', $modules_installed);
 }
 // If any modules were newly enabled, invoke hook_modules_enabled().
 if (!empty($modules_enabled)) {
 module_invoke_all ('modules_enabled', $modules_enabled);
 }
 return TRUE;
}

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