drupal/core/modules/system/system.api.php

<?php

/**
 * @file
 * Hooks provided by Drupal core and the System module.
 */

use Drupal\Component\Utility\SafeMarkup;
use Drupal\Core\Mail\MailFormatHelper;
use Drupal\Core\Url;
use Drupal\taxonomy\Entity\Vocabulary;

/**
 * @addtogroup hooks
 * @{
 */

/**
 * Flush all persistent and static caches.
 *
 * This hook asks your module to clear all of its static caches,
 * in order to ensure a clean environment for subsequently
 * invoked data rebuilds.
 *
 * Do NOT use this hook for rebuilding information. Only use it to flush custom
 * caches.
 *
 * Static caches using drupal_static() do not need to be reset manually.
 * However, all other static variables that do not use drupal_static() must be
 * manually reset.
 *
 * This hook is invoked by drupal_flush_all_caches(). It runs before module data
 * is updated and before hook_rebuild().
 *
 * @see drupal_flush_all_caches()
 * @see hook_rebuild()
 */
function hook_cache_flush() {
  if (defined('MAINTENANCE_MODE') && MAINTENANCE_MODE == 'update') {
    _update_cache_clear();
  }
}

/**
 * Rebuild data based upon refreshed caches.
 *
 * This hook allows your module to rebuild its data based on the latest/current
 * module data. It runs after hook_cache_flush() and after all module data has
 * been updated.
 *
 * This hook is only invoked after the system has been completely cleared;
 * i.e., all previously cached data is known to be gone and every API in the
 * system is known to return current information, so your module can safely rely
 * on all available data to rebuild its own.
 *
 * @see hook_cache_flush()
 * @see drupal_flush_all_caches()
 */
function hook_rebuild() {
  $themes = \Drupal::service('theme_handler')->listInfo();
  foreach ($themes as $theme) {
    _block_rehash($theme->getName());
  }
}

/**
 * Define the current version of the database schema.
 *
 * A Drupal schema definition is an array structure representing one or more
 * tables and their related keys and indexes. A schema is defined by
 * hook_schema() which must live in your module's .install file.
 *
 * The tables declared by this hook will be automatically created when the
 * module is installed, and removed when the module is uninstalled. This happens
 * before hook_install() is invoked, and after hook_uninstall() is invoked,
 * respectively.
 *
 * By declaring the tables used by your module via an implementation of
 * hook_schema(), these tables will be available on all supported database
 * engines. You don't have to deal with the different SQL dialects for table
 * creation and alteration of the supported database engines.
 *
 * See the Schema API Handbook at http://drupal.org/node/146843 for details on
 * schema definition structures.
 *
 * @return array
 *   A schema definition structure array. For each element of the
 *   array, the key is a table name and the value is a table structure
 *   definition.
 *
 * @see hook_schema_alter()
 *
 * @ingroup schemaapi
 */
function hook_schema() {
  $schema['node'] = array(
    // Example (partial) specification for table "node".
    'description' => 'The base table for nodes.',
    'fields' => array(
      'nid' => array(
        'description' => 'The primary identifier for a node.',
        'type' => 'serial',
        'unsigned' => TRUE,
        'not null' => TRUE,
      ),
      'vid' => array(
        'description' => 'The current {node_field_revision}.vid version identifier.',
        'type' => 'int',
        'unsigned' => TRUE,
        'not null' => TRUE,
        'default' => 0,
      ),
      'type' => array(
        'description' => 'The type of this node.',
        'type' => 'varchar',
        'length' => 32,
        'not null' => TRUE,
        'default' => '',
      ),
      'title' => array(
        'description' => 'The node title.',
        'type' => 'varchar',
        'length' => 255,
        'not null' => TRUE,
        'default' => '',
      ),
    ),
    'indexes' => array(
      'node_changed'        => array('changed'),
      'node_created'        => array('created'),
    ),
    'unique keys' => array(
      'nid_vid' => array('nid', 'vid'),
      'vid'     => array('vid'),
    ),
    'foreign keys' => array(
      'node_revision' => array(
        'table' => 'node_field_revision',
        'columns' => array('vid' => 'vid'),
      ),
      'node_author' => array(
        'table' => 'users',
        'columns' => array('uid' => 'uid'),
      ),
    ),
    'primary key' => array('nid'),
  );
  return $schema;
}

/**
 * Perform alterations to existing database schemas.
 *
 * When a module modifies the database structure of another module (by
 * changing, adding or removing fields, keys or indexes), it should
 * implement hook_schema_alter() to update the default $schema to take its
 * changes into account.
 *
 * See hook_schema() for details on the schema definition structure.
 *
 * @param $schema
 *   Nested array describing the schemas for all modules.
 *
 * @ingroup schemaapi
 */
function hook_schema_alter(&$schema) {
  // Add field to existing schema.
  $schema['users']['fields']['timezone_id'] = array(
    'type' => 'int',
    'not null' => TRUE,
    'default' => 0,
    'description' => 'Per-user timezone configuration.',
  );
}

/**
 * Perform alterations to a structured query.
 *
 * Structured (aka dynamic) queries that have tags associated may be altered by any module
 * before the query is executed.
 *
 * @param $query
 *   A Query object describing the composite parts of a SQL query.
 *
 * @see hook_query_TAG_alter()
 * @see node_query_node_access_alter()
 * @see AlterableInterface
 * @see SelectInterface
 */
function hook_query_alter(Drupal\Core\Database\Query\AlterableInterface $query) {
  if ($query->hasTag('micro_limit')) {
    $query->range(0, 2);
  }
}

/**
 * Perform alterations to a structured query for a given tag.
 *
 * @param $query
 *   An Query object describing the composite parts of a SQL query.
 *
 * @see hook_query_alter()
 * @see node_query_node_access_alter()
 * @see AlterableInterface
 * @see SelectInterface
 */
function hook_query_TAG_alter(Drupal\Core\Database\Query\AlterableInterface $query) {
  // Skip the extra expensive alterations if site has no node access control modules.
  if (!node_access_view_all_nodes()) {
    // Prevent duplicates records.
    $query->distinct();
    // The recognized operations are 'view', 'update', 'delete'.
    if (!$op = $query->getMetaData('op')) {
      $op = 'view';
    }
    // Skip the extra joins and conditions for node admins.
    if (!\Drupal::currentUser()->hasPermission('bypass node access')) {
      // The node_access table has the access grants for any given node.
      $access_alias = $query->join('node_access', 'na', '%alias.nid = n.nid');
      $or = db_or();
      // If any grant exists for the specified user, then user has access to the node for the specified operation.
      foreach (node_access_grants($op, $query->getMetaData('account')) as $realm => $gids) {
        foreach ($gids as $gid) {
          $or->condition(db_and()
            ->condition($access_alias . '.gid', $gid)
            ->condition($access_alias . '.realm', $realm)
          );
        }
      }

      if (count($or->conditions())) {
        $query->condition($or);
      }

      $query->condition($access_alias . 'grant_' . $op, 1, '>=');
    }
  }
}

/**
 * Alters theme operation links.
 *
 * @param $theme_groups
 *   An associative array containing groups of themes.
 *
 * @see system_themes_page()
 */
function hook_system_themes_page_alter(&$theme_groups) {
  foreach ($theme_groups as $state => &$group) {
    foreach ($theme_groups[$state] as &$theme) {
      // Add a foo link to each list of theme operations.
      $theme->operations[] = array(
        'title' => t('Foo'),
        'url' => Url::fromRoute('system.themes_page'),
        'query' => array('theme' => $theme->getName())
      );
    }
  }
}

/**
 * Provide replacement values for placeholder tokens.
 *
 * This hook is invoked when someone calls
 * \Drupal\Core\Utility\Token::replace(). That function first scans the text for
 * [type:token] patterns, and splits the needed tokens into groups by type.
 * Then hook_tokens() is invoked on each token-type group, allowing your module
 * to respond by providing replacement text for any of the tokens in the group
 * that your module knows how to process.
 *
 * A module implementing this hook should also implement hook_token_info() in
 * order to list its available tokens on editing screens.
 *
 * @param $type
 *   The machine-readable name of the type (group) of token being replaced, such
 *   as 'node', 'user', or another type defined by a hook_token_info()
 *   implementation.
 * @param $tokens
 *   An array of tokens to be replaced. The keys are the machine-readable token
 *   names, and the values are the raw [type:token] strings that appeared in the
 *   original text.
 * @param $data
 *   (optional) An associative array of data objects to be used when generating
 *   replacement values, as supplied in the $data parameter to
 *   \Drupal\Core\Utility\Token::replace().
 * @param $options
 *   (optional) An associative array of options for token replacement; see
 *   \Drupal\Core\Utility\Token::replace() for possible values.
 *
 * @return
 *   An associative array of replacement values, keyed by the raw [type:token]
 *   strings from the original text.
 *
 * @see hook_token_info()
 * @see hook_tokens_alter()
 */
function hook_tokens($type, $tokens, array $data = array(), array $options = array()) {
  $token_service = \Drupal::token();

  $url_options = array('absolute' => TRUE);
  if (isset($options['langcode'])) {
    $url_options['language'] = \Drupal::languageManager()->getLanguage($options['langcode']);
    $langcode = $options['langcode'];
  }
  else {
    $langcode = NULL;
  }
  $sanitize = !empty($options['sanitize']);

  $replacements = array();

  if ($type == 'node' && !empty($data['node'])) {
    /** @var \Drupal\node\NodeInterface $node */
    $node = $data['node'];

    foreach ($tokens as $name => $original) {
      switch ($name) {
        // Simple key values on the node.
        case 'nid':
          $replacements[$original] = $node->nid;
          break;

        case 'title':
          $replacements[$original] = $sanitize ? SafeMarkup::checkPlain($node->getTitle()) : $node->getTitle();
          break;

        case 'edit-url':
          $replacements[$original] = $node->url('edit-form', $url_options);
          break;

        // Default values for the chained tokens handled below.
        case 'author':
          $account = $node->getOwner() ? $node->getOwner() : user_load(0);
          $replacements[$original] = $sanitize ? SafeMarkup::checkPlain($account->label()) : $account->label();
          break;

        case 'created':
          $replacements[$original] = format_date($node->getCreatedTime(), 'medium', '', NULL, $langcode);
          break;
      }
    }

    if ($author_tokens = $token_service->findWithPrefix($tokens, 'author')) {
      $replacements += $token_service->generate('user', $author_tokens, array('user' => $node->getOwner()), $options);
    }

    if ($created_tokens = $token_service->findWithPrefix($tokens, 'created')) {
      $replacements += $token_service->generate('date', $created_tokens, array('date' => $node->getCreatedTime()), $options);
    }
  }

  return $replacements;
}

/**
 * Alter replacement values for placeholder tokens.
 *
 * @param $replacements
 *   An associative array of replacements returned by hook_tokens().
 * @param $context
 *   The context in which hook_tokens() was called. An associative array with
 *   the following keys, which have the same meaning as the corresponding
 *   parameters of hook_tokens():
 *   - 'type'
 *   - 'tokens'
 *   - 'data'
 *   - 'options'
 *
 * @see hook_tokens()
 */
function hook_tokens_alter(array &$replacements, array $context) {
  $options = $context['options'];

  if (isset($options['langcode'])) {
    $url_options['language'] = \Drupal::languageManager()->getLanguage($options['langcode']);
    $langcode = $options['langcode'];
  }
  else {
    $langcode = NULL;
  }

  if ($context['type'] == 'node' && !empty($context['data']['node'])) {
    $node = $context['data']['node'];

    // Alter the [node:title] token, and replace it with the rendered content
    // of a field (field_title).
    if (isset($context['tokens']['title'])) {
      $title = $node->field_title->view('default');
      $replacements[$context['tokens']['title']] = drupal_render($title);
    }
  }
}

/**
 * Provide information about available placeholder tokens and token types.
 *
 * Tokens are placeholders that can be put into text by using the syntax
 * [type:token], where type is the machine-readable name of a token type, and
 * token is the machine-readable name of a token within this group. This hook
 * provides a list of types and tokens to be displayed on text editing screens,
 * so that people editing text can see what their token options are.
 *
 * The actual token replacement is done by
 * \Drupal\Core\Utility\Token::replace(), which invokes hook_tokens(). Your
 * module will need to implement that hook in order to generate token
 * replacements from the tokens defined here.
 *
 * @return
 *   An associative array of available tokens and token types. The outer array
 *   has two components:
 *   - types: An associative array of token types (groups). Each token type is
 *     an associative array with the following components:
 *     - name: The translated human-readable short name of the token type.
 *     - description (optional): A translated longer description of the token
 *       type.
 *     - needs-data: The type of data that must be provided to
 *       \Drupal\Core\Utility\Token::replace() in the $data argument (i.e., the
 *       key name in $data) in order for tokens of this type to be used in the
 *       $text being processed. For instance, if the token needs a node object,
 *       'needs-data' should be 'node', and to use this token in
 *       \Drupal\Core\Utility\Token::replace(), the caller needs to supply a
 *       node object as $data['node']. Some token data can also be supplied
 *       indirectly; for instance, a node object in $data supplies a user object
 *       (the author of the node), allowing user tokens to be used when only
 *       a node data object is supplied.
 *   - tokens: An associative array of tokens. The outer array is keyed by the
 *     group name (the same key as in the types array). Within each group of
 *     tokens, each token item is keyed by the machine name of the token, and
 *     each token item has the following components:
 *     - name: The translated human-readable short name of the token.
 *     - description (optional): A translated longer description of the token.
 *     - type (optional): A 'needs-data' data type supplied by this token, which
 *       should match a 'needs-data' value from another token type. For example,
 *       the node author token provides a user object, which can then be used
 *       for token replacement data in \Drupal\Core\Utility\Token::replace()
 *       without having to supply a separate user object.
 *
 * @see hook_token_info_alter()
 * @see hook_tokens()
 */
function hook_token_info() {
  $type = array(
    'name' => t('Nodes'),
    'description' => t('Tokens related to individual nodes.'),
    'needs-data' => 'node',
  );

  // Core tokens for nodes.
  $node['nid'] = array(
    'name' => t("Node ID"),
    'description' => t("The unique ID of the node."),
  );
  $node['title'] = array(
    'name' => t("Title"),
  );
  $node['edit-url'] = array(
    'name' => t("Edit URL"),
    'description' => t("The URL of the node's edit page."),
  );

  // Chained tokens for nodes.
  $node['created'] = array(
    'name' => t("Date created"),
    'type' => 'date',
  );
  $node['author'] = array(
    'name' => t("Author"),
    'type' => 'user',
  );

  return array(
    'types' => array('node' => $type),
    'tokens' => array('node' => $node),
  );
}

/**
 * Alter the metadata about available placeholder tokens and token types.
 *
 * @param $data
 *   The associative array of token definitions from hook_token_info().
 *
 * @see hook_token_info()
 */
function hook_token_info_alter(&$data) {
  // Modify description of node tokens for our site.
  $data['tokens']['node']['nid'] = array(
    'name' => t("Node ID"),
    'description' => t("The unique ID of the article."),
  );
  $data['tokens']['node']['title'] = array(
    'name' => t("Title"),
    'description' => t("The title of the article."),
  );

  // Chained tokens for nodes.
  $data['tokens']['node']['created'] = array(
    'name' => t("Date created"),
    'description' => t("The date the article was posted."),
    'type' => 'date',
  );
}

/**
 * Alter the parameters for links.
 *
 * @param array $variables
 *   An associative array of variables defining a link. The link may be either a
 *   "route link" using \Drupal\Core\Utility\LinkGenerator::link(), which is
 *   exposed as the 'link_generator' service or a link generated by _l(). If the
 *   link is a "route link", 'route_name' will be set, otherwise 'path' will be
 *   set. The following keys can be altered:
 *   - text: The link text for the anchor tag as a translated string.
 *   - url_is_active: Whether or not the link points to the currently active
 *     URL.
 *   - url: The \Drupal\Core\Url object.
 *   - options: An associative array of additional options that will be passed
 *     to either \Drupal\Core\Routing\UrlGenerator::generateFromPath() or
 *     \Drupal\Core\Routing\UrlGenerator::generateFromRoute() to generate the
 *     href attribute for this link, and also used when generating the link.
 *     Defaults to an empty array. It may contain the following elements:
 *     - 'query': An array of query key/value-pairs (without any URL-encoding) to
 *       append to the URL.
 *     - absolute: Whether to force the output to be an absolute link (beginning
 *       with http:). Useful for links that will be displayed outside the site,
 *       such as in an RSS feed. Defaults to FALSE.
 *     - language: An optional language object. May affect the rendering of
 *       the anchor tag, such as by adding a language prefix to the path.
 *     - attributes: An associative array of HTML attributes to apply to the
 *       anchor tag. If element 'class' is included, it must be an array; 'title'
 *       must be a string; other elements are more flexible, as they just need
 *       to work as an argument for the constructor of the class
 *       Drupal\Core\Template\Attribute($options['attributes']).
 *     - html: Whether or not HTML should be allowed as the link text. If FALSE,
 *       the text will be run through
 *       \Drupal\Component\Utility\SafeMarkup::checkPlain() before being output.
 *
 * @see \Drupal\Core\Routing\UrlGenerator::generateFromPath()
 * @see \Drupal\Core\Routing\UrlGenerator::generateFromRoute()
 */
function hook_link_alter(&$variables) {
  // Add a warning to the end of route links to the admin section.
  if (isset($variables['route_name']) && strpos($variables['route_name'], 'admin') !== FALSE) {
    $variables['text'] .= ' (Warning!)';
  }
}

/**
 * Alter the configuration synchronization steps.
 *
 * @param array $sync_steps
 *   A one-dimensional array of \Drupal\Core\Config\ConfigImporter method names
 *   or callables that are invoked to complete the import, in the order that
 *   they will be processed. Each callable item defined in $sync_steps should
 *   either be a global function or a public static method. The callable should
 *   accept a $context array by reference. For example:
 *   <code>
 *     function _additional_configuration_step(&$context) {
 *       // Do stuff.
 *       // If finished set $context['finished'] = 1.
 *     }
 *   </code>
 *   For more information on creating batches, see the
 *   @link batch Batch operations @endlink documentation.
 *
 * @see callback_batch_operation()
 * @see \Drupal\Core\Config\ConfigImporter::initialize()
 */
function hook_config_import_steps_alter(&$sync_steps, \Drupal\Core\Config\ConfigImporter $config_importer) {
  $deletes = $config_importer->getUnprocessedConfiguration('delete');
  if (isset($deletes['field.storage.node.body'])) {
    $sync_steps[] = '_additional_configuration_step';
  }
}

/**
 * Alter config typed data definitions.
 *
 * For example you can alter the typed data types representing each
 * configuration schema type to change default labels or form element renderers
 * used for configuration translation.
 *
 * If implementations of this hook add or remove configuration schema a
 * ConfigSchemaAlterException will be thrown. Keep in mind that there are tools
 * that may use the configuration schema for static analysis of configuration
 * files, like the string extractor for the localization system. Such systems
 * won't work with dynamically defined configuration schemas.
 *
 * For adding new data types use configuration schema YAML files instead.
 *
 * @param $definitions
 *   Associative array of configuration type definitions keyed by schema type
 *   names. The elements are themselves array with information about the type.
 *
 * @see \Drupal\Core\Config\TypedConfigManager
 * @see \Drupal\Core\Config\Schema\ConfigSchemaAlterException
 */
function hook_config_schema_info_alter(&$definitions) {
  // Enhance the text and date type definitions with classes to generate proper
  // form elements in ConfigTranslationFormBase. Other translatable types will
  // appear as a one line textfield.
  $definitions['text']['form_element_class'] = '\Drupal\config_translation\FormElement\Textarea';
  $definitions['date_format']['form_element_class'] = '\Drupal\config_translation\FormElement\DateFormat';
}

/**
 * @} End of "addtogroup hooks".
 */