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Drupal example source code file (node.api.php)

This example Drupal source code file (node.api.php) is included in the DevDaily.com "Drupal Source Code Warehouse" project. The intent of this project is to help you "Learn Drupal by Example".

PHP - Drupal tags/keywords

account, array, callback, content, file, foreach, function, grants, if, nid, node, php, return, type

The node.api.php Drupal example source code

<?php
// $Id: node.api.php,v 1.83 2011/01/03 18:03:54 webchick Exp $

/**
 * @file
 * Hooks provided by the Node module.
 */

/**
 * @defgroup node_api_hooks Node API Hooks
 * @{
 * Functions to define and modify content types.
 *
 * Each content type is maintained by a primary module, which is either
 * node.module (for content types created in the user interface) or the
 * module that implements hook_node_info() to define the content type.
 *
 * During node operations (create, update, view, delete, etc.), there are
 * several sets of hooks that get invoked to allow modules to modify the base
 * node operation:
 * - Node-type-specific hooks: These hooks are only invoked on the primary
 *   module, using the "base" return component of hook_node_info() as the
 *   function prefix.  For example, poll.module defines the base for the Poll
 *   content type as "poll", so during creation of a poll node, hook_insert() is
 *   only invoked by calling poll_insert().
 * - All-module hooks: This set of hooks is invoked on all implementing
 *   modules, to allow other modules to modify what the primary node module is
 *   doing. For example, hook_node_insert() is invoked on all modules when
 *   creating a poll node.
 * - Field hooks: Hooks related to the fields attached to the node. These are
 *   invoked from the field operations functions described below, and can be
 *   either field-type-specific or all-module hooks.
 * - Entity hooks: Generic hooks for "entity" operations. These are always
 *   invoked on all modules.
 *
 * Here is a list of the node and entity hooks that are invoked, field
 * operations, and other steps that take place during node operations:
 * - Creating a new node (calling node_save() on a new node):
 *   - field_attach_presave()
 *   - hook_node_presave() (all)
 *   - Node and revision records are written to the database
 *   - hook_insert() (node-type-specific)
 *   - field_attach_insert()
 *   - hook_node_insert() (all)
 *   - hook_entity_insert() (all)
 *   - hook_node_access_records() (all)
 *   - hook_node_access_records_alter() (all)
 * - Updating an existing node (calling node_save() on an existing node):
 *   - field_attach_presave()
 *   - hook_node_presave() (all)
 *   - Node and revision records are written to the database
 *   - hook_update() (node-type-specific)
 *   - field_attach_update()
 *   - hook_node_update() (all)
 *   - hook_entity_update() (all)
 *   - hook_node_access_records() (all)
 *   - hook_node_access_records_alter() (all)
 * - Loading a node (calling node_load(), node_load_multiple(), or
 *   entity_load() with $entity_type of 'node'):
 *   - Node and revision information is read from database.
 *   - hook_load() (node-type-specific)
 *   - field_attach_load_revision() and field_attach_load()
 *   - hook_entity_load() (all)
 *   - hook_node_load() (all)
 * - Viewing a single node (calling node_view() - note that the input to
 *   node_view() is a loaded node, so the Loading steps above are already
 *   done):
 *   - hook_view() (node-type-specific)
 *   - field_attach_prepare_view()
 *   - hook_entity_prepare_view() (all)
 *   - field_attach_view()
 *   - hook_node_view() (all)
 * - Viewing multiple nodes (calling node_view_multiple() - note that the input
 *   to node_view_multiple() is a set of loaded nodes, so the Loading steps
 *   above are already done):
 *   - field_attach_prepare_view()
 *   - hook_entity_prepare_view() (all)
 *   - hook_view() (node-type-specific)
 *   - field_attach_view()
 *   - hook_node_view() (all)
 *   - hook_node_view_alter() (all)
 * - Deleting a node (calling node_delete() or node_delete_multiple()):
 *   - Node is loaded (see Loading section above)
 *   - Node and revision information is deleted from database
 *   - hook_delete() (node-type-specific)
 *   - hook_node_delete() (all)
 *   - field_attach_delete()
 * - Deleting a node revision (calling node_revision_delete()):
 *   - Node is loaded (see Loading section above)
 *   - Revision information is deleted from database
 *   - hook_node_revision_delete() (all)
 *   - field_attach_delete_revision()
 * - Preparing a node for editing (calling node_form() - note that if it's
 *   an existing node, it will already be loaded; see the Loading section
 *   above):
 *   - hook_prepare() (node-type-specific)
 *   - hook_node_prepare() (all)
 *   - hook_form() (node-type-specific)
 *   - field_attach_form()
 * - Validating a node during editing form submit (calling
 *   node_form_validate()):
 *   - hook_validate() (node-type-specific)
 *   - hook_node_validate() (all)
 *   - field_attach_form_validate()
 * - Searching (calling node_search_execute()):
 *   - hook_ranking() (all)
 *   - Query is executed to find matching nodes
 *   - Resulting node is loaded (see Loading section above)
 *   - Resulting node is prepared for viewing (see Viewing a single node above)
 *   - comment_node_update_index() is called.
 *   - hook_node_search_result() (all)
 * - Search indexing (calling node_update_index()):
 *   - Node is loaded (see Loading section above)
 *   - Node is prepared for viewing (see Viewing a single node above)
 *   - hook_node_update_index() (all)
 * @}
 */

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

/**
 * Inform the node access system what permissions the user has.
 *
 * This hook is for implementation by node access modules. In this hook,
 * the module grants a user different "grant IDs" within one or more
 * "realms". In hook_node_access_records(), the realms and grant IDs are
 * associated with permission to view, edit, and delete individual nodes.
 *
 * The realms and grant IDs can be arbitrarily defined by your node access
 * module; it is common to use role IDs as grant IDs, but that is not
 * required. Your module could instead maintain its own list of users, where
 * each list has an ID. In that case, the return value of this hook would be
 * an array of the list IDs that this user is a member of.
 *
 * A node access module may implement as many realms as necessary to
 * properly define the access privileges for the nodes. Note that the system
 * makes no distinction between published and unpublished nodes. It is the
 * module's responsibility to provide appropriate realms to limit access to
 * unpublished content.
 *
 * Node access records are stored in the {node_access} table and define which
 * grants are required to access a node. There is a special case for the view
 * operation -- a record with node ID 0 corresponds to a "view all" grant for
 * the realm and grant ID of that record. If there are no node access modules
 * enabled, the core node module adds a node ID 0 record for realm 'all'. Node
 * access modules can also grant "view all" permission on their custom realms;
 * for example, a module could create a record in {node_access} with:
 * @code
 * $record = array(
 *   'nid' => 0,
 *   'gid' => 888,
 *   'realm' => 'example_realm',
 *   'grant_view' => 1,
 *   'grant_update' => 0,
 *   'grant_delete' => 0,
 * );
 * drupal_write_record('node_access', $record);
 * @endcode
 * And then in its hook_node_grants() implementation, it would need to return:
 * @code
 * if ($op == 'view') {
 *   $grants['example_realm'] = array(888);
 * }
 * @endcode
 * If you decide to do this, be aware that the node_access_rebuild() function
 * will erase any node ID 0 entry when it is called, so you will need to make
 * sure to restore your {node_access} record after node_access_rebuild() is
 * called.
 *
 * @see node_access_view_all_nodes()
 * @see node_access_rebuild()
 *
 * @param $account
 *   The user object whose grants are requested.
 * @param $op
 *   The node operation to be performed, such as "view", "update", or "delete".
 *
 * @return
 *   An array whose keys are "realms" of grants, and whose values are arrays of
 *   the grant IDs within this realm that this user is being granted.
 *
 * For a detailed example, see node_access_example.module.
 *
 * @ingroup node_access
 */
function hook_node_grants($account, $op) {
  if (user_access('access private content', $account)) {
    $grants['example'] = array(1);
  }
  $grants['example_owner'] = array($account->uid);
  return $grants;
}

/**
 * Set permissions for a node to be written to the database.
 *
 * When a node is saved, a module implementing hook_node_access_records() will
 * be asked if it is interested in the access permissions for a node. If it is
 * interested, it must respond with an array of permissions arrays for that
 * node.
 *
 * Node access grants apply regardless of the published or unpublished status
 * of the node. Implementations must make sure not to grant access to
 * unpublished nodes if they don't want to change the standard access control
 * behavior. Your module may need to create a separate access realm to handle
 * access to unpublished nodes.
 *
 * Note that the grant values in the return value from your hook must be
 * integers and not boolean TRUE and FALSE.
 *
 * Each permissions item in the array is an array with the following elements:
 * - 'realm': The name of a realm that the module has defined in
 *   hook_node_grants().
 * - 'gid': A 'grant ID' from hook_node_grants().
 * - 'grant_view': If set to 1 a user that has been identified as a member
 *   of this gid within this realm can view this node. This should usually be
 *   set to $node->status. Failure to do so may expose unpublished content
 *   to some users.
 * - 'grant_update': If set to 1 a user that has been identified as a member
 *   of this gid within this realm can edit this node.
 * - 'grant_delete': If set to 1 a user that has been identified as a member
 *   of this gid within this realm can delete this node.
 * - 'priority': If multiple modules seek to set permissions on a node, the
 *   realms that have the highest priority will win out, and realms with a lower
 *   priority will not be written. If there is any doubt, it is best to
 *   leave this 0.
 *
 *
 * When an implementation is interested in a node but want to deny access to
 * everyone, it may return a "deny all" grant:
 *
 * @code
 * $grants[] = array(
 *   'realm' => 'all',
 *   'gid' => 0,
 *   'grant_view' => 0,
 *   'grant_update' => 0,
 *   'grant_delete' => 0,
 *   'priority' => 1,
 * );
 * @endcode
 *
 * Setting the priority should cancel out other grants. In the case of a
 * conflict between modules, it is safer to use hook_node_access_records_alter()
 * to return only the deny grant.
 *
 * Note: a deny all grant is not written to the database; denies are implicit.
 *
 * @see node_access_write_grants()
 *
 * @param $node
 *   The node that has just been saved.
 *
 * @return
 *   An array of grants as defined above.
 *
 * @ingroup node_access
 */
function hook_node_access_records($node) {
  // We only care about the node if it has been marked private. If not, it is
  // treated just like any other node and we completely ignore it.
  if ($node->private) {
    $grants = array();
    // Only published nodes should be viewable to all users. If we allow access
    // blindly here, then all users could view an unpublished node.
    if ($node->status) {
      $grants[] = array(
        'realm' => 'example',
        'gid' => 1,
        'grant_view' => 1,
        'grant_update' => 0,
        'grant_delete' => 0,
        'priority' => 0,
      );
    }
    // For the example_author array, the GID is equivalent to a UID, which
    // means there are many groups of just 1 user.
    // Note that an author can always view his or her nodes, even if they
    // have status unpublished.
    $grants[] = array(
      'realm' => 'example_author',
      'gid' => $node->uid,
      'grant_view' => 1,
      'grant_update' => 1,
      'grant_delete' => 1,
      'priority' => 0,
    );

    return $grants;
  }
}

/**
 * Alter permissions for a node before it is written to the database.
 *
 * Node access modules establish rules for user access to content. Node access
 * records are stored in the {node_access} table and define which permissions
 * are required to access a node. This hook is invoked after node access modules
 * returned their requirements via hook_node_access_records(); doing so allows
 * modules to modify the $grants array by reference before it is stored, so
 * custom or advanced business logic can be applied.
 *
 * @see hook_node_access_records()
 *
 * Upon viewing, editing or deleting a node, hook_node_grants() builds a
 * permissions array that is compared against the stored access records. The
 * user must have one or more matching permissions in order to complete the
 * requested operation.
 *
 * A module may deny all access to a node by setting $grants to an empty array.
 *
 * @see hook_node_grants()
 * @see hook_node_grants_alter()
 *
 * @param &$grants
 *   The $grants array returned by hook_node_access_records().
 * @param $node
 *   The node for which the grants were acquired.
 *
 * The preferred use of this hook is in a module that bridges multiple node
 * access modules with a configurable behavior, as shown in the example with the
 * 'is_preview' field.
 *
 * @ingroup node_access
 */
function hook_node_access_records_alter(&$grants, $node) {
  // Our module allows editors to mark specific articles with the 'is_preview'
  // field. If the node being saved has a TRUE value for that field, then only
  // our grants are retained, and other grants are removed. Doing so ensures
  // that our rules are enforced no matter what priority other grants are given.
  if ($node->is_preview) {
    // Our module grants are set in $grants['example'].
    $temp = $grants['example'];
    // Now remove all module grants but our own.
    $grants = array('example' => $temp);
  }
}

/**
 * Alter user access rules when trying to view, edit or delete a node.
 *
 * Node access modules establish rules for user access to content.
 * hook_node_grants() defines permissions for a user to view, edit or
 * delete nodes by building a $grants array that indicates the permissions
 * assigned to the user by each node access module. This hook is called to allow
 * modules to modify the $grants array by reference, so the interaction of
 * multiple node access modules can be altered or advanced business logic can be
 * applied.
 *
 * @see hook_node_grants()
 *
 * The resulting grants are then checked against the records stored in the
 * {node_access} table to determine if the operation may be completed.
 *
 * A module may deny all access to a user by setting $grants to an empty array.
 *
 * @see hook_node_access_records()
 * @see hook_node_access_records_alter()
 *
 * @param &$grants
 *   The $grants array returned by hook_node_grants().
 * @param $account
 *   The user account requesting access to content.
 * @param $op
 *   The operation being performed, 'view', 'update' or 'delete'.
 *
 * Developers may use this hook to either add additional grants to a user
 * or to remove existing grants. These rules are typically based on either the
 * permissions assigned to a user role, or specific attributes of a user
 * account.
 *
 * @ingroup node_access
 */
function hook_node_grants_alter(&$grants, $account, $op) {
  // Our sample module never allows certain roles to edit or delete
  // content. Since some other node access modules might allow this
  // permission, we expressly remove it by returning an empty $grants
  // array for roles specified in our variable setting.

  // Get our list of banned roles.
  $restricted = variable_get('example_restricted_roles', array());

  if ($op != 'view' && !empty($restricted)) {
    // Now check the roles for this account against the restrictions.
    foreach ($restricted as $role_id) {
      if (isset($user->roles[$role_id])) {
        $grants = array();
      }
    }
  }
}

/**
 * Add mass node operations.
 *
 * This hook enables modules to inject custom operations into the mass
 * operations dropdown found at admin/content, by associating a callback
 * function with the operation, which is called when the form is submitted. The
 * callback function receives one initial argument, which is an array of the
 * checked nodes.
 *
 * @return
 *   An array of operations. Each operation is an associative array that may
 *   contain the following key-value pairs:
 *   - 'label': Required. The label for the operation, displayed in the dropdown
 *     menu.
 *   - 'callback': Required. The function to call for the operation.
 *   - 'callback arguments': Optional. An array of additional arguments to pass
 *     to the callback function.
 */
function hook_node_operations() {
  $operations = array(
    'publish' => array(
      'label' => t('Publish selected content'),
      'callback' => 'node_mass_update',
      'callback arguments' => array('updates' => array('status' => NODE_PUBLISHED)),
    ),
    'unpublish' => array(
      'label' => t('Unpublish selected content'),
      'callback' => 'node_mass_update',
      'callback arguments' => array('updates' => array('status' => NODE_NOT_PUBLISHED)),
    ),
    'promote' => array(
      'label' => t('Promote selected content to front page'),
      'callback' => 'node_mass_update',
      'callback arguments' => array('updates' => array('status' => NODE_PUBLISHED, 'promote' => NODE_PROMOTED)),
    ),
    'demote' => array(
      'label' => t('Demote selected content from front page'),
      'callback' => 'node_mass_update',
      'callback arguments' => array('updates' => array('promote' => NODE_NOT_PROMOTED)),
    ),
    'sticky' => array(
      'label' => t('Make selected content sticky'),
      'callback' => 'node_mass_update',
      'callback arguments' => array('updates' => array('status' => NODE_PUBLISHED, 'sticky' => NODE_STICKY)),
    ),
    'unsticky' => array(
      'label' => t('Make selected content not sticky'),
      'callback' => 'node_mass_update',
      'callback arguments' => array('updates' => array('sticky' => NODE_NOT_STICKY)),
    ),
    'delete' => array(
      'label' => t('Delete selected content'),
      'callback' => NULL,
    ),
  );
  return $operations;
}

/**
 * Respond to node deletion.
 *
 * This hook is invoked from node_delete_multiple() after the node has been
 * removed from the node table in the database, after the type-specific
 * hook_delete() has been invoked, and before field_attach_delete() is called.
 *
 * @param $node
 *   The node that is being deleted.
 *
 * @ingroup node_api_hooks
 */
function hook_node_delete($node) {
  db_delete('mytable')
    ->condition('nid', $node->nid)
    ->execute();
}

/**
 * Respond to deletion of a node revision.
 *
 * This hook is invoked from node_revision_delete() after the revision has been
 * removed from the node_revision table, and before
 * field_attach_delete_revision() is called.
 *
 * @param $node
 *   The node revision (node object) that is being deleted.
 *
 * @ingroup node_api_hooks
 */
function hook_node_revision_delete($node) {
  db_delete('mytable')
    ->condition('vid', $node->vid)
    ->execute();
}

/**
 * Respond to creation of a new node.
 *
 * This hook is invoked from node_save() after the node is inserted into the
 * node table in the database, after the type-specific hook_insert() is invoked,
 * and after field_attach_insert() is called.
 *
 * @param $node
 *   The node that is being created.
 *
 * @ingroup node_api_hooks
 */
function hook_node_insert($node) {
  db_insert('mytable')
    ->fields(array(
      'nid' => $node->nid,
      'extra' => $node->extra,
    ))
    ->execute();
}

/**
 * Act on nodes being loaded from the database.
 *
 * This hook is invoked during node loading, which is handled by entity_load(),
 * via classes NodeController and DrupalDefaultEntityController. After the node
 * information is read from the database or the entity cache, hook_load() is
 * invoked on the node's content type module, then field_attach_node_revision()
 * or field_attach_load() is called, then hook_entity_load() is invoked on all
 * implementing modules, and finally hook_node_load() is invoked on all
 * implementing modules.
 *
 * This hook should only be used to add information that is not in the node or
 * node revisions table, not to replace information that is in these tables
 * (which could interfere with the entity cache). For performance reasons,
 * information for all available nodes should be loaded in a single query where
 * possible.
 *
 * The $types parameter allows for your module to have an early return (for
 * efficiency) if your module only supports certain node types. However, if your
 * module defines a content type, you can use hook_load() to respond to loading
 * of just that content type.
 *
 * @param $nodes
 *   An array of the nodes being loaded, keyed by nid.
 * @param $types
 *   An array containing the types of the nodes.
 *
 * For a detailed usage example, see nodeapi_example.module.
 *
 * @ingroup node_api_hooks
 */
function hook_node_load($nodes, $types) {
  $result = db_query('SELECT nid, foo FROM {mytable} WHERE nid IN(:nids)', array(':nids' => array_keys($nodes)));
  foreach ($result as $record) {
    $nodes[$record->nid]->foo = $record->foo;
  }
}

/**
 * Control access to a node.
 *
 * Modules may implement this hook if they want to have a say in whether or not
 * a given user has access to perform a given operation on a node.
 *
 * The administrative account (user ID #1) always passes any access check,
 * so this hook is not called in that case. Users with the "bypass node access"
 * permission may always view and edit content through the administrative
 * interface.
 *
 * Note that not all modules will want to influence access on all
 * node types. If your module does not want to actively grant or
 * block access, return NODE_ACCESS_IGNORE or simply return nothing.
 * Blindly returning FALSE will break other node access modules.
 *
 * @link http://api.drupal.org/api/group/node_access/7 More on the node access system @endlink
 * @ingroup node_access
 * @param $node
 *   The node on which the operation is to be performed, or, if it does
 *   not yet exist, the type of node to be created.
 * @param $op
 *   The operation to be performed. Possible values:
 *   - "create"
 *   - "delete"
 *   - "update"
 *   - "view"
 * @param $account
 *   A user object representing the user for whom the operation is to be
 *   performed.
 *
 * @return
 *   NODE_ACCESS_ALLOW if the operation is to be allowed;
 *   NODE_ACCESS_DENY if the operation is to be denied;
 *   NODE_ACCESSS_IGNORE to not affect this operation at all.
 */
function hook_node_access($node, $op, $account) {
  $type = is_string($node) ? $node : $node->type;

  if (in_array($type, node_permissions_get_configured_types())) {
    if ($op == 'create' && user_access('create ' . $type . ' content', $account)) {
      return NODE_ACCESS_ALLOW;
    }

    if ($op == 'update') {
      if (user_access('edit any ' . $type . ' content', $account) || (user_access('edit own ' . $type . ' content', $account) && ($account->uid == $node->uid))) {
        return NODE_ACCESS_ALLOW;
      }
    }

    if ($op == 'delete') {
      if (user_access('delete any ' . $type . ' content', $account) || (user_access('delete own ' . $type . ' content', $account) && ($account->uid == $node->uid))) {
        return NODE_ACCESS_ALLOW;
      }
    }
  }

  // Returning nothing from this function would have the same effect.
  return NODE_ACCESS_IGNORE;
}


/**
 * Act on a node object about to be shown on the add/edit form.
 *
 * This hook is invoked from node_object_prepare() after the type-specific
 * hook_prepare() is invoked.
 *
 * @param $node
 *   The node that is about to be shown on the add/edit form.
 *
 * @ingroup node_api_hooks
 */
function hook_node_prepare($node) {
  if (!isset($node->comment)) {
    $node->comment = variable_get("comment_$node->type", COMMENT_NODE_OPEN);
  }
}

/**
 * Act on a node being displayed as a search result.
 *
 * This hook is invoked from node_search_execute(), after node_load()
 * and node_view() have been called.
 *
 * @param $node
 *   The node being displayed in a search result.
 *
 * @return
 *   Extra information to be displayed with search result.
 *
 * @ingroup node_api_hooks
 */
function hook_node_search_result($node) {
  $comments = db_query('SELECT comment_count FROM {node_comment_statistics} WHERE nid = :nid', array('nid' => $node->nid))->fetchField();
  return format_plural($comments, '1 comment', '@count comments');
}

/**
 * Act on a node being inserted or updated.
 *
 * This hook is invoked from node_save() before the node is saved to the
 * database.
 *
 * @param $node
 *   The node that is being inserted or updated.
 *
 * @ingroup node_api_hooks
 */
function hook_node_presave($node) {
  if ($node->nid && $node->moderate) {
    // Reset votes when node is updated:
    $node->score = 0;
    $node->users = '';
    $node->votes = 0;
  }
}

/**
 * Respond to updates to a node.
 *
 * This hook is invoked from node_save() after the node is updated in the node
 * table in the database, after the type-specific hook_update() is invoked, and
 * after field_attach_update() is called.
 *
 * @param $node
 *   The node that is being updated.
 *
 * @ingroup node_api_hooks
 */
function hook_node_update($node) {
  db_update('mytable')
    ->fields(array('extra' => $node->extra))
    ->condition('nid', $node->nid)
    ->execute();
}

/**
 * Act on a node being indexed for searching.
 *
 * This hook is invoked during search indexing, after node_load(), and after
 * the result of node_view() is added as $node->rendered to the node object.
 *
 * @param $node
 *   The node being indexed.
 *
 * @return
 *   Array of additional information to be indexed.
 *
 * @ingroup node_api_hooks
 */
function hook_node_update_index($node) {
  $text = '';
  $comments = db_query('SELECT subject, comment, format FROM {comment} WHERE nid = :nid AND status = :status', array(':nid' => $node->nid, ':status' => COMMENT_PUBLISHED));
  foreach ($comments as $comment) {
    $text .= '<h2>' . check_plain($comment->subject) . '</h2>' . check_markup($comment->comment, $comment->format, '', TRUE);
  }
  return $text;
}

/**
 * Perform node validation before a node is created or updated.
 *
 * This hook is invoked from node_validate(), after a user has has finished
 * editing the node and is previewing or submitting it. It is invoked at the
 * end of all the standard validation steps, and after the type-specific
 * hook_validate() is invoked.
 *
 * To indicate a validation error, use form_set_error().
 *
 * Note: Changes made to the $node object within your hook implementation will
 * have no effect.  The preferred method to change a node's content is to use
 * hook_node_presave() instead. If it is really necessary to change
 * the node at the validate stage, you can use form_set_value().
 *
 * @param $node
 *   The node being validated.
 * @param $form
 *   The form being used to edit the node.
 * @param $form_state
 *   The form state array.
 *
 * @ingroup node_api_hooks
 */
function hook_node_validate($node, $form, &$form_state) {
  if (isset($node->end) && isset($node->start)) {
    if ($node->start > $node->end) {
      form_set_error('time', t('An event may not end before it starts.'));
    }
  }
}

/**
 * Act on a node after validated form values have been copied to it.
 *
 * This hook is invoked when a node form is submitted with either the "Save" or
 * "Preview" button, after form values have been copied to the form state's node
 * object, but before the node is saved or previewed. It is a chance for modules
 * to adjust the node's properties from what they are simply after a copy from
 * $form_state['values']. This hook is intended for adjusting non-field-related
 * properties. See hook_field_attach_submit() for customizing field-related
 * properties.
 *
 * @param $node
 *   The node being updated in response to a form submission.
 * @param $form
 *   The form being used to edit the node.
 * @param $form_state
 *   The form state array.
 *
 * @ingroup node_api_hooks
 */
function hook_node_submit($node, $form, &$form_state) {
  // Decompose the selected menu parent option into 'menu_name' and 'plid', if
  // the form used the default parent selection widget.
  if (!empty($form_state['values']['menu']['parent'])) {
    list($node->menu['menu_name'], $node->menu['plid']) = explode(':', $form_state['values']['menu']['parent']);
  }
}

/**
 * Act on a node that is being assembled before rendering.
 *
 * The module may add elements to $node->content prior to rendering. This hook
 * will be called after hook_view(). The structure of $node->content is a
 * renderable array as expected by drupal_render().
 *
 * When $view_mode is 'rss', modules can also add extra RSS elements and
 * namespaces to $node->rss_elements and $node->rss_namespaces respectively for
 * the RSS item generated for this node.
 * For details on how this is used, see node_feed().
 *
 * @see blog_node_view()
 * @see forum_node_view()
 * @see comment_node_view()
 *
 * @param $node
 *   The node that is being assembled for rendering.
 * @param $view_mode
 *   The $view_mode parameter from node_view().
 * @param $langcode
 *   The language code used for rendering.
 *
 * @see hook_entity_view()
 *
 * @ingroup node_api_hooks
 */
function hook_node_view($node, $view_mode, $langcode) {
  $node->content['my_additional_field'] = array(
    '#markup' => $additional_field,
    '#weight' => 10,
    '#theme' => 'mymodule_my_additional_field',
  );
}

/**
 * Alter the results of node_view().
 *
 * This hook is called after the content has been assembled in a structured
 * array and may be used for doing processing which requires that the complete
 * node content structure has been built.
 *
 * If the module wishes to act on the rendered HTML of the node rather than the
 * structured content array, it may use this hook to add a #post_render
 * callback.  Alternatively, it could also implement hook_preprocess_node(). See
 * drupal_render() and theme() documentation respectively for details.
 *
 * @param $build
 *   A renderable array representing the node content.
 *
 * @see node_view()
 * @see hook_entity_view_alter()
 *
 * @ingroup node_api_hooks
 */
function hook_node_view_alter(&$build) {
  if ($build['#view_mode'] == 'full' && isset($build['an_additional_field'])) {
    // Change its weight.
    $build['an_additional_field']['#weight'] = -10;
  }

  // Add a #post_render callback to act on the rendered HTML of the node.
  $build['#post_render'][] = 'my_module_node_post_render';
}

/**
 * Define module-provided node types.
 *
 * This hook allows a module to define one or more of its own node types. For
 * example, the blog module uses it to define a blog node-type named "Blog
 * entry." The name and attributes of each desired node type are specified in
 * an array returned by the hook.
 *
 * Only module-provided node types should be defined through this hook. User-
 * provided (or 'custom') node types should be defined only in the 'node_type'
 * database table, and should be maintained by using the node_type_save() and
 * node_type_delete() functions.
 *
 * @return
 *   An array of information defining the module's node types. The array
 *   contains a sub-array for each node type, with the machine-readable type
 *   name as the key. Each sub-array has up to 10 attributes. Possible
 *   attributes:
 *   - "name": the human-readable name of the node type. Required.
 *   - "base": the base string used to construct callbacks corresponding to
 *      this node type.
 *      (i.e. if base is defined as example_foo, then example_foo_insert will
 *      be called when inserting a node of that type). This string is usually
 *      the name of the module, but not always. Required.
 *   - "description": a brief description of the node type. Required.
 *   - "help": help information shown to the user when creating a node of
 *      this type.. Optional (defaults to '').
 *   - "has_title": boolean indicating whether or not this node type has a title
 *      field. Optional (defaults to TRUE).
 *   - "title_label": the label for the title field of this content type.
 *      Optional (defaults to 'Title').
 *   - "locked": boolean indicating whether the administrator can change the
 *      machine name of this type. FALSE = changeable (not locked),
 *      TRUE = unchangeable (locked). Optional (defaults to TRUE).
 *
 * The machine-readable name of a node type should contain only letters,
 * numbers, and underscores. Underscores will be converted into hyphens for the
 * purpose of constructing URLs.
 *
 * All attributes of a node type that are defined through this hook (except for
 * 'locked') can be edited by a site administrator. This includes the
 * machine-readable name of a node type, if 'locked' is set to FALSE.
 *
 * @ingroup node_api_hooks
 */
function hook_node_info() {
  return array(
    'blog' => array(
      'name' => t('Blog entry'),
      'base' => 'blog',
      'description' => t('Use for multi-user blogs. Every user gets a personal blog.'),
    )
  );
}

/**
 * Provide additional methods of scoring for core search results for nodes.
 *
 * A node's search score is used to rank it among other nodes matched by the
 * search, with the highest-ranked nodes appearing first in the search listing.
 *
 * For example, a module allowing users to vote on content could expose an
 * option to allow search results' rankings to be influenced by the average
 * voting score of a node.
 *
 * All scoring mechanisms are provided as options to site administrators, and
 * may be tweaked based on individual sites or disabled altogether if they do
 * not make sense. Individual scoring mechanisms, if enabled, are assigned a
 * weight from 1 to 10. The weight represents the factor of magnification of
 * the ranking mechanism, with higher-weighted ranking mechanisms having more
 * influence. In order for the weight system to work, each scoring mechanism
 * must return a value between 0 and 1 for every node. That value is then
 * multiplied by the administrator-assigned weight for the ranking mechanism,
 * and then the weighted scores from all ranking mechanisms are added, which
 * brings about the same result as a weighted average.
 *
 * @return
 *   An associative array of ranking data. The keys should be strings,
 *   corresponding to the internal name of the ranking mechanism, such as
 *   'recent', or 'comments'. The values should be arrays themselves, with the
 *   following keys available:
 *   - "title": the human readable name of the ranking mechanism. Required.
 *   - "join": part of a query string to join to any additional necessary
 *     table. This is not necessary if the table required is already joined to
 *     by the base query, such as for the {node} table. Other tables should use
 *     the full table name as an alias to avoid naming collisions. Optional.
 *   - "score": part of a query string to calculate the score for the ranking
 *     mechanism based on values in the database. This does not need to be
 *     wrapped in parentheses, as it will be done automatically; it also does
 *     not need to take the weighted system into account, as it will be done
 *     automatically. It does, however, need to calculate a decimal between
 *     0 and 1; be careful not to cast the entire score to an integer by
 *     inadvertently introducing a variable argument. Required.
 *   - "arguments": if any arguments are required for the score, they can be
 *     specified in an array here.
 *
 * @ingroup node_api_hooks
 */
function hook_ranking() {
  // If voting is disabled, we can avoid returning the array, no hard feelings.
  if (variable_get('vote_node_enabled', TRUE)) {
    return array(
      'vote_average' => array(
        'title' => t('Average vote'),
        // Note that we use i.sid, the search index's search item id, rather than
        // n.nid.
        'join' => 'LEFT JOIN {vote_node_data} vote_node_data ON vote_node_data.nid = i.sid',
        // The highest possible score should be 1, and the lowest possible score,
        // always 0, should be 0.
        'score' => 'vote_node_data.average / CAST(%f AS DECIMAL)',
        // Pass in the highest possible voting score as a decimal argument.
        'arguments' => array(variable_get('vote_score_max', 5)),
      ),
    );
  }
}


/**
 * Respond to node type creation.
 *
 * This hook is invoked from node_type_save() after the node type is added
 * to the database.
 *
 * @param $info
 *   The node type object that is being created.
 */
function hook_node_type_insert($info) {
}

/**
 * Respond to node type updates.
 *
 * This hook is invoked from node_type_save() after the node type is updated
 * in the database.
 *
 * @param $info
 *   The node type object that is being updated.
 */
function hook_node_type_update($info) {
  if (!empty($info->old_type) && $info->old_type != $info->type) {
    $setting = variable_get('comment_' . $info->old_type, COMMENT_NODE_OPEN);
    variable_del('comment_' . $info->old_type);
    variable_set('comment_' . $info->type, $setting);
  }
}

/**
 * Respond to node type deletion.
 *
 * This hook is invoked from node_type_delete() after the node type is removed
 * from the database.
 *
 * @param $info
 *   The node type object that is being deleted.
 */
function hook_node_type_delete($info) {
  variable_del('comment_' . $info->type);
}

/**
 * Respond to node deletion.
 *
 * This hook is invoked only on the module that defines the node's content type
 * (use hook_node_delete() to respond to all node deletions).
 *
 * This hook is invoked from node_delete_multiple() after the node has been
 * removed from the node table in the database, before hook_node_delete() is
 * invoked, and before field_attach_delete() is called.
 *
 * @param $node
 *   The node that is being deleted.
 *
 * @ingroup node_api_hooks
 */
function hook_delete($node) {
  db_delete('mytable')
    ->condition('nid', $nid->nid)
    ->execute();
}

/**
 * Act on a node object about to be shown on the add/edit form.
 *
 * This hook is invoked only on the module that defines the node's content type
 * (use hook_node_prepare() to act on all node preparations).
 *
 * This hook is invoked from node_object_prepare() before the general
 * hook_node_prepare() is invoked.
 *
 * @param $node
 *   The node that is about to be shown on the add/edit form.
 *
 * @ingroup node_api_hooks
 */
function hook_prepare($node) {
  if ($file = file_check_upload($field_name)) {
    $file = file_save_upload($field_name, _image_filename($file->filename, NULL, TRUE));
    if ($file) {
      if (!image_get_info($file->uri)) {
        form_set_error($field_name, t('Uploaded file is not a valid image'));
        return;
      }
    }
    else {
      return;
    }
    $node->images['_original'] = $file->uri;
    _image_build_derivatives($node, TRUE);
    $node->new_file = TRUE;
  }
}

/**
 * Display a node editing form.
 *
 * This hook, implemented by node modules, is called to retrieve the form
 * that is displayed to create or edit a node. This form is displayed at path
 * node/add/[node type] or node/[node ID]/edit.
 *
 * The submit and preview buttons, administrative and display controls, and
 * sections added by other modules (such as path settings, menu settings,
 * comment settings, and fields managed by the Field UI module) are
 * displayed automatically by the node module. This hook just needs to
 * return the node title and form editing fields specific to the node type.
 *
 * For a detailed usage example, see node_example.module.
 *
 * @param $node
 *   The node being added or edited.
 * @param $form_state
 *   The form state array.
 *
 * @return
 *   An array containing the title and any custom form elements to be displayed
 *   in the node editing form.
 *
 * @ingroup node_api_hooks
 */
function hook_form($node, &$form_state) {
  $type = node_type_get_type($node);

  $form['title'] = array(
    '#type' => 'textfield',
    '#title' => check_plain($type->title_label),
    '#default_value' => !empty($node->title) ? $node->title : '',
    '#required' => TRUE, '#weight' => -5
  );

  $form['field1'] = array(
    '#type' => 'textfield',
    '#title' => t('Custom field'),
    '#default_value' => $node->field1,
    '#maxlength' => 127,
  );
  $form['selectbox'] = array(
    '#type' => 'select',
    '#title' => t('Select box'),
    '#default_value' => $node->selectbox,
    '#options' => array(
      1 => 'Option A',
      2 => 'Option B',
      3 => 'Option C',
    ),
    '#description' => t('Choose an option.'),
  );

  return $form;
}

/**
 * Respond to creation of a new node.
 *
 * This hook is invoked only on the module that defines the node's content type
 * (use hook_node_insert() to act on all node insertions).
 *
 * This hook is invoked from node_save() after the node is inserted into the
 * node table in the database, before field_attach_insert() is called, and
 * before hook_node_insert() is invoked.
 *
 * @param $node
 *   The node that is being created.
 *
 * @ingroup node_api_hooks
 */
function hook_insert($node) {
  db_insert('mytable')
    ->fields(array(
      'nid' => $node->nid,
      'extra' => $node->extra,
    ))
    ->execute();
}

/**
 * Act on nodes being loaded from the database.
 *
 * This hook is invoked only on the module that defines the node's content type
 * (use hook_node_load() to respond to all node loads).
 *
 * This hook is invoked during node loading, which is handled by entity_load(),
 * via classes NodeController and DrupalDefaultEntityController. After the node
 * information is read from the database or the entity cache, hook_load() is
 * invoked on the node's content type module, then field_attach_node_revision()
 * or field_attach_load() is called, then hook_entity_load() is invoked on all
 * implementing modules, and finally hook_node_load() is invoked on all
 * implementing modules.
 *
 * This hook should only be used to add information that is not in the node or
 * node revisions table, not to replace information that is in these tables
 * (which could interfere with the entity cache). For performance reasons,
 * information for all available nodes should be loaded in a single query where
 * possible.
 *
 * @param $nodes
 *   An array of the nodes being loaded, keyed by nid.
 *
 * For a detailed usage example, see node_example.module.
 *
 * @ingroup node_api_hooks
 */
function hook_load($nodes) {
  $result = db_query('SELECT nid, foo FROM {mytable} WHERE nid IN (:nids)', array(':nids' => array_keys($nodes)));
  foreach ($result as $record) {
    $nodes[$record->nid]->foo = $record->foo;
  }
}

/**
 * Respond to updates to a node.
 *
 * This hook is invoked only on the module that defines the node's content type
 * (use hook_node_update() to act on all node updates).
 *
 * This hook is invoked from node_save() after the node is updated in the
 * node table in the database, before field_attach_update() is called, and
 * before hook_node_update() is invoked.
 *
 * @param $node
 *   The node that is being updated.
 *
 * @ingroup node_api_hooks
 */
function hook_update($node) {
  db_update('mytable')
    ->fields(array('extra' => $node->extra))
    ->condition('nid', $node->nid)
    ->execute();
}

/**
 * Perform node validation before a node is created or updated.
 *
 * This hook is invoked only on the module that defines the node's content type
 * (use hook_node_validate() to act on all node validations).
 *
 * This hook is invoked from node_validate(), after a user has finished
 * editing the node and is previewing or submitting it. It is invoked at the end
 * of all the standard validation steps, and before hook_node_validate() is
 * invoked.
 *
 * To indicate a validation error, use form_set_error().
 *
 * Note: Changes made to the $node object within your hook implementation will
 * have no effect.  The preferred method to change a node's content is to use
 * hook_node_presave() instead.
 *
 * @param $node
 *   The node being validated.
 * @param $form
 *   The form being used to edit the node.
 * @param $form_state
 *   The form state array.
 *
 * @ingroup node_api_hooks
 */
function hook_validate($node, $form, &$form_state) {
  if (isset($node->end) && isset($node->start)) {
    if ($node->start > $node->end) {
      form_set_error('time', t('An event may not end before it starts.'));
    }
  }
}

/**
 * Display a node.
 *
 * This is a hook used by node modules. It allows a module to define a
 * custom method of displaying its nodes, usually by displaying extra
 * information particular to that node type.
 *
 * @param $node
 *   The node to be displayed, as returned by node_load().
 * @param $view_mode
 *   View mode, e.g. 'full', 'teaser', ...
 * @return
 *   $node. The passed $node parameter should be modified as necessary and
 *   returned so it can be properly presented. Nodes are prepared for display
 *   by assembling a structured array, formatted as in the Form API, in
 *   $node->content. As with Form API arrays, the #weight property can be
 *   used to control the relative positions of added elements. After this
 *   hook is invoked, node_view() calls field_attach_view() to add field
 *   views to $node->content, and then invokes hook_node_view() and
 *   hook_node_view_alter(), so if you want to affect the final
 *   view of the node, you might consider implementing one of these hooks
 *   instead.
 *
 * For a detailed usage example, see node_example.module.
 *
 * @ingroup node_api_hooks
 */
function hook_view($node, $view_mode) {
  if ($view_mode == 'full' && node_is_page($node)) {
    $breadcrumb = array();
    $breadcrumb[] = l(t('Home'), NULL);
    $breadcrumb[] = l(t('Example'), 'example');
    $breadcrumb[] = l($node->field1, 'example/' . $node->field1);
    drupal_set_breadcrumb($breadcrumb);
  }

  $node->content['myfield'] = array(
    '#markup' => theme('mymodule_myfield', $node->myfield),
    '#weight' => 1,
  );

  return $node;
}

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

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