comparison sites/all/modules/views/views.api.php @ 0:ff03f76ab3fe

initial version

+<?php
+
+/**
+ * @file
+ * Describe hooks provided by the Views module.
+ */
+
+/**
+ * @mainpage Views 3 API Manual
+ *
+ * Much of this information is actually stored in the advanced help; please
+ * check the API topic. This help will primarily be aimed at documenting
+ * classes and function calls.
+ *
+ * Topics:
+ * - @link views_lifetime The life of a view @endlink
+ * - @link views_hooks Views hooks @endlink
+ * - @link views_handlers About Views handlers @endlink
+ * - @link views_plugins About Views plugins @endlink
+ * - @link views_templates Views template files @endlink
+ * - @link views_module_handlers Views module handlers @endlink
+ */
+
+/**
+ * @defgroup views_lifetime The life of a view
+ * @{
+ * This page explains the basic cycle of a view and what processes happen.
+ *
+ * @todo.
+ * @}
+ */
+
+/**
+ * @defgroup views_handlers About Views handlers
+ * @{
+ * In Views, a handler is an object that is part of the view and is part of the
+ * query building flow.
+ *
+ * Handlers are objects; much of the time, the base handlers will work, but
+ * often you'll need to override the handler to achieve something meaningful.
+ * One typical handler override will be views_handler_filter_operator_in which
+ * allows you to have a filter select from a list of options; you'll need to
+ * override this to provide your list.
+ *
+ * Handlers have two distinct code flows; the UI flow and the view building
+ * flow.
+ *
+ * For the query flow:
+ * - handler->construct()
+ *   - Create the initial handler; at this time it is not yet attached to a
+ *     view. It is here that you can set basic defaults if needed, but there
+ *     will be no knowledge of the environment yet.
+ * - handler->set_definition()
+ *   - Set the data from hook_views_data() relevant to the handler.
+ * - handler->init()
+ *   - Attach the handler to a view, and usually provides the options from the
+ *     display.
+ * - handler->pre_query()
+ *   - Run prior to the query() stage to do early processing.
+ * - handler->query()
+ *   - Do the bulk of the work this handler needs to do to add itself to the
+ *     query.
+ *
+ * Fields, being the only handlers concerned with output, also have an extended
+ * piece of the flow:
+ *
+ * - handler->pre_render(&$values)
+ *   - Called prior to the actual rendering, this allows handlers to query for
+ *     extra data; the entire resultset is available here, and this is where
+ *     items that have "multiple values" per record can do their extra query for
+ *     all of the records available. There are several examples of this at work
+ *     in the code, see for example views_handler_field_user_roles.
+ * - handler->render()
+ *   - This does the actual work of rendering the field.
+ *
+ * Most handlers are just extensions of existing classes with a few tweaks that
+ * are specific to the field in question. For example,
+ * views_handler_filter_in_operator provides a simple mechanism to set a
+ * multiple-value list for setting filter values. Below,
+ * views_handler_filter_node_type overrides the list options, but inherits
+ * everything else.
+ *
+ * @code
+ * class views_handler_filter_node_type extends views_handler_filter_in_operator {
+ *   function get_value_options() {
+ *     if (!isset($this->value_options)) {
+ *       $this->value_title = t('Node type');
+ *       $types = node_get_types();
+ *       foreach ($types as $type => $info) {
+ *         $options[$type] = $info-&gt;name;
+ *       }
+ *       $this->value_options = $options;
+ *     }
+ *   }
+ * }
+ * @endcode
+ *
+ * Handlers are stored in their own files and loaded on demand. Like all other
+ * module files, they must first be registered through the module's info file.
+ * For example:
+ *
+ * @code
+ * name = Example module
+ * description = "Gives an example of a module."
+ * core = 7.x
+ * files[] = example.module
+ * files[] = example.install
+ *
+ * ; Views handlers
+ * files[] = includes/views/handlers/example_handler_argument_string.inc
+ * @endcode
+ *
+ * The best place to learn more about handlers and how they work is to explore
+ * @link views_handlers Views' handlers @endlink and use existing handlers as a
+ * guide and a model. Understanding how views_handler and its child classes work
+ * is handy but you can do a lot just following these models. You can also
+ * explore the views module directory, particularly node.views.inc.
+ *
+ * Please note that while all handler names in views are prefixed with views_,
+ * you should use your own module's name to prefix your handler names in order
+ * to ensure namespace safety. Note that the basic pattern for handler naming
+ * goes like this:
+ *
+ * [module]_handler_[type]_[tablename]_[fieldname].
+ *
+ * Sometimes table and fieldname are not appropriate, but something that
+ * resembles what the table/field would be can be used.
+ *
+ * See also:
+ * - @link views_field_handlers Views field handlers @endlink
+ * - @link views_sort_handlers Views sort handlers @endlink
+ * - @link views_filter_handlers Views filter handlers @endlink
+ * - @link views_argument_handlers Views argument handlers @endlink
+ * - @link views_relationship_handlers Views relationship handlers @endlink
+ * - @link views_area_handlers Views area handlers @endlink
+ * @}
+ */
+
+/**
+ * @defgroup views_plugins About Views plugins
+ *
+ * In Views, a plugin is a bit like a handler, but plugins are not directly
+ * responsible for building the query. Instead, they are objects that are used
+ * to display the view or make other modifications.
+ *
+ * There are 10 types of plugins in Views:
+ * - Display: Display plugins are responsible for controlling *where* a view
+ *   lives; that is, how they are being exposed to other parts of Drupal. Page
+ *   and block are the most common displays, as well as the ubiquitous 'master'
+ *   (or 'default') display.
+ * - Style: Style plugins control how a view is displayed. For the most part
+ *   they are object wrappers around theme templates. Styles could for example
+ *   be HTML lists or tables.
+ * - Row style: Row styles handle each individual record from the main view
+ *   table. The two included by default render the entire entity (nodes only),
+ *   or selected fields.
+ * - Argument default: Argument default plugins allow pluggable ways of
+ *   providing default values for contextual filters (previously 'arguments').
+ *   This is useful for blocks and other display types lacking a natural
+ *   argument input. Examples are plugins to extract node and user IDs from the
+ *   URL.
+ * - Argument validator: Validator plugins can ensure arguments are valid, and
+ *   even do transformations on the arguments. They can also provide replacement
+ *   patterns for the view title. For example, the 'content' validator
+ *   verifies verifies that the argument value corresponds to a node, loads
+ *   that node and provides the node title as a replacement pattern.
+ * - Access: Access plugins are responsible for controlling access to the view.
+ *   Views includes plugins for checking user roles and individual permissions.
+ * - Query: Query plugins generate and execute a query, so they can be seen as
+ *   a data backend. The default implementation is using SQL. There are
+ *   contributed modules reading data from other sources, see for example the
+ *   Views XML Backend module.
+ * - Cache: Cache plugins control the storage and loading of caches. Currently
+ *   they can do both result and render caching, but maybe one day cache the
+ *   generated query.
+ * - Pager plugins: Pager plugins take care of everything regarding pagers.
+ *   From getting and setting the total amount of items to render the pager and
+ *   setting the global pager arrays.
+ * - Exposed form plugins: Exposed form plugins are responsible for building,
+ *   rendering and controlling exposed forms. They can expose new parts of the
+ *   view to the user and more.
+ * - Localization plugins: Localization plugins take care how the view options
+ *   are translated. There are example implementations for t(), 'no
+ *   translation' and i18n.
+ * - Display extenders: Display extender plugins allow scaling of views options
+ *   horizontally. This means that you can add options and do stuff on all
+ *   views displays. One theoretical example is metatags for views.
+ *
+ * Plugins are registered by implementing hook_views_plugins() in your
+ * modulename.views.inc file and returning an array of data.
+ * For examples please look at views_views_plugins() in
+ * views/includes/plugins.inc as it has examples for all of them.
+ *
+ * Similar to handlers, make sure that you add your plugin files to the
+ * module.info file.
+ *
+ * The array defining plugins will look something like this:
+ * @code
+ * return array(
+ *   'display' => array(
+ *     // ... list of display plugins,
+ *    ),
+ *   'style' => array(
+ *     // ... list of style plugins,
+ *    ),
+ *   'row' => array(
+ *     // ... list of row style plugins,
+ *    ),
+ *   'argument default' => array(
+ *     // ... list of argument default plugins,
+ *    ),
+ *   'argument validator' => array(
+ *     // ... list of argument validator plugins,
+ *    ),
+ *    'access' => array(
+ *     // ... list of access plugins,
+ *    ),
+ *    'query' => array(
+ *      // ... list of query plugins,
+ *     ),,
+ *    'cache' => array(
+ *      // ... list of cache plugins,
+ *     ),,
+ *    'pager' => array(
+ *      // ... list of pager plugins,
+ *     ),,
+ *    'exposed_form' => array(
+ *      // ... list of exposed_form plugins,
+ *     ),,
+ *    'localization' => array(
+ *      // ... list of localization plugins,
+ *     ),
+ *    'display_extender' => array(
+ *      // ... list of display extender plugins,
+ *     ),
+ * );
+ * @endcode
+ *
+ * Each plugin will be registered with an identifier for the plugin, plus a
+ * fairly lengthy list of items that can define how and where the plugin is
+ * used. Here is an example of a row style plugin from Views core:
+ * @code
+ *     'node' => array(
+ *       'title' => t('Node'),
+ *       'help' => t('Display the node with standard node view.'),
+ *       'handler' => 'views_plugin_row_node_view',
+ *       'path' => drupal_get_path('module', 'views') . '/modules/node', // not necessary for most modules
+ *       'theme' => 'views_view_row_node',
+ *       'base' => array('node'), // only works with 'node' as base.
+ *       'uses options' => TRUE,
+ *       'type' => 'normal',
+ *     ),
+ * @endcode
+ *
+ * Of particular interest is the *path* directive, which works a little
+ * differently from handler registration; each plugin must define its own path,
+ * rather than relying on a global info for the paths. For example:
+ * @code
+ *    'feed' => array(
+ *      'title' => t('Feed'),
+ *      'help' => t('Display the view as a feed, such as an RSS feed.'),
+ *      'handler' => 'views_plugin_display_feed',
+ *      'uses hook menu' => TRUE,
+ *      'use ajax' => FALSE,
+ *      'use pager' => FALSE,
+ *      'accept attachments' => FALSE,
+ *      'admin' => t('Feed'),
+ *      'help topic' => 'display-feed',
+ *     ),
+ * @endcode
+ *
+ * Please be sure to prefix your plugin identifiers with your module name to
+ * ensure namespace safety; after all, two different modules could try to
+ * implement the 'grid2' plugin, and that would cause one plugin to completely
+ * fail.
+ *
+ * @todo Finish this document.
+ *
+ * See also:
+ * - @link views_display_plugins Views display plugins @endlink
+ * - @link views_style_plugins Views style plugins @endlink
+ * - @link views_row_plugins Views row plugins @endlink
+ */
+
+/**
+ * @defgroup views_hooks Views hooks
+ * @{
+ * Hooks that can be implemented by other modules in order to implement the
+ * Views API.
+ */
+
+/**
+ * Describes data tables (or the equivalent) to Views.
+ *
+ * This hook should be placed in MODULENAME.views.inc and it will be
+ * auto-loaded. MODULENAME.views.inc must be in the directory specified by the
+ * 'path' key returned by MODULENAME_views_api(), or the same directory as the
+ * .module file, if 'path' is unspecified.
+ *
+ * @return
+ *   An associative array describing the data structure. Primary key is the
+ *   name used internally by Views for the table(s) – usually the actual table
+ *   name. The values for the key entries are described in detail below.
+ */
+function hook_views_data() {
+  // This example describes how to write hook_views_data() for the following
+  // table:
+  //
+  // CREATE TABLE example_table (
+  //   nid INT(11) NOT NULL         COMMENT 'Primary key; refers to {node}.nid.',
+  //   plain_text_field VARCHAR(32) COMMENT 'Just a plain text field.',
+  //   numeric_field INT(11)        COMMENT 'Just a numeric field.',
+  //   boolean_field INT(1)         COMMENT 'Just an on/off field.',
+  //   timestamp_field INT(8)       COMMENT 'Just a timestamp field.',
+  //   PRIMARY KEY(nid)
+  // );
+
+  // First, the entry $data['example_table']['table'] describes properties of
+  // the actual table – not its content.
+
+  // The 'group' index will be used as a prefix in the UI for any of this
+  // table's fields, sort criteria, etc. so it's easy to tell where they came
+  // from.
+  $data['example_table']['table']['group'] = t('Example table');
+
+  // Define this as a base table – a table that can be described in itself by
+  // views (and not just being brought in as a relationship). In reality this
+  // is not very useful for this table, as it isn't really a distinct object of
+  // its own, but it makes a good example.
+  $data['example_table']['table']['base'] = array(
+    'field' => 'nid', // This is the identifier field for the view.
+    'title' => t('Example table'),
+    'help' => t('Example table contains example content and can be related to nodes.'),
+    'weight' => -10,
+  );
+
+  // This table references the {node} table. The declaration below creates an
+  // 'implicit' relationship to the node table, so that when 'node' is the base
+  // table, the fields are automatically available.
+  $data['example_table']['table']['join'] = array(
+    // Index this array by the table name to which this table refers.
+    // 'left_field' is the primary key in the referenced table.
+    // 'field' is the foreign key in this table.
+    'node' => array(
+      'left_field' => 'nid',
+      'field' => 'nid',
+    ),
+  );
+
+  // Next, describe each of the individual fields in this table to Views. This
+  // is done by describing $data['example_table']['FIELD_NAME']. This part of
+  // the array may then have further entries:
+  //   - title: The label for the table field, as presented in Views.
+  //   - help: The description text for the table field.
+  //   - relationship: A description of any relationship handler for the table
+  //     field.
+  //   - field: A description of any field handler for the table field.
+  //   - sort: A description of any sort handler for the table field.
+  //   - filter: A description of any filter handler for the table field.
+  //   - argument: A description of any argument handler for the table field.
+  //   - area: A description of any handler for adding content to header,
+  //     footer or as no result behaviour.
+  //
+  // The handler descriptions are described with examples below.
+
+  // Node ID table field.
+  $data['example_table']['nid'] = array(
+    'title' => t('Example content'),
+    'help' => t('Some example content that references a node.'),
+    // Define a relationship to the {node} table, so example_table views can
+    // add a relationship to nodes. If you want to define a relationship the
+    // other direction, use hook_views_data_alter(), or use the 'implicit' join
+    // method described above.
+    'relationship' => array(
+      'base' => 'node', // The name of the table to join with.
+      'base field' => 'nid', // The name of the field on the joined table.
+      // 'field' => 'nid' -- see hook_views_data_alter(); not needed here.
+      'handler' => 'views_handler_relationship',
+      'label' => t('Default label for the relationship'),
+      'title' => t('Title shown when adding the relationship'),
+      'help' => t('More information on this relationship'),
+    ),
+  );
+
+  // Example plain text field.
+  $data['example_table']['plain_text_field'] = array(
+    'title' => t('Plain text field'),
+    'help' => t('Just a plain text field.'),
+    'field' => array(
+      'handler' => 'views_handler_field',
+      'click sortable' => TRUE, // This is use by the table display plugin.
+    ),
+    'sort' => array(
+      'handler' => 'views_handler_sort',
+    ),
+    'filter' => array(
+      'handler' => 'views_handler_filter_string',
+    ),
+    'argument' => array(
+      'handler' => 'views_handler_argument_string',
+    ),
+  );
+
+  // Example numeric text field.
+  $data['example_table']['numeric_field'] = array(
+    'title' => t('Numeric field'),
+    'help' => t('Just a numeric field.'),
+    'field' => array(
+      'handler' => 'views_handler_field_numeric',
+      'click sortable' => TRUE,
+     ),
+    'filter' => array(
+      'handler' => 'views_handler_filter_numeric',
+    ),
+    'sort' => array(
+      'handler' => 'views_handler_sort',
+    ),
+  );
+
+  // Example boolean field.
+  $data['example_table']['boolean_field'] = array(
+    'title' => t('Boolean field'),
+    'help' => t('Just an on/off field.'),
+    'field' => array(
+      'handler' => 'views_handler_field_boolean',
+      'click sortable' => TRUE,
+    ),
+    'filter' => array(
+      'handler' => 'views_handler_filter_boolean_operator',
+      // Note that you can override the field-wide label:
+      'label' => t('Published'),
+      // This setting is used by the boolean filter handler, as possible option.
+      'type' => 'yes-no',
+      // use boolean_field = 1 instead of boolean_field <> 0 in WHERE statment.
+      'use equal' => TRUE,
+    ),
+    'sort' => array(
+      'handler' => 'views_handler_sort',
+    ),
+  );
+
+  // Example timestamp field.
+  $data['example_table']['timestamp_field'] = array(
+    'title' => t('Timestamp field'),
+    'help' => t('Just a timestamp field.'),
+    'field' => array(
+      'handler' => 'views_handler_field_date',
+      'click sortable' => TRUE,
+    ),
+    'sort' => array(
+      'handler' => 'views_handler_sort_date',
+    ),
+    'filter' => array(
+      'handler' => 'views_handler_filter_date',
+    ),
+  );
+
+  return $data;
+}
+
+/**
+ * Alter table structure.
+ *
+ * You can add/edit/remove existing tables defined by hook_views_data().
+ *
+ * This hook should be placed in MODULENAME.views.inc and it will be
+ * auto-loaded. MODULENAME.views.inc must be in the directory specified by the
+ * 'path' key returned by MODULENAME_views_api(), or the same directory as the
+ * .module file, if 'path' is unspecified.
+ *
+ * @param $data
+ *   An array of all Views data, passed by reference. See hook_views_data() for
+ *   structure.
+ *
+ * @see hook_views_data()
+ */
+function hook_views_data_alter(&$data) {
+  // This example alters the title of the node:nid field in the Views UI.
+  $data['node']['nid']['title'] = t('Node-Nid');
+
+  // This example adds an example field to the users table.
+  $data['users']['example_field'] = array(
+    'title' => t('Example field'),
+    'help' => t('Some example content that references a user'),
+    'field' => array(
+      'handler' => 'modulename_handler_field_example_field',
+    ),
+  );
+
+  // This example changes the handler of the node title field.
+  // In this handler you could do stuff, like preview of the node when clicking
+  // the node title.
+  $data['node']['title']['field']['handler'] = 'modulename_handler_field_node_title';
+
+  // This example adds a relationship to table {foo}, so that 'foo' views can
+  // add this table using a relationship. Because we don't want to write over
+  // the primary key field definition for the {foo}.fid field, we use a dummy
+  // field name as the key.
+  $data['foo']['dummy_name'] = array(
+    'title' => t('Example relationship'),
+    'help' => t('Example help'),
+    'relationship' => array(
+      'base' => 'example_table', // Table we're joining to.
+      'base field' => 'eid', // Field on the joined table.
+      'field' => 'fid', // Real field name on the 'foo' table.
+      'handler' => 'views_handler_relationship',
+      'label' => t('Default label for relationship'),
+      'title' => t('Title seen when adding relationship'),
+      'help' => t('More information about relationship.'),
+    ),
+  );
+
+  // Note that the $data array is not returned – it is modified by reference.
+}
+
+
+/**
+ * Describes plugins defined by the module.
+ *
+ * This hook should be placed in MODULENAME.views.inc and it will be
+ * auto-loaded. MODULENAME.views.inc must be in the directory specified by the
+ * 'path' key returned by MODULENAME_views_api(), or the same directory as the
+ * .module file, if 'path' is unspecified. All plugin files need to be
+ * referenced in MODULENAME.info with the files[] directive.
+ *
+ * @return
+ *   An array on the form $plugins['PLUGIN TYPE']['PLUGIN NAME']. The plugin
+ *   must be one of row, display, display_extender, style, argument default,
+ *   argument validator, access, query, cache, pager, exposed_form or
+ *   localization. The plugin name should be prefixed with your module name.
+ *   The value for each entry is an associateive array that may contain the
+ *   following entries:
+ *   - Used by all plugin types:
+ *     - title (required): The name of the plugin, as shown in Views. Wrap in
+ *       t().
+ *     - handler (required): The name of the file containing the class
+ *       describing the handler, which must also be the name of the handler's
+ *       class.
+ *     - path: Path to the handler. Only required if the handler is not placed
+ *       in the same folder as the .module file or in the subfolder 'views'.
+ *     - parent: The name of the plugin this plugin extends. Since Drupal 7 this
+ *       is no longer required, but may still be useful from a code readability
+ *       perspective.
+ *     - no ui: Set to TRUE to denote that the plugin doesn't appear to be
+ *       selectable in the ui, though on the api side they still exists.
+ *     - uses options: Set to TRUE to denote that the plugin has an additional
+ *       options form.
+ *     - help: A short help text, wrapped in t() used as description on the plugin settings form.
+ *     - help topic: The name of an entry by advanced help for the plugin.
+ *     - theme: The name of a theme suggestion to use for the display.
+ *     - js: An array with paths to js files that should be included for the
+ *       display. Note that the path should be relative Drupal root, not module
+ *       root.
+ *     - type: Each plugin can specify a type parameter to group certain
+ *       plugins together. For example all row plugins related to feeds are
+ *       grouped together, because a rss style plugin only accepts feed row
+ *       plugins.
+ *
+ *   - Used by display plugins:
+ *     - admin: The administrative name of the display, as displayed on the
+ *       Views overview and also used as default name for new displays. Wrap in
+ *       t().
+ *     - no remove: Set to TRUE to make the display non-removable. (Basically
+ *       only used for the master/default display.)
+ *     - use ajax: Set to TRUE to allow AJAX loads in the display. If it's
+ *       disabled there will be no ajax option in the ui.
+ *     - use pager: Set to TRUE to allow paging in the display.
+ *     - use more: Set to TRUE to allow the 'use more' setting in the display.
+ *     - accept attachments: Set to TRUE to allow attachment displays to be
+ *       attached to this display type.
+ *     - contextual links locations: An array with places where contextual links
+ *       should be added. Can for example be 'page' or 'block'. If you don't
+ *       specify it there will be contextual links around the rendered view. If
+ *       this is not set or regions have been specified, views will display an
+ *       option to 'hide contextual links'. Use an empty array if you do not want
+ *       this.
+ *     - uses hook menu: Set to TRUE to have the display included by
+ *       views_menu_alter(). views_menu_alter executes then execute_hook_menu
+ *       on the display object.
+ *     - uses hook block: Set to TRUE to have the display included by
+ *       views_block_info().
+ *     - theme: The name of a theme suggestion to use for the display.
+ *     - js: An array with paths to js files that should be included for the
+ *       display. Note that the path should be relative Drupal root, not module
+ *       root.
+ *
+ *   - Used by style plugins:
+ *     - uses row plugin: Set to TRUE to allow row plugins for this style.
+ *     - uses row class: Set to TRUE to allow the CSS class settings for rows.
+ *     - uses fields: Set to TRUE to have the style plugin accept field
+ *       handlers.
+ *     - uses grouping: Set to TRUE to allow the grouping settings for rows.
+ *     - even empty: May have the value 'even empty' to tell Views that the style
+ *       should be rendered even if there are no results.
+ *
+ *   - Used by row plugins:
+ *     - uses fields: Set to TRUE to have the row plugin accept field handlers.
+ */
+function hook_views_plugins() {
+  $plugins = array();
+  $plugins['argument validator'] = array(
+    'taxonomy_term' => array(
+      'title' => t('Taxonomy term'),
+      'handler' => 'views_plugin_argument_validate_taxonomy_term',
+      // Declaring path explicitly not necessary for most modules.
+      'path' => drupal_get_path('module', 'views') . '/modules/taxonomy',
+    ),
+  );
+
+  return array(
+    'module' => 'views', // This just tells our themes are elsewhere.
+    'argument validator' => array(
+      'taxonomy_term' => array(
+        'title' => t('Taxonomy term'),
+        'handler' => 'views_plugin_argument_validate_taxonomy_term',
+        'path' => drupal_get_path('module', 'views') . '/modules/taxonomy', // not necessary for most modules
+      ),
+    ),
+    'argument default' => array(
+      'taxonomy_tid' => array(
+        'title' => t('Taxonomy term ID from URL'),
+        'handler' => 'views_plugin_argument_default_taxonomy_tid',
+        'path' => drupal_get_path('module', 'views') . '/modules/taxonomy',
+        'parent' => 'fixed',
+      ),
+    ),
+  );
+}
+
+/**
+ * Alter existing plugins data, defined by modules.
+ *
+ * @see hook_views_plugins()
+ */
+function hook_views_plugins_alter(&$plugins) {
+  // Add apachesolr to the base of the node row plugin.
+  $plugins['row']['node']['base'][] = 'apachesolr';
+}
+
+/**
+ * Register View API information.
+ *
+ * This is required for your module to have its include files loaded; for
+ * example, when implementing hook_views_default_views().
+ *
+ * @return
+ *   An array with the following possible keys:
+ *   - api: (required) The version of the Views API the module implements.
+ *   - path: (optional) If includes are stored somewhere other than within the
+ *     root module directory, specify its path here.
+ *   - template path: (optional) A path where the module has stored it's views
+ *     template files. When you have specificed this key views automatically
+ *     uses the template files for the views. You can use the same naming
+ *     conventions like for normal views template files.
+ */
+function hook_views_api() {
+  return array(
+    'api' => 3,
+    'path' => drupal_get_path('module', 'example') . '/includes/views',
+    'template path' => drupal_get_path('module', 'example') . '/themes',
+  );
+}
+
+/**
+ * This hook allows modules to provide their own views which can either be used
+ * as-is or as a "starter" for users to build from.
+ *
+ * This hook should be placed in MODULENAME.views_default.inc and it will be
+ * auto-loaded. MODULENAME.views_default.inc must be in the directory specified
+ * by the 'path' key returned by MODULENAME_views_api(), or the same directory
+ * as the .module file, if 'path' is unspecified.
+ *
+ * The $view->disabled boolean flag indicates whether the View should be
+ * enabled (FALSE) or disabled (TRUE) by default.
+ *
+ * @return
+ *   An associative array containing the structures of views, as generated from
+ *   the Export tab, keyed by the view name. A best practice is to go through
+ *   and add t() to all title and label strings, with the exception of menu
+ *   strings.
+ */
+function hook_views_default_views() {
+  // Begin copy and paste of output from the Export tab of a view.
+  $view = new view;
+  $view->name = 'frontpage';
+  $view->description = 'Emulates the default Drupal front page; you may set the default home page path to this view to make it your front page.';
+  $view->tag = 'default';
+  $view->base_table = 'node';
+  $view->human_name = 'Front page';
+  $view->core = 0;
+  $view->api_version = '3.0';
+  $view->disabled = FALSE; /* Edit this to true to make a default view disabled initially */
+
+  /* Display: Master */
+  $handler = $view->new_display('default', 'Master', 'default');
+  $handler->display->display_options['access']['type'] = 'none';
+  $handler->display->display_options['cache']['type'] = 'none';
+  $handler->display->display_options['query']['type'] = 'views_query';
+  $handler->display->display_options['query']['options']['query_comment'] = FALSE;
+  $handler->display->display_options['exposed_form']['type'] = 'basic';
+  $handler->display->display_options['pager']['type'] = 'full';
+  $handler->display->display_options['style_plugin'] = 'default';
+  $handler->display->display_options['row_plugin'] = 'node';
+  /* Sort criterion: Content: Sticky */
+  $handler->display->display_options['sorts']['sticky']['id'] = 'sticky';
+  $handler->display->display_options['sorts']['sticky']['table'] = 'node';
+  $handler->display->display_options['sorts']['sticky']['field'] = 'sticky';
+  $handler->display->display_options['sorts']['sticky']['order'] = 'DESC';
+  /* Sort criterion: Content: Post date */
+  $handler->display->display_options['sorts']['created']['id'] = 'created';
+  $handler->display->display_options['sorts']['created']['table'] = 'node';
+  $handler->display->display_options['sorts']['created']['field'] = 'created';
+  $handler->display->display_options['sorts']['created']['order'] = 'DESC';
+  /* Filter criterion: Content: Promoted to front page */
+  $handler->display->display_options['filters']['promote']['id'] = 'promote';
+  $handler->display->display_options['filters']['promote']['table'] = 'node';
+  $handler->display->display_options['filters']['promote']['field'] = 'promote';
+  $handler->display->display_options['filters']['promote']['value'] = '1';
+  $handler->display->display_options['filters']['promote']['group'] = 0;
+  $handler->display->display_options['filters']['promote']['expose']['operator'] = FALSE;
+  /* Filter criterion: Content: Published */
+  $handler->display->display_options['filters']['status']['id'] = 'status';
+  $handler->display->display_options['filters']['status']['table'] = 'node';
+  $handler->display->display_options['filters']['status']['field'] = 'status';
+  $handler->display->display_options['filters']['status']['value'] = '1';
+  $handler->display->display_options['filters']['status']['group'] = 0;
+  $handler->display->display_options['filters']['status']['expose']['operator'] = FALSE;
+
+  /* Display: Page */
+  $handler = $view->new_display('page', 'Page', 'page');
+  $handler->display->display_options['path'] = 'frontpage';
+
+  /* Display: Feed */
+  $handler = $view->new_display('feed', 'Feed', 'feed');
+  $handler->display->display_options['defaults']['title'] = FALSE;
+  $handler->display->display_options['title'] = 'Front page feed';
+  $handler->display->display_options['pager']['type'] = 'some';
+  $handler->display->display_options['style_plugin'] = 'rss';
+  $handler->display->display_options['row_plugin'] = 'node_rss';
+  $handler->display->display_options['path'] = 'rss.xml';
+  $handler->display->display_options['displays'] = array(
+    'default' => 'default',
+    'page' => 'page',
+  );
+  $handler->display->display_options['sitename_title'] = '1';
+
+  // (Export ends here.)
+
+  // Add view to list of views to provide.
+  $views[$view->name] = $view;
+
+  // ...Repeat all of the above for each view the module should provide.
+
+  // At the end, return array of default views.
+  return $views;
+}
+
+/**
+ * Alter default views defined by other modules.
+ *
+ * This hook is called right before all default views are cached to the
+ * database. It takes a keyed array of views by reference.
+ *
+ * Example usage to add a field to a view:
+ * @code
+ *   $handler =& $view->display['DISPLAY_ID']->handler;
+ *   // Add the user name field to the view.
+ *   $handler->display->display_options['fields']['name']['id'] = 'name';
+ *   $handler->display->display_options['fields']['name']['table'] = 'users';
+ *   $handler->display->display_options['fields']['name']['field'] = 'name';
+ *   $handler->display->display_options['fields']['name']['label'] = 'Author';
+ *   $handler->display->display_options['fields']['name']['link_to_user'] = 1;
+ * @endcode
+ */
+function hook_views_default_views_alter(&$views) {
+  if (isset($views['taxonomy_term'])) {
+    $views['taxonomy_term']->display['default']->display_options['title'] = 'Categories';
+  }
+}
+
+/**
+ * Performs replacements in the query before being performed.
+ *
+ * @param $view
+ *   The View being executed.
+ * @return
+ *   An array with keys being the strings to replace, and the values the strings
+ *   to replace them with. The strings to replace are ofted surrounded with
+ *   '***', as illustrated in the example implementation.
+ */
+function hook_views_query_substitutions($view) {
+  // Example from views_views_query_substitutions().
+  global $language_content;
+  return array(
+    '***CURRENT_VERSION***' => VERSION,
+    '***CURRENT_TIME***' => REQUEST_TIME,
+    '***CURRENT_LANGUAGE***' => $language_content->language,
+    '***DEFAULT_LANGUAGE***' => language_default('language'),
+  );
+}
+
+/**
+ * This hook is called to get a list of placeholders and their substitutions,
+ * used when preprocessing a View with form elements.
+ *
+ * @return
+ *   An array with keys being the strings to replace, and the values the strings
+ *   to replace them with.
+ */
+function hook_views_form_substitutions() {
+  return array(
+    '<!--views-form-example-substitutions-->' => 'Example Substitution',
+  );
+}
+
+/**
+ * Allows altering a view at the very beginning of views processing, before
+ * anything is done.
+ *
+ * Adding output to the view can be accomplished by placing text on
+ * $view->attachment_before and $view->attachment_after.
+ * @param $view
+ *   The view object about to be processed.
+ * @param $display_id
+ *   The machine name of the active display.
+ * @param $args
+ *   An array of arguments passed into the view.
+ */
+function hook_views_pre_view(&$view, &$display_id, &$args) {
+  // Change the display if the acting user has 'administer site configuration'
+  // permission, to display something radically different.
+  // (Note that this is not necessarily the best way to solve that task. Feel
+  // free to contribute another example!)
+  if (
+    $view->name == 'my_special_view' &&
+    user_access('administer site configuration') &&
+    $display_id == 'public_display'
+  ) {
+    $display_id = 'private_display';
+  }
+}
+
+/**
+ * This hook is called right before the build process, but after displays
+ * are attached and the display performs its pre_execute phase.
+ *
+ * Adding output to the view can be accomplished by placing text on
+ * $view->attachment_before and $view->attachment_after.
+ * @param $view
+ *   The view object about to be processed.
+ */
+function hook_views_pre_build(&$view) {
+  // Because of some unexplicable business logic, we should remove all
+  // attachments from all views on Mondays.
+  // (This alter could be done later in the execution process as well.)
+  if (date('D') == 'Mon') {
+    unset($view->attachment_before);
+    unset($view->attachment_after);
+  }
+}
+
+/**
+ * This hook is called right after the build process. The query is now fully
+ * built, but it has not yet been run through db_rewrite_sql.
+ *
+ * Adding output to the view can be accomplished by placing text on
+ * $view->attachment_before and $view->attachment_after.
+ * @param $view
+ *   The view object about to be processed.
+ */
+function hook_views_post_build(&$view) {
+  // If the exposed field 'type' is set, hide the column containing the content
+  // type. (Note that this is a solution for a particular view, and makes
+  // assumptions about both exposed filter settings and the fields in the view.
+  // Also note that this alter could be done at any point before the view being
+  // rendered.)
+  if ($view->name == 'my_view' && isset($view->exposed_raw_input['type']) && $view->exposed_raw_input['type'] != 'All') {
+    // 'Type' should be interpreted as content type.
+    if (isset($view->field['type'])) {
+      $view->field['type']->options['exclude'] = TRUE;
+    }
+  }
+}
+
+/**
+ * This hook is called right before the execute process. The query is now fully
+ * built, but it has not yet been run through db_rewrite_sql.
+ *
+ * Adding output to the view can be accomplished by placing text on
+ * $view->attachment_before and $view->attachment_after.
+ * @param $view
+ *   The view object about to be processed.
+ */
+function hook_views_pre_execute(&$view) {
+  // Whenever a view queries more than two tables, show a message that notifies
+  // view administrators that the query might be heavy.
+  // (This action could be performed later in the execution process, but not
+  // earlier.)
+  if (count($view->query->tables) > 2 && user_access('administer views')) {
+    drupal_set_message(t('The view %view may be heavy to execute.', array('%view' => $view->name)), 'warning');
+  }
+}
+
+/**
+ * This hook is called right after the execute process. The query has
+ * been executed, but the pre_render() phase has not yet happened for
+ * handlers.
+ *
+ * Adding output to the view can be accomplished by placing text on
+ * $view->attachment_before and $view->attachment_after. Altering the
+ * content can be achieved by editing the items of $view->result.
+ * @param $view
+ *   The view object about to be processed.
+ */
+function hook_views_post_execute(&$view) {
+  // If there are more than 100 results, show a message that encourages the user
+  // to change the filter settings.
+  // (This action could be performed later in the execution process, but not
+  // earlier.)
+  if ($view->total_rows > 100) {
+    drupal_set_message(t('You have more than 100 hits. Use the filter settings to narrow down your list.'));
+  }
+}
+
+/**
+ * This hook is called right before the render process. The query has been
+ * executed, and the pre_render() phase has already happened for handlers, so
+ * all data should be available.
+ *
+ * Adding output to the view can be accomplished by placing text on
+ * $view->attachment_before and $view->attachment_after. Altering the content
+ * can be achieved by editing the items of $view->result.
+ *
+ * This hook can be utilized by themes.
+ * @param $view
+ *   The view object about to be processed.
+ */
+function hook_views_pre_render(&$view) {
+  // Scramble the order of the rows shown on this result page.
+  // Note that this could be done earlier, but not later in the view execution
+  // process.
+  shuffle($view->result);
+}
+
+/**
+ * Post process any rendered data.
+ *
+ * This can be valuable to be able to cache a view and still have some level of
+ * dynamic output. In an ideal world, the actual output will include HTML
+ * comment based tokens, and then the post process can replace those tokens.
+ *
+ * Example usage. If it is known that the view is a node view and that the
+ * primary field will be a nid, you can do something like this:
+ *
+ * <!--post-FIELD-NID-->
+ *
+ * And then in the post render, create an array with the text that should
+ * go there:
+ *
+ * strtr($output, array('<!--post-FIELD-1-->' => 'output for FIELD of nid 1');
+ *
+ * All of the cached result data will be available in $view->result, as well,
+ * so all ids used in the query should be discoverable.
+ *
+ * This hook can be utilized by themes.
+ * @param $view
+ *   The view object about to be processed.
+ * @param $output
+ *   A flat string with the rendered output of the view.
+ * @param $cache
+ *   The cache settings.
+ */
+function hook_views_post_render(&$view, &$output, &$cache) {
+  // When using full pager, disable any time-based caching if there are less
+  // then 10 results.
+  if ($view->query->pager instanceof views_plugin_pager_full && $cache->options['type'] == 'time' && count($view->result) < 10) {
+    $cache['options']['results_lifespan'] = 0;
+    $cache['options']['output_lifespan'] = 0;
+  }
+}
+
+/**
+ * Alter the query before executing the query.
+ *
+ * This hook should be placed in MODULENAME.views.inc and it will be
+ * auto-loaded. MODULENAME.views.inc must be in the directory specified by the
+ * 'path' key returned by MODULENAME_views_api(), or the same directory as the
+ * .module file, if 'path' is unspecified.
+ *
+ * @param $view
+ *   The view object about to be processed.
+ * @param $query
+ *   An object describing the query.
+ * @see hook_views_query_substitutions()
+ */
+function hook_views_query_alter(&$view, &$query) {
+  // (Example assuming a view with an exposed filter on node title.)
+  // If the input for the title filter is a positive integer, filter against
+  // node ID instead of node title.
+  if ($view->name == 'my_view' && is_numeric($view->exposed_raw_input['title']) && $view->exposed_raw_input['title'] > 0) {
+    // Traverse through the 'where' part of the query.
+    foreach ($query->where as &$condition_group) {
+      foreach ($condition_group['conditions'] as &$condition) {
+        // If this is the part of the query filtering on title, chang the
+        // condition to filter on node ID.
+        if ($condition['field'] == 'node.title') {
+          $condition = array(
+            'field' => 'node.nid',
+            'value' => $view->exposed_raw_input['title'],
+            'operator' => '=',
+          );
+        }
+      }
+    }
+  }
+}
+
+/**
+ * Alter the information box that (optionally) appears with a view preview,
+ * including query and performance statistics.
+ *
+ * This hook should be placed in MODULENAME.views.inc and it will be
+ * auto-loaded. MODULENAME.views.inc must be in the directory specified by the
+ * 'path' key returned by MODULENAME_views_api(), or the same directory as the
+ * .module file, if 'path' is unspecified.
+ *
+ * Warning: $view is not a reference in PHP4 and cannot be modified here. But it
+ * IS a reference in PHP5, and can be modified. Please be careful with it.
+ *
+ * @param $rows
+ *   An associative array with two keys:
+ *   - query: An array of rows suitable for theme('table'), containing
+ *     information about the query and the display title and path.
+ *   - statistics: An array of rows suitable for theme('table'), containing
+ *     performance statistics.
+ * @param $view
+ *   The view object.
+ * @see theme_table()
+ */
+function hook_views_preview_info_alter(&$rows, $view) {
+  // Adds information about the tables being queried by the view to the query
+  // part of the info box.
+  $rows['query'][] = array(
+    t('<strong>Table queue</strong>'),
+    count($view->query->table_queue) . ': (' . implode(', ', array_keys($view->query->table_queue)) . ')',
+  );
+}
+
+/**
+ * This hooks allows to alter the links at the top of the view edit form. Some
+ * modules might want to add links there.
+ *
+ * @param $links
+ *   An array of links which will be displayed at the top of the view edit form.
+ *   Each entry should be on a form suitable for theme('link').
+ * @param view $view
+ *   The full view object which is currently edited.
+ * @param $display_id
+ *   The current display id which is edited. For example that's 'default' or
+ *   'page_1'.
+ */
+function hook_views_ui_display_top_links_alter(&$links, $view, $display_id) {
+  // Put the export link first in the list.
+  if (isset($links['export'])) {
+    $links = array('export' => $links['export']) + $links;
+  }
+}
+
+/**
+ * This hook allows to alter the commands which are used on a views ajax
+ * request.
+ *
+ * @param $commands
+ *   An array of ajax commands
+ * @param $view view
+ *   The view which is requested.
+ */
+function hook_views_ajax_data_alter(&$commands, $view) {
+  // Replace Views' method for scrolling to the top of the element with your
+  // custom scrolling method.
+  foreach ($commands as &$command) {
+    if ($command['method'] == 'viewsScrollTop') {
+      $command['method'] .= 'myScrollTop';
+    }
+  }
+}
+
+/**
+ * Allow modules to respond to the Views cache being invalidated.
+ *
+ * This hook should fire whenever a view is enabled, disabled, created,
+ * updated, or deleted.
+ *
+ * @see views_invalidate_cache()
+ */
+function hook_views_invalidate_cache() {
+  cache_clear_all('views:*', 'cache_mymodule', TRUE);
+}
+
+/**
+ * @}
+ */
+
+/**
+ * @defgroup views_module_handlers Views module handlers
+ * @{
+ * Handlers exposed by various modules to Views.
+ * @}
+ */