core.api.php 78.4 KB
 webchick committed Mar 12, 2014 1 2 3 4 5 6 7 8 9 10 11 get('system.cron_last'); * // Set the cron run time to the current request time. * $state->set('system_cron_last', REQUEST_TIME); * @endcode  webchick committed Mar 12, 2014 191  *  192 193 194 195 196 197 198 199 200 201  * For more on the State API, see https://drupal.org/developing/api/8/state * @} */ /** * @defgroup config_api Configuration API * @{ * Information about the Configuration API. * * The Configuration API is one of several methods in Drupal for storing  202  * information. See the @link info_types Information types topic @endlink for  203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222  * an overview of the different types of information. The sections below have * more information about the configuration API; see * https://drupal.org/developing/api/8/configuration for more details. * * @section sec_storage Configuration storage * In Drupal, there is a concept of the "active" configuration, which is the * configuration that is currently in use for a site. The storage used for the * active configuration is configurable: it could be in the database, in files * in a particular directory, or in other storage backends; the default storage * is in the database. Module developers must use the configuration API to * access the active configuration, rather than being concerned about the * details of where and how it is stored. * * Configuration is divided into individual objects, each of which has a * unique name or key. Some modules will have only one configuration object, * typically called 'mymodule.settings'; some modules will have many. Within * a configuration object, configuration settings have data types (integer, * string, Boolean, etc.) and settings can also exist in a nested hierarchy, * known as a "mapping". *  223 224 225 226  * Configuration can also be overridden on a global, per-language, or * per-module basis. See https://www.drupal.org/node/1928898 for more * information. *  227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250  * @section sec_yaml Configuration YAML files * Whether or not configuration files are being used for the active * configuration storage on a particular site, configuration files are always * used for: * - Defining the default configuration for a module, which is imported to the * active storage when the module is enabled. Note that changes to this * default configuration after a module is already enabled have no effect; * to make a configuration change after a module is enabled, you would need * to uninstall/reinstall or use a hook_update_N() function. * - Exporting and importing configuration. * * The file storage format for configuration information in Drupal is @link * http://en.wikipedia.org/wiki/YAML YAML files. @endlink Configuration is * divided into files, each containing one configuration object. The file name * for a configuration object is equal to the unique name of the configuration, * with a '.yml' extension. The default configuration files for each module are * placed in the config/install directory under the top-level module directory, * so look there in most Core modules for examples. * * Each configuration file has a specific structure, which is expressed as a * YAML-based configuration schema. The configuration schema details the * structure of the configuration, its data types, and which of its values need * to be translatable. Each module needs to define its configuration schema in * files in the config/schema directory under the top-level module directory, so  webchick committed Jun 23, 2014 251 252  * look there in most Core modules for examples. Note that data types label, * text, and data_format are translatable; string is non-translatable text.  253 254 255 256 257 258 259 260 261 262 263 264 265 266 267  * * @section sec_simple Simple configuration * The simple configuration API should be used for information that will always * have exactly one copy or version. For instance, if your module has a * setting that is either on or off, then this is only defined once, and it * would be a Boolean-valued simple configuration setting. * * The first task in using the simple configuration API is to define the * configuration file structure, file name, and schema of your settings (see * @ref sec_yaml above). Once you have done that, you can retrieve the * active configuration object that corresponds to configuration file * mymodule.foo.yml with a call to: * @code *$config = \Drupal::config('mymodule.foo'); * @endcode  webchick committed Mar 12, 2014 268  *  269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324  * This will be an object of class \Drupal\Core\Config\Config, which has methods * for getting and setting configuration information. For instance, if your * YAML file structure looks like this: * @code * enabled: '0' * bar: * baz: 'string1' * boo: 34 * @endcode * you can make calls such as: * @code * // Get a single value. * $enabled =$config->get('enabled'); * // Get an associative array. * $bar =$config->get('bar'); * // Get one element of the array. * $bar_baz =$config->get('bar.baz'); * // Update a value. Nesting works the same as get(). * $config->set('bar.baz', 'string2'); * // Nothing actually happens with set() until you call save(). *$config->save(); * @endcode * * @section sec_entity Configuration entities * In contrast to the simple configuration settings described in the previous * section, if your module allows users to create zero or more items (where * "items" are things like content type definitions, view definitions, and the * like), then you need to define a configuration entity type to store your * configuration. Creating an entity type, loading entites, and querying them * are outlined in the @link entity_api Entity API topic. @endlink Here are a * few additional steps and notes specific to configuration entities: * - For examples, look for classes that implement * \Drupal\Core\Config\Entity\ConfigEntityInterface -- one good example is * the \Drupal\user\Entity\Role entity type. * - In the entity type annotation, you will need to define a 'config_prefix' * string. When Drupal stores a configuration item, it will be given a name * composed of your module name, your chosen config prefix, and the ID of * the individual item, separated by '.'. For example, in the Role entity, * the config prefix is 'role', so one configuration item might be named * user.role.anonymous, with configuration file user.role.anonymous.yml. * - You will need to define the schema for your configuration in your * modulename.schema.yml file, with an entry for 'modulename.config_prefix.*'. * For example, for the Role entity, the file user.schema.yml has an entry * user.role.*; see @ref sec_yaml above for more information. * - Your module may also provide a few configuration items to be installed by * default, by adding configuration files to the module's config/install * directory; see @ref sec_yaml above for more information. * - Some configuration entities have dependencies on other configuration * entities, and module developers need to consider this so that configuration * can be imported, uninstalled, and synchronized in the right order. For * example, a field display configuration entity would need to depend on * field instance configuration, which depends on field and bundle * configuration. Configuration entity classes expose dependencies by * overriding the * \Drupal\Core\Config\Entity\ConfigEntityInterface::calculateDependencies() * method.  webchick committed Jun 23, 2014 325 326 327  * * @see i18n *  webchick committed Mar 12, 2014 328 329 330 331 332 333 334 335  * @} */ /** * @defgroup cache Cache API * @{ * Information about the Drupal Cache API *  webchick committed Mar 20, 2014 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371  * @section basics Basics * * Note: If not specified, all of the methods mentioned here belong to * \Drupal\Core\Cache\CacheBackendInterface. * * The Cache API is used to store data that takes a long time to * compute. Caching can be permanent, temporary, or valid for a certain * timespan, and the cache can contain any type of data. * * To use the Cache API: * - Request a cache object through \Drupal::cache() or by injecting a cache * service. * - Define a Cache ID (cid) value for your data. A cid is a string, which must * contain enough information to uniquely identify the data. For example, if * your data contains translated strings, then your cid value must include the * current interface language. * - Call the get() method to attempt a cache read, to see if the cache already * contains your data. * - If your data is not already in the cache, compute it and add it to the * cache using the set() method. The third argument of set() can be used to * control the lifetime of your cache item. * * Example: * @code * $cid = 'mymodule_example:' . \Drupal::languageManager()->getCurrentLanguage()->id(); * *$data = NULL; * if ($cache = \Drupal::cache()->get($cid)) { * $data =$cache->data; * } * else { * $data = my_module_complicated_calculation(); * \Drupal::cache()->set($cid, $data); * } * @endcode *  jhodgdon committed Mar 28, 2014 372 373 374 375 376 377  * Note the use of$data and $cache->data in the above example. Calls to * \Drupal::cache()->get() return a record that contains the information stored * by \Drupal::cache()->set() in the data property as well as additional meta * information about the cached data. In order to make use of the cached data * you can access it via$cache->data. *  webchick committed Mar 20, 2014 378 379 380 381 382 383 384  * @section bins Cache bins * * Cache storage is separated into "bins", each containing various cache items. * Each bin can be configured separately; see @ref configuration. * * When you request a cache object, you can specify the bin name in your call to * \Drupal::cache(). Alternatively, you can request a bin by getting service  385 386  * "cache.nameofbin" from the container. The default bin is called "default", with * service name "cache.default", it is used to store common and frequently used  387  * caches.  webchick committed Mar 20, 2014 388  *  catch committed Mar 26, 2014 389 390 391 392 393  * Other common cache bins are the following: * - bootstrap: Small caches needed for the bootstrap on every request. * - render: Contains cached HTML strings like cached pages and blocks, can * grow to large size. * - data: Contains data that can vary by path or similar context.  394 395  * - discovery: Contains cached discovery data for things such as plugins, * views_data, or YAML discovered data such as library info.  webchick committed Mar 20, 2014 396 397 398 399 400 401 402 403 404 405 406 407 408  * * A module can define a cache bin by defining a service in its * modulename.services.yml file as follows (substituting the desired name for * "nameofbin"): * @code * cache.nameofbin: * class: Drupal\Core\Cache\CacheBackendInterface * tags: * - { name: cache.bin } * factory_method: get * factory_service: cache_factory * arguments: [nameofbin] * @endcode  alexpott committed Aug 01, 2014 409 410  * See the @link container Services topic @endlink for more on defining * services.  webchick committed Mar 20, 2014 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439  * * @section delete Deletion * * There are two ways to remove an item from the cache: * - Deletion (using delete(), deleteMultiple() or deleteAll()) permanently * removes the item from the cache. * - Invalidation (using invalidate(), invalidateMultiple() or invalidateAll()) * is a "soft" delete that only marks items as "invalid", meaning "not fresh" * or "not fresh enough". Invalid items are not usually returned from the * cache, so in most ways they behave as if they have been deleted. However, * it is possible to retrieve invalid items, if they have not yet been * permanently removed by the garbage collector, by passing TRUE as the second * argument for get($cid,$allow_invalid). * * Use deletion if a cache item is no longer useful; for instance, if the item * contains references to data that has been deleted. Use invalidation if the * cached item may still be useful to some callers until it has been updated * with fresh data. The fact that it was fresh a short while ago may often be * sufficient. * * Invalidation is particularly useful to protect against stampedes. Rather than * having multiple concurrent requests updating the same cache item when it * expires or is deleted, there can be one request updating the cache, while the * other requests can proceed using the stale value. As soon as the cache item * has been updated, all future requests will use the updated value. * * @section tags Cache Tags * * The fourth argument of the set() method can be used to specify cache tags,  alexpott committed Apr 12, 2014 440 441 442 443  * which are used to identify what type of data is included in each cache item. * Each cache item can have multiple cache tags, and each cache tag has a string * key and a value. The value can be: * - TRUE, to indicate that this type of data is present in the cache item.  webchick committed Mar 20, 2014 444  * - An array of values. For example, the "node" tag indicates that particular  alexpott committed Apr 12, 2014 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462  * node's data is present in the cache item, so its value is an array of node * IDs. * Data that has been tagged can be deleted or invalidated as a group: no matter * the Cache ID (cid) of the cache item, no matter in which cache bin a cache * item lives; as long as it is tagged with a certain cache tag, it will be * deleted or invalidated. * * Because of that, cache tags are a solution to the cache invalidation problem: * - For caching to be effective, each cache item must only be invalidated when * absolutely necessary. (i.e. maximizing the cache hit ratio.) * - For caching to be correct, each cache item that depends on a certain thing * must be invalidated whenever that certain thing is modified. * * A typical scenario: a user has modified a node that appears in two views, * three blocks and on twelve pages. Without cache tags, we couldn't possibly * know which cache items to invalidate, so we'd have to invalidate everything: * we had to sacrifice effectiveness to achieve correctness. With cache tags, we * can have both.  webchick committed Mar 20, 2014 463 464 465 466 467 468 469 470 471 472 473  * * Example: * @code * // A cache item with nodes, users, and some custom module data. * $tags = array( * 'my_custom_tag' => TRUE, * 'node' => array(1, 3), * 'user' => array(7), * ); * \Drupal::cache()->set($cid, $data, CacheBackendInterface::CACHE_PERMANENT,$tags); *  alexpott committed Apr 12, 2014 474  * // Delete or invalidate all cache items with certain tags.  alexpott committed Aug 08, 2014 475  * \Drupal\Core\Cache\Cache::deleteTags(array('node' => array(1)));  webchick committed Mar 20, 2014 476 477 478  * \Drupal\Core\Cache\Cache::invalidateTags(array('user' => array(1))); * @endcode *  alexpott committed Apr 12, 2014 479 480 481 482 483 484 485 486 487 488 489 490  * Drupal is a content management system, so naturally you want changes to your * content to be reflected everywhere, immediately. That's why we made sure that * every entity type in Drupal 8 automatically has support for cache tags: when * you save an entity, you can be sure that the cache items that have the * corresponding cache tags will be invalidated. * This also is the case when you define your own entity types: you'll get the * exact same cache tag invalidation as any of the built-in entity types, with * the ability to override any of the default behavior if needed. * See \Drupal\Core\Entity\EntityInterface::getCacheTag(), * \Drupal\Core\Entity\EntityInterface::getListCacheTags(), * \Drupal\Core\Entity\Entity::invalidateTagsOnSave() and * \Drupal\Core\Entity\Entity::invalidateTagsOnDelete().  webchick committed Mar 20, 2014 491  *  alexpott committed Apr 12, 2014 492  * @todo Update cache tag deletion in https://drupal.org/node/918538  webchick committed Mar 20, 2014 493 494 495  * * @section configuration Configuration *  jhodgdon committed Mar 28, 2014 496 497 498  * By default cached data is stored in the database. This can be configured * though so that all cached data, or that of an individual cache bin, uses a * different cache backend, such as APC or Memcache, for storage.  webchick committed Mar 20, 2014 499  *  500 501 502  * In a settings.php file, you can override the service used for a particular * cache bin. For example, if your service implementation of * \Drupal\Core\Cache\CacheBackendInterface was called cache.custom, the  catch committed Mar 26, 2014 503  * following line would make Drupal use it for the 'cache_render' bin:  webchick committed Mar 20, 2014 504  * @code  505  * $settings['cache']['bins']['render'] = 'cache.custom';  webchick committed Mar 20, 2014 506 507 508 509 510  * @endcode * * Additionally, you can register your cache implementation to be used by * default for all cache bins with: * @code  511  *$settings['cache']['default'] = 'cache.custom';  webchick committed Mar 20, 2014 512  * @endcode  webchick committed Mar 12, 2014 513 514 515 516 517 518  * * @see https://drupal.org/node/1884796 * @} */ /**  519  * @defgroup user_api User accounts, permissions, and roles  webchick committed Mar 12, 2014 520 521 522  * @{ * API for user accounts, access checking, roles, and permissions. *  523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552  * @sec sec_overview Overview and terminology * Drupal's permission system is based on the concepts of accounts, roles, * and permissions. * * Users (site visitors) have accounts, which include a user name, an email * address, a password (or some other means of authentication), and possibly * other fields (if defined on the site). Anonymous users have an implicit * account that does not have a real user name or any account information. * * Each user account is assigned one or more roles. The anonymous user account * automatically has the anonymous user role; real user accounts * automatically have the authenticated user role, plus any roles defined on * the site that they have been assigned. * * Each role, including the special anonymous and authenticated user roles, is * granted one or more named permissions, which allow them to perform certain * tasks or view certain content on the site. It is possible to designate a * role to be the "administrator" role; if this is set up, this role is * automatically granted all available permissions whenever a module is * enabled that defines permissions. * * All code in Drupal that allows users to perform tasks or view content must * check that the current user has the correct permission before allowing the * action. In the standard case, access checking consists of answering the * question "Does the current user have permission 'foo'?", and allowing or * denying access based on the answer. Note that access checking should nearly * always be done at the permission level, not by checking for a particular role * or user ID, so that site administrators can set up user accounts and roles * appropriately for their particular sites. *  jhodgdon committed Jul 30, 2014 553  * @section sec_define Defining permissions  554 555 556 557 558  * Modules define permissions by implementing hook_permission(). The return * value defines machine names, human-readable names, and optionally * descriptions for each permission type. The machine names are the canonical * way to refer to permissions for access checking. *  jhodgdon committed Jul 30, 2014 559  * @section sec_access Access permission checking  560 561 562 563 564 565 566 567  * Depending on the situation, there are several methods for ensuring that * access checks are done properly in Drupal: * - Routes: When you register a route, include a 'requirements' section that * either gives the machine name of the permission that is needed to visit the * URL of the route, or tells Drupal to use an access check method or service * to check access. See the @link menu Routing topic @endlink for more * information. * - Entities: Access for various entity operations is designated either with  alexpott committed Aug 07, 2014 568 569 570  * simple permissions or access control handler classes in the entity * annotation. See the @link entity_api Entity API topic @endlink for more * information.  571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586  * - Other code: There is a 'current_user' service, which can be injected into * classes to provide access to the current user account (see the * @link container Services and Dependency Injection topic @endlink for more * information on dependency injection). In code that cannot use dependency * injection, you can access this service and retrieve the current user * account object by calling \Drupal::currentUser(). Once you have a user * object for the current user (implementing \Drupal\user\UserInterface), you * can call inherited method * \Drupal\Core\Session\AccountInterface::hasPermission() to check * permissions, or pass this object into other functions/methods. * - Forms: Each element of a form array can have a Boolean '#access' property, * which determines whether that element is visible and/or usable. This is a * common need in forms, so the current user service (described above) is * injected into the form base class as method * \Drupal\Core\Form\FormBase::currentUser(). *  jhodgdon committed Jul 30, 2014 587  * @section sec_entities User and role objects  588 589 590 591 592 593 594 595 596 597 598 599 600  * User objects in Drupal are entity items, implementing * \Drupal\user\UserInterface. Role objects in Drupal are also entity items, * implementing \Drupal\user\RoleInterface. See the * @link entity_api Entity API topic @endlink for more information about * entities in general (including how to load, create, modify, and query them). * * Roles often need to be manipulated in automated test code, such as to add * permissions to them. Here's an example: * @code * $role = \Drupal\user\Entity\Role::load('authenticated'); *$role->grantPermission('access comments'); * $role->save(); * @endcode  webchick committed Mar 12, 2014 601  *  602 603 604 605 606 607  * Other important interfaces: * - \Drupal\Core\Session\AccountInterface: The part of UserInterface that * deals with access checking. In writing code that checks access, your * method parameters should use this interface, not UserInterface. * - \Drupal\Core\Session\AccountProxyInterface: The interface for the * current_user service (described above).  webchick committed Mar 12, 2014 608 609 610 611 612 613 614 615  * @} */ /** * @defgroup container Services and Dependency Injection Container * @{ * Overview of the Dependency Injection Container and Services. *  alexpott committed Aug 01, 2014 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657  * @section sec_overview Overview of container, injection, and services * The Services and Dependency Injection Container concepts have been adopted by * Drupal from the @link http://symfony.com/ Symfony framework. @endlink A * "service" (such as accessing the database, sending email, or translating user * interface text) is defined (given a name and an interface or at least a * class that defines the methods that may be called), and a default class is * defined to provide the service. These two steps must be done together, and * can be done by Drupal Core or a module. Other modules can then define * alternative classes to provide the same services, overriding the default * classes. Classes and functions that need to use the service should always * instantiate the class via the dependency injection container (also known * simply as the "container"), rather than instantiating a particular service * provider class directly, so that they get the correct class (default or * overridden). * * See https://drupal.org/node/2133171 for more detailed information on * services and the dependency injection container. * * @section sec_discover Discovering existing services * Drupal core defines many core services in the core.services.yml file (in the * top-level core directory). Some Drupal Core modules and contributed modules * also define services in modulename.services.yml files. API reference sites * (such as https://api.drupal.org) generate lists of all existing services from * these files, or you can look through the individual files manually. * * A typical service definition in a *.services.yml file looks like this: * @code * path.alias_manager: * class: Drupal\Core\Path\AliasManager * arguments: ['@path.crud', '@path.alias_whitelist', '@language_manager'] * @endcode * Some services use other services as factories; a typical service definition * is: * @code * cache.entity: * class: Drupal\Core\Cache\CacheBackendInterface * tags: * - { name: cache.bin } * factory_method: get * factory_service: cache_factory * arguments: [entity] * @endcode  webchick committed Mar 12, 2014 658  *  alexpott committed Aug 01, 2014 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791  * The first line of a service definition gives the unique machine name of the * service. This is often prefixed by the module name if provided by a module; * however, by convention some service names are prefixed by a group name * instead, such as cache.* for cache bins and plugin.manager.* for plugin * managers. * * The class line either gives the default class that provides the service, or * if the service uses a factory class, the interface for the service. If the * class depends on other services, the arguments line lists the machine * names of the dependencies (preceded by '@'); objects for each of these * services are instantiated from the container and passed to the class * constructor when the service class is instantiated. Other arguments can also * be passed in; see the section at https://drupal.org/node/2133171 for more * detailed information. * * Services using factories can be defined as shown in the above example, if the * factory is itself a service. The factory can also be a class; details of how * to use service factories can be found in the section at * https://drupal.org/node/2133171. * * @section sec_container Accessing a service through the container * As noted above, if you need to use a service in your code, you should always * instantiate the service class via a call to the container, using the machine * name of the service, so that the default class can be overridden. There are * several ways to make sure this happens: * - For service-providing classes, see other sections of this documentation * describing how to pass services as arguments to the constructor. * - Plugin classes, controllers, and similar classes have create() or * createInstance() methods that are used to create an instance of the class. * These methods come from different interfaces, and have different * arguments, but they all include an argument$container of type * \Symfony\Component\DependencyInjection\ContainerInterface. * If you are defining one of these classes, in the create() or * createInstance() method, call * @code $container->get('myservice.name') @endcode to instantiate a service. * The results of these calls are generally passed to the class constructor * and saved as member variables in the class. * - For functions and class methods that do not have access to either of * the above methods of dependency injection, you can use service location to * access services, via a call to the global \Drupal class. This class has * special methods for accessing commonly-used services, or you can call a * generic method to access any service. Examples: * @code * // Retrieve the entity.manager service object (special method exists). *$manager = \Drupal->entityManager(); * // Retrieve the service object for machine name 'foo.bar'. * $foobar = \Drupal->service('foo.bar'); * @endcode * * As a note, you should always use dependency injection (via service arguments * or create()/createInstance() methods) if possible to instantiate services, * rather than service location (via the \Drupal class), because: * - Dependency injection facilitates writing unit tests, since the container * argument can be mocked and the create() method can be bypassed by using * the class constructor. If you use the \Drupal class, unit tests are much * harder to write and your code has more dependencies. * - Having the service interfaces on the class constructor and member variables * is useful for IDE auto-complete and self-documentation. * * @section sec_define Defining a service * If your module needs to define a new service, here are the steps: * - Choose a unique machine name for your service. Typically, this should * start with your module name. Example: mymodule.myservice. * - Create a PHP interface to define what your service does. * - Create a default class implementing your interface that provides your * service. If your class needs to use existing services (such as database * access), be sure to make these services arguments to your class * constructor, and save them in member variables. Also, if the needed * services are provided by other modules and not Drupal Core, you'll want * these modules to be dependencies of your module. * - Add an entry to a modulename.services.yml file for the service. See * @ref sec_discover above, or existing *.services.yml files in Core, for the * syntax; it will start with your machine name, refer to your default class, * and list the services that need to be passed into your constructor. * * Services can also be defined dynamically, as in the * \Drupal\Core\CoreServiceProvider class, but this is less common for modules. * * @section sec_tags Service tags * Some services have tags, which are defined in the service definition. Tags * are used to define a group of related services, or to specify some aspect of * how the service behaves. Typically, if you tag a service, your service class * must also implement a corresponding interface. Some common examples: * - access_check: Indicates a route access checking service; see the * @link menu Menu and routing system topic @endlink for more information. * - cache.bin: Indicates a cache bin service; see the * @link cache Cache topic @endlink for more information. * - event_subscriber: Indicates an event subscriber service. Event subscribers * can be used for dynamic routing and route altering; see the * @link menu Menu and routing system topic @endlink for more information. * They can also be used for other purposes; see * http://symfony.com/doc/current/cookbook/doctrine/event_listeners_subscribers.html * for more information. * - needs_destruction: Indicates that a destruct() method needs to be called * at the end of a request to finalize operations, if this service was * instantiated. * * Creating a tag for a service does not do anything on its own, but tags * can be discovered or queried in a compiler pass when the container is built, * and a corresponding action can be taken. See * \Drupal\Core\CoreServiceProvider::register() for an example. * * @section sec_injection Overriding the default service class * Modules can override the default classes used for services. Here are the * steps: * - Define a class in the top-level namespace for your module * (Drupal\my_module), whose name is the camel-case version of your module's * machine name followed by "ServiceProvider" (for example, if your module * machine name is my_module, the class must be named * MyModuleServiceProvider). * - The class needs to implement * \Drupal\Core\DependencyInjection\ServiceModifierInterface, which is * typically done by extending * \Drupal\Core\DependencyInjection\ServiceProviderBase. * - The class needs to contain one method: alter(). This method does the * actual work of telling Drupal to use your class instead of the default. * Here's an example: * @code * public function alter(ContainerBuilder$container) { * // Override the language_manager class with a new class. * $definition =$container->getDefinition('language_manager'); * $definition->setClass('Drupal\my_module\MyLanguageManager'); * } * @endcode * Note that$container here is an instance of * \Drupal\Core\DependencyInjection\ContainerBuilder. * * @see https://drupal.org/node/2133171 * @see core.services.yml * @see \Drupal * @see \Symfony\Component\DependencyInjection\ContainerInterface * @see plugin_api * @see menu  webchick committed Mar 12, 2014 792 793 794 795 796 797  * @} */ /** * @defgroup typed_data Typed Data API * @{  webchick committed Jun 16, 2014 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851  * API for describing data based on a set of available data types. * * The Typed Data API was created to provide developers with a consistent * interface for interacting with data, as well as an API for metadata * (information about the data, such as the data type, whether it is * translatable, and who can access it). The Typed Data API is used in several * Drupal sub-systems, such as the Entity Field API and Configuration API. * * See https://drupal.org/node/1794140 for more information about the Typed * Data API. * * @section interfaces Interfaces and classes in the Typed Data API * There are several basic interfaces in the Typed Data API, representing * different types of data: * - \Drupal\Core\TypedData\PrimitiveInterface: Used for primitive data, such * as strings, numeric types, etc. Drupal provides primitive types for * integers, strings, etc. based on this interface, and you should * not ever need to create new primitive types. * - \Drupal\Core\TypedData\TypedDataInterface: Used for single pieces of data, * with some information about its context. Abstract base class * \Drupal\Core\TypedData\TypedData is a useful starting point, and contains * documentation on how to extend it. * - \Drupal\Core\TypedData\ComplexDataInterface: Used for complex data, which * contains named and typed properties; extends TypedDataInterface. Examples * of complex data include content entities and field items. See the * @link entity_api Entity API topic @endlink for more information about * entities; for most complex data, developers should use entities. * - \Drupal\Core\TypedData\ListInterface: Used for a sequential list of other * typed data. Class \Drupal\Core\TypedData\Plugin\DataType\ItemList is a * generic implementation of this interface, and it is used by default for * data declared as a list of some other data type. You can also define a * custom list class, in which case ItemList is a useful base class. * * @section defining Defining data types * To define a new data type: * - Create a class that implements one of the Typed Data interfaces. * Typically, you will want to extend one of the classes listed in the * section above as a starting point. * - Make your class into a DataType plugin. To do that, put it in namespace * \Drupal\yourmodule\Plugin\DataType (where "yourmodule" is your module's * short name), and add annotation of type * \Drupal\Core\TypedData\Annotation\DataType to the documentation header. * See the @link plugin_api Plugin API topic @endlink and the * @link annotation Annotations topic @endlink for more information. * * @section using Using data types * The data types of the Typed Data API can be used in several ways, once they * have been defined: * - In the Field API, data types can be used as the class in the property * definition of the field. See the @link field Field API topic @endlink for * more information. * - In configuration schema files, you can use the unique ID ('id' annotation) * from any DataType plugin class as the 'type' value for an entry. See the * @link config_api Confuration API topic @endlink for more information.  webchick committed Mar 12, 2014 852 853 854 855 856 857 858 859  * @} */ /** * @defgroup testing Automated tests * @{ * Overview of PHPUnit tests and Simpletest tests. *  webchick committed Jun 16, 2014 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949  * The Drupal project has embraced a philosophy of using automated tests, * consisting of both unit tests (which test the functionality of classes at a * low level) and functional tests (which test the functionality of Drupal * systems at a higher level, usually involving web output). The goal is to * have test coverage for all or most of the components and features, and to * run the automated tests before any code is changed or added, to make sure * it doesn't break any existing functionality (regression testing). * * In order to implement this philosophy, developers need to do the following: * - When making a patch to fix a bug, make sure that the bug fix patch includes * a test that fails without the code change and passes with the code change. * This helps reviewers understand what the bug is, demonstrates that the code * actually fixes the bug, and ensures the bug will not reappear due to later * code changes. * - When making a patch to implement a new feature, include new unit and/or * functional tests in the patch. This serves to both demonstrate that the * code actually works, and ensure that later changes do not break the new * functionality. * * @section write_unit Writing PHPUnit tests for classes * PHPUnit tests for classes are written using the industry-standard PHPUnit * framework. Use a PHPUnit test to test functionality of a class if the Drupal * environment (database, settings, etc.) and web browser are not needed for the * test, or if the Drupal environment can be replaced by a "mock" object. To * write a PHPUnit test: * - Define a class that extends \Drupal\Tests\UnitTestCase. * - The class name needs to end in the word Test. * - The namespace must be a subspace/subdirectory of \Drupal\yourmodule\Tests, * where yourmodule is your module's machine name. * - The test class file must be named and placed under the yourmodule/tests/src * directory, according to the PSR-4 standard. * - Your test class needs a getInfo() method, which gives information about * the test. * - Methods in your test class whose names start with 'test' are the actual * test cases. Each one should test a logical subset of the functionality. * For more details, see: * - https://drupal.org/phpunit for full documentation on how to write PHPUnit * tests for Drupal. * - http://phpunit.de for general information on the PHPUnit framework. * - @link oo_conventions Object-oriented programming topic @endlink for more * on PSR-4, namespaces, and where to place classes. * * @section write_functional Writing functional tests * Functional tests are written using a Drupal-specific framework that is, for * historical reasons, known as "Simpletest". Use a Simpletest test to test the * functionality of sub-system of Drupal, if the functionality depends on the * Drupal database and settings, or to test the web output of Drupal. To * write a Simpletest test: * - For functional tests of the web output of Drupal, define a class that * extends \Drupal\simpletest\WebTestBase, which contains an internal web * browser and defines many helpful test assertion methods that you can use * in your tests. You can specify modules to be enabled by defining a * $modules member variable -- keep in mind that by default, WebTestBase uses * a "testing" install profile, with a minimal set of modules enabled. * - For functional tests that do not test web output, define a class that * extends \Drupal\simpletest\KernelTestBase. This class is much faster * than WebTestBase, because instead of making a full install of Drupal, it * uses an in-memory pseudo-installation (similar to what the installer and * update scripts use). To use this test class, you will need to create the * database tables you need and install needed modules manually. * - The namespace must be a subspace/subdirectory of \Drupal\yourmodule\Tests, * where yourmodule is your module's machine name. * - The test class file must be named and placed under the yourmodule/src/Tests * directory, according to the PSR-4 standard. * - Your test class needs a getInfo() method, which gives information about * the test. * - You may also override the default setUp() method, which can set be used to * set up content types and similar procedures. * - In some cases, you may need to write a test module to support your test; * put such modules under the yourmodule/tests/modules directory. * - Methods in your test class whose names start with 'test', and which have * no arguments, are the actual test cases. Each one should test a logical * subset of the functionality, and each one runs in a new, isolated test * environment, so it can only rely on the setUp() method, not what has * been set up by other test methods. * For more details, see: * - https://drupal.org/simpletest for full documentation on how to write * functional tests for Drupal. * - @link oo_conventions Object-oriented programming topic @endlink for more * on PSR-4, namespaces, and where to place classes. * * @section running Running tests * You can run both Simpletest and PHPUnit tests by enabling the core Testing * module (core/modules/simpletest). Once that module is enabled, tests can be * run usin the core/scripts/run-tests.sh script, using * @link https://drupal.org/project/drush Drush @endlink, or from the Testing * module user interface. * * PHPUnit tests can also be run from the command line, using the PHPUnit * framework. See https://drupal.org/node/2116263 for more information.  webchick committed Mar 12, 2014 950 951 952 953  * @} */ /**  954  * @defgroup info_types Information types  webchick committed Mar 12, 2014 955  * @{  956  * Types of information in Drupal.  webchick committed Mar 12, 2014 957  *  958 959 960 961 962 963 964 965  * Drupal has several distinct types of information, each with its own methods * for storage and retrieval: * - Content: Information meant to be displayed on your site: articles, basic * pages, images, files, custom blocks, etc. Content is stored and accessed * using @link entity_api Entities @endlink. * - Session: Information about individual users' interactions with the site, * such as whether they are logged in. This is really "state" information, but * it is not stored the same way so it's a separate type here. Session  966 967 968 969  * information is managed via the session_manager service in Drupal, which * implements \Drupal\Core\Session\SessionManagerInterface. See the * @link container Services topic @endlink for more information about * services.  970 971 972 973 974 975 976 977 978 979  * - State: Information of a temporary nature, generally machine-generated and * not human-edited, about the current state of your site. Examples: the time * when Cron was last run, whether node access permissions need rebuilding, * etc. See @link state_api the State API topic @endlink for more information. * - Configuration: Information about your site that is generally (or at least * can be) human-edited, but is not Content, and is meant to be relatively * permanent. Examples: the name of your site, the content types and views * you have defined, etc. See * @link config_api the Configuration API topic @endlink for more information. *  980 981  * @see cache * @see i18n  webchick committed Mar 12, 2014 982 983 984 985  * @} */ /**  webchick committed Apr 30, 2014 986  * @defgroup extending Extending and altering Drupal  webchick committed Mar 12, 2014 987  * @{  webchick committed Apr 30, 2014 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012  * Overview of add-ons and alteration methods for Drupal. * * Drupal's core behavior can be extended and altered via these three basic * types of add-ons: * - Themes: Themes alter the appearance of Drupal sites. They can include * template files, which alter the HTML markup and other raw output of the * site; CSS files, which alter the styling applied to the HTML; and * JavaScript, Flash, images, and other files. For more information, see the * @link theme_render Theme system and render API topic @endlink and * https://drupal.org/theme-guide/8 * - Modules: Modules add to or alter the behavior and functionality of Drupal, * by using one or more of the methods listed below. For more information * about creating modules, see https://drupal.org/developing/modules/8 * - Installation profiles: Installation profiles can be used to * create distributions, which are complete specific-purpose packages of * Drupal including additional modules, themes, and data. For more * information, see https://drupal.org/documentation/build/distributions. * * Here is a list of the ways that modules can alter or extend Drupal's core * behavior, or the behavior of other modules: * - Hooks: Specially-named functions that a module defines, which are * discovered and called at specific times, usually to alter behavior or data. * See the @link hooks Hooks topic @endlink for more information. * - Plugins: Classes that a module defines, which are discovered and * instantiated at specific times to add functionality. See the  webchick committed Jun 20, 2014 1013  * @link plugin_api Plugin API topic @endlink for more information.  webchick committed Apr 30, 2014 1014 1015 1016 1017  * - Entities: Special plugins that define entity types for storing new types * of content or configuration in Drupal. See the * @link entity_api Entity API topic @endlink for more information. * - Services: Classes that perform basic operations within Drupal, such as  webchick committed Jun 09, 2014 1018  * accessing the database and sending email. See the  webchick committed Apr 30, 2014 1019 1020 1021 1022 1023 1024 1025 1026 1027  * @link container Dependency Injection Container and Services topic @endlink * for more information. * - Routing: Providing or altering "routes", which are URLs that Drupal * responds to, or altering routing behavior with event listener classes. * See the @link menu Routing and menu topic @endlink for more information. * @} */ /**  webchick committed Jun 20, 2014 1028  * @defgroup plugin_api Plugin API  webchick committed Apr 30, 2014 1029  * @{  webchick committed Jun 20, 2014 1030  * Using the Plugin API  webchick committed Mar 12, 2014 1031  *  webchick committed Jun 20, 2014 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099  * @section sec_overview Overview and terminology * The basic idea of plugins is to allow a particular module or subsystem of * Drupal to provide functionality in an extensible, object-oriented way. The * controlling module or subsystem defines the basic framework (interface) for * the functionality, and other modules can create plugins (implementing the * interface) with particular behaviors. The controlling module instantiates * existing plugins as needed, and calls methods to invoke their functionality. * Examples of functionality in Drupal Core that use plugins include: the block * system (block types are plugins), the entity/field system (entity types, * field types, field formatters, and field widgets are plugins), the image * manipulation system (image effects and image toolkits are plugins), and the * search system (search page types are plugins). * * Plugins are grouped into plugin types, each generally defined by an * interface. Each plugin type is managed by a plugin manager service, which * uses a plugin discovery method to discover provided plugins of that type and * instantiate them using a plugin factory. * * Some plugin types make use of the following concepts or components: * - Plugin derivatives: Allows a single plugin class to present itself as * multiple plugins. Example: the Menu module provides a block for each * defined menu via a block plugin derivative. * - Plugin mapping: Allows a plugin class to map a configuration string to an * instance, and have the plugin automatically instantiated without writing * additional code. * - Plugin bags: Provide a way to lazily instantiate a set of plugin * instances from a single plugin definition. * * There are several things a module developer may need to do with plugins: * - Define a completely new plugin type: see @ref sec_define below. * - Create a plugin of an existing plugin type: see @ref sec_create below. * - Perform tasks that involve plugins: see @ref sec_use below. * * See https://drupal.org/developing/api/8/plugins for more detailed * documentation on the plugin system. There are also topics for a few * of the many existing types of plugins: * - @link block_api Block API @endlink * - @link entity_api Entity API @endlink * - @link field Various types of field-related plugins @endlink * - @link views_plugins Views plugins @endlink (has links to topics covering * various specific types of Views plugins). * - @link search Search page plugins @endlink * * @section sec_define Defining a new plugin type * To define a new plugin type: * - Define an interface for the plugin. This describes the common set of * behavior, and the methods you will call on each plugin class that is * instantiated. Usually this interface will extend one or more of the * following interfaces: * - \Drupal\Component\Plugin\PluginInspectionInterface * - \Drupal\Component\Plugin\ConfigurablePluginInterface * - \Drupal\Component\Plugin\ContextAwarePluginInterface * - \Drupal\Core\Plugin\PluginFormInterface * - \Drupal\Core\Executable\ExecutableInterface * - (optional) Create a base class that provides a partial implementation of * the interface, for the convenience of developers wishing to create plugins * of your type. The base class usually extends * \Drupal\Core\Plugin\PluginBase, or one of the base classes that extends * this class. * - Choose a method for plugin discovery, and define classes as necessary. * See @ref sub_discovery below. * - Create a plugin manager/factory class and service, which will discover and * instantiate plugins. See @ref sub_manager below. * - Use the plugin manager to instantiate plugins. Call methods on your plugin * interface to perform the tasks of your plugin type. * - (optional) If appropriate, define a plugin bag. See @ref sub_bag below * for more information.  webchick committed Apr 30, 2014 1100  *  webchick committed Jun 20, 2014 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198  * @subsection sub_discovery Plugin discovery * Plugin discovery is the process your plugin manager uses to discover the * individual plugins of your type that have been defined by your module and * other modules. Plugin discovery methods are classes that implement * \Drupal\Component\Plugin\Discovery\DiscoveryInterface. Most plugin types use * one of the following discovery mechanisms: * - Annotation: Plugin classes are annotated and placed in a defined namespace * subdirectory. Most Drupal Core plugins use this method of discovery. * - Hook: Plugin modules need to implement a hook to tell the manager about * their plugins. * - YAML: Plugins are listd in YAML files. Drupal Core uses this method for * discovering local tasks and local actions. This is mainly useful if all * plugins use the same class, so it is kind of like a global derivative. * - Static: Plugin classes are registered within the plugin manager class * itself. Static discovery is only useful if modules cannot define new * plugins of this type (if the list of available plugins is static). * * It is also possible to define your own custom discovery mechanism or mix * methods together. And there are many more details, such as annotation * decorators, that apply to some of the discovery methods. See * https://drupal.org/developing/api/8/plugins for more details. * * The remainder of this documentation will assume Annotation-based discovery, * since this is the most common method. * * @subsection sub_manager Defining a plugin manager class and service * To define an annotation-based plugin manager: * - Choose a namespace subdirectory for your plugin. For example, search page * plugins go in directory Plugin/Search under the module namespace. * - Define an annotation class for your plugin type. This class should extend * \Drupal\Component\Annotation\Plugin, and for most plugin types, it should * contain member variables corresponding to the annotations plugins will * need to provide. All plugins have at least$id: a unique string * identifier. * - Define an alter hook for altering the discovered plugin definitions. You * should document the hook in a *.api.php file. * - Define a plugin manager class. This class should implement * \Drupal\Component\Plugin\PluginManagerInterface; most plugin managers do * this by extending \Drupal\Core\Plugin\DefaultPluginManager. If you do * extend the default plugin manager, the only method you will probably need * to define is the class constructor, which will need to call the parent * constructor to provide information about the annotation class and plugin * namespace for discovery, set up the alter hook, and possibly set up * caching. See classes that extend DefaultPluginManager for examples. * - Define a service for your plugin manager. See the * @link container Services topic for more information. @endlink Your service * definition should look something like this, referencing your manager * class and the parent (default) plugin manager service to inherit * constructor arguments: * @code * plugin.manager.mymodule: * class: Drupal\mymodule\MyPluginManager * parent: default_plugin_manager * @endcode * - If your plugin is configurable, you will also need to define the * configuration schema and possibly a configuration entity type. See the * @link config_api Configuration API topic @endlink for more information. * * @subsection sub_bag Defining a plugin bag * Some configurable plugin types allow administrators to create zero or more * instances of each plugin, each with its own configuration. For example, * a single block plugin can be configured several times, to display in * different regions of a theme, with different visibility settings, a * different title, or other plugin-specific settings. To make this possible, * a plugin type can make use of what's known as a plugin bag. * * A plugin bag is a class that extends \Drupal\Component\Plugin\PluginBag or * one of its subclasses; there are several examples in Drupal Core. If your * plugin type uses a plugin bag, it will usually also have a configuration * entity, and the entity class should implement * \Drupal\Core\Entity\EntityWithPluginBagsInterface. Again, * there are several examples in Drupal Core; see also the * @link config_api Configuration API topic @endlink for more information about * configuration entities. * * @section sec_create Creating a plugin of an existing type * Assuming the plugin type uses annotation-based discovery, in order to create * a plugin of an existing type, you will be creating a class. This class must: * - Implement the plugin interface, so that it has the required methods * defined. Usually, you'll want to extend the plugin base class, if one has * been provided. * - Have the right annotation in its documentation header. See the * @link annotation Annotation topic @endlink for more information about * annotation. * - Be in the right plugin namespace, in order to be discovered. * Often, the easiest way to make sure this happens is to find an existing * example of a working plugin class of the desired type, and copy it into your * module as a starting point. * * You can also create a plugin derivative, which allows your plugin class * to present itself to the user interface as multiple plugins. To do this, * in addition to the plugin class, you'll need to create a separate plugin * derivative class implementing * \Drupal\Component\Plugin\Derivative\DerivativeInterface. The classes * \Drupal\system\Plugin\Block\SystemMenuBlock (plugin class) and * \Drupal\system\Plugin\Derivative\SystemMenuBlock (derivative class) are a * good example to look at. *  jhodgdon committed Jul 30, 2014 1199  * @section sec_use Performing tasks involving plugins  webchick committed Jun 20, 2014 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210  * Here are the steps to follow to perform a task that involves plugins: * - Locate the machine name of the plugin manager service, and instantiate the * service. See the @link container Services topic @endlink for more * information on how to do this. * - On the plugin manager class, use methods like getDefinition(), * getDefinitions(), or other methods specific to particular plugin managers * to retrieve information about either specific plugins or the entire list of * defined plugins. * - Call the createInstance() method on the plugin manager to instantiate * individual plugin objects. * - Call methods on the plugin objects to perform the desired tasks.  webchick committed Apr 30, 2014 1211 1212  * * @see annotation  webchick committed Mar 12, 2014 1213 1214 1215 1216 1217 1218 1219 1220  * @} */ /** * @defgroup oo_conventions Objected-oriented programming conventions * @{ * PSR-4, namespaces, class naming, and other conventions. *  1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247  * A lot of the PHP code in Drupal is object oriented (OO), making use of * @link http://php.net/manual/language.oop5.php PHP classes, interfaces, and traits @endlink * (which are loosely referred to as "classes" in the rest of this topic). The * following conventions and standards apply to this version of Drupal: * - Each class must be in its own file. * - Classes must be namespaced. If a module defines a class, the namespace * must start with \Drupal\module_name. If it is defined by Drupal Core for * use across many modules, the namespace should be \Drupal\Core or * \Drupal\Component, with the exception of the global class \Drupal. See * https://www.drupal.org/node/1353118 for more about namespaces. * - In order for the PSR-4-based class auto-loader to find the class, it must * be located in a directory corresponding to the namespace. For * module-defined classes, if the namespace is \Drupal\module_name\foo\bar, * then the class goes under the main module directory in directory * src/foo/bar. For Drupal-wide classes, if the namespace is * \Drupal\Core\foo\bar, then it goes in directory * core/lib/Drupal/Core/foo/bar. See https://www.drupal.org/node/2156625 for * more information about PSR-4. * - Some classes have annotations added to their documentation headers. See * the @link annotation Annotation topic @endlink for more information. * - Standard plugin discovery requires particular namespaces and annotation * for most plugin classes. See the * @link plugin_api Plugin API topic @endlink for more information. * - There are project-wide coding standards for OO code, including naming: * https://drupal.org/node/608152 * - Documentation standards for classes are covered on: * https://www.drupal.org/coding-standards/docs#classes  webchick committed Mar 12, 2014 1248 1249 1250 1251 1252 1253  * @} */ /** * @defgroup best_practices Best practices for developers * @{  1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272  * Overview of standards and best practices for developers * * Ideally, all code that is included in Drupal Core and contributed modules, * themes, and distributions will be secure, internationalized, maintainable, * and efficient. In order to facilitate this, the Drupal community has * developed a set of guidelines and standards for developers to follow. Most of * these standards can be found under * @link https://drupal.org/developing/best-practices Best practices on Drupal.org @endlink * * Standards and best practices that developers should be aware of include: * - Security: https://drupal.org/writing-secure-code and the * @link sanitization Sanitization functions topic @endlink * - Coding standards: https://drupal.org/coding-standards * and https://drupal.org/coding-standards/docs * - Accessibility: https://drupal.org/node/1637990 (modules) and * https://drupal.org/node/464472 (themes) * - Usability: https://drupal.org/ui-standards * - Internationalization: @link i18n Internationalization topic @endlink * - Automated testing: @link testing Automated tests topic @endlink  webchick committed Mar 12, 2014 1273 1274  * @} */  jhodgdon committed Mar 28, 2014 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295  /** * @defgroup utility Utility classes and functions * @{ * Overview of utility classes and functions for developers. * * Drupal provides developers with a variety of utility functions that make it * easier and more efficient to perform tasks that are either really common, * tedious, or difficult. Utility functions help to reduce code duplication and * should be used in place of one-off code whenever possible. * * @see common.inc * @see file * @see format * @see mail.inc * @see php_wrappers * @see sanitization * @see transliteration * @see validation * @} */  1296   jhodgdon committed Jul 29, 2014 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 /** * @defgroup hooks Hooks * @{ * Define functions that alter the behavior of Drupal core. * * One way for modules to alter the core behavior of Drupal (or another module) * is to use hooks. Hooks are specially-named functions that a module defines * (this is known as "implementing the hook"), which are discovered and called * at specific times to alter or add to the base behavior or data (this is * known as "invoking the hook"). Each hook has a name (example: * hook_batch_alter()), a defined set of parameters, and a defined return value. * Your modules can implement hooks that are defined by Drupal core or other * modules that they interact with. Your modules can also define their own * hooks, in order to let other modules interact with them. * * To implement a hook: * - Locate the documentation for the hook. Hooks are documented in *.api.php * files, by defining functions whose name starts with "hook_" (these * files and their functions are never loaded by Drupal -- they exist solely * for documentation). The function should have a documentation header, as * well as a sample function body. For example, in the core file * system.api.php, you can find hooks such as hook_batch_alter(). Also, if * you are viewing this documentation on an API reference site, the Core * hooks will be listed in this topic. * - Copy the function to your module's .module file. * - Change the name of the function, substituting your module's short name * (name of the module's directory, and .info.yml file without the extension) * for the "hook" part of the sample function name. For instance, to implemnt * hook_batch_alter(), you would rename it to my_module_batch_alter(). * - Edit the documentation for the function (normally, your implementation * should just have one line saying "Implements hook_batch_alter()."). * - Edit the body of the function, substituting in what you need your module * to do. * * To define a hook: * - Choose a unique name for your hook. It should start with "hook_", followed * by your module's short name. * - Provide documentation in a *.api.php file in your module's main * directory. See the "implementing" section above for details of what this * should contain (parameters, return value, and sample function body). * - Invoke the hook in your module's code. * * To invoke a hook, use methods on * \Drupal\Core\Extension\ModuleHandlerInterface such as alter(), invoke(), * and invokeAll(). You can obtain a module handler by calling * \Drupal::moduleHandler(), or getting the 'module_handler' service on an * injected container. * * @see extending * @see themeable * @see callbacks * @see \Drupal\Core\Extension\ModuleHandlerInterface * @see \Drupal::moduleHandler() * * @} */ /** * @defgroup callbacks Callbacks * @{ * Callback function signatures. * * Drupal's API sometimes uses callback functions to allow you to define how * some type of processing happens. A callback is a function with a defined * signature, which you define in a module. Then you pass the function name as * a parameter to a Drupal API function or return it as part of a hook * implementation return value, and your function is called at an appropriate * time. For instance, when setting up batch processing you might need to * provide a callback function for each processing step and/or a callback for * when processing is finished; you would do that by defining these functions * and passing their names into the batch setup function. * * Callback function signatures, like hook definitions, are described by * creating and documenting dummy functions in a *.api.php file; normally, the * dummy callback function's name should start with "callback_", and you should * document the parameters and return value and provide a sample function body. * Then your API documentation can refer to this callback function in its * documentation. A user of your API can usually name their callback function * anything they want, although a standard name would be to replace "callback_" * with the module name. * * @see hooks * @see themeable * * @} */ /** * @defgroup form_api Form generation * @{ * Describes how to generate and manipulate forms and process form submissions. * * Drupal provides a Form API in order to achieve consistency in its form * processing and presentation, while simplifying code and reducing the amount * of HTML that must be explicitly generated by a module. * * @section generating_forms Creating forms * Forms are defined as classes that implement the * \Drupal\Core\Form\FormInterface and are built using the * \Drupal\Core\Form\FormBuilder class. Drupal provides a couple of utility * classes that can be extended as a starting point for most basic forms, the * most commonly used of which is \Drupal\Core\Form\FormBase. FormBuilder * handles the low level processing of forms such as rendering the necessary * HTML, initial processing of incoming $_POST data, and delegating to your * implementation of FormInterface for validation and processing of submitted * data. * * Here is an example of a Form class: * @code * namespace Drupal\mymodule\Form; * * use Drupal\Core\Form\FormBase;  alexpott committed Aug 01, 2014 1409  * use Drupal\Core\Form\FormStateInterface;  jhodgdon committed Jul 29, 2014 1410 1411 1412 1413 1414 1415 1416  * * class ExampleForm extends FormBase { * public function getFormId() { * // Unique ID of the form. * return 'example_form'; * } *  1417  * public function buildForm(array$form, FormStateInterface $form_state) {  jhodgdon committed Jul 29, 2014 1418 1419 1420 1421 1422 1423 1424 1425  * // Create a$form API array. * $form['phone_number'] = array( * '#type' => 'tel', * '#title' =>$this->t('Your phone number') * ); * return $form; * } *  1426  * public function validateForm(array &$form, FormStateInterface $form_state) {  jhodgdon committed Jul 29, 2014 1427 1428 1429  * // Validate submitted form data. * } *  1430  * public function submitForm(array &$form, FormStateInterface $form_state) {  jhodgdon committed Jul 29, 2014 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454  * // Handle submitted form data. * } * } * @endcode * * @section retrieving_forms Retrieving and displaying forms * \Drupal::formBuilder()->getForm() should be used to handle retrieving, * processing, and displaying a rendered HTML form. Given the ExampleForm * defined above, * \Drupal::formBuilder()->getForm('Drupal\mymodule\Form\ExampleForm') would * return the rendered HTML of the form defined by ExampleForm::buildForm(), or * call the validateForm() and submitForm(), methods depending on the current * processing state. * * The argument to \Drupal::formBuilder()->getForm() is the name of a class that * implements FormBuilderInterface. Any additional arguments passed to the * getForm() method will be passed along as additional arguments to the * ExampleForm::buildForm() method. * * For example: * @code *$extra = '612-123-4567'; * $form = \Drupal::formBuilder()->getForm('Drupal\mymodule\Form\ExampleForm',$extra); * ...  1455  * public function buildForm(array $form, FormStateInterface$form_state, $extra = NULL)  jhodgdon committed Jul 29, 2014 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490  *$form['phone_number'] = array( * '#type' => 'tel', * '#title' => $this->t('Your phone number'), * '#value' =>$extra, * ); * return $form; * } * @endcode * * Alternatively, forms can be built directly via the routing system which will * take care of calling \Drupal::formBuilder()->getForm(). The following example * demonstrates the use of a routing.yml file to display a form at the the * given route. * * @code * example.form: * path: '/example-form' * defaults: * _title: 'Example form' * _form: '\Drupal\mymodule\Form\ExampleForm' * @endcode * * The$form argument to form-related functions is a structured array containing * the elements and properties of the form. For information on the array * components and format, and more detailed explanations of the Form API * workflow, see the * @link forms_api_reference.html Form API reference @endlink * and the * @link https://drupal.org/node/2117411 Form API documentation section. @endlink * In addition, there is a set of Form API tutorials in * @link form_example_tutorial.inc the Form Example Tutorial @endlink which * provide basics all the way up through multistep forms. * * In the form builder, validation, submission, and other form methods, * $form_state is the primary influence on the processing of the form and is  alexpott committed Aug 01, 2014 1491 1492 1493  * passed to most methods, so they can use it to communicate with the form * system and each other.$form_state is an object that implements * \Drupal\Core\Form\FormStateInterface.  jhodgdon committed Aug 13, 2014 1494  * @}  jhodgdon committed Jul 29, 2014 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545  */ /** * @defgroup queue Queue operations * @{ * Queue items to allow later processing. * * The queue system allows placing items in a queue and processing them later. * The system tries to ensure that only one consumer can process an item. * * Before a queue can be used it needs to be created by * Drupal\Core\Queue\QueueInterface::createQueue(). * * Items can be added to the queue by passing an arbitrary data object to * Drupal\Core\Queue\QueueInterface::createItem(). * * To process an item, call Drupal\Core\Queue\QueueInterface::claimItem() and * specify how long you want to have a lease for working on that item. * When finished processing, the item needs to be deleted by calling * Drupal\Core\Queue\QueueInterface::deleteItem(). If the consumer dies, the * item will be made available again by the Drupal\Core\Queue\QueueInterface * implementation once the lease expires. Another consumer will then be able to * receive it when calling Drupal\Core\Queue\QueueInterface::claimItem(). * Due to this, the processing code should be aware that an item might be handed * over for processing more than once. * * The $item object used by the Drupal\Core\Queue\QueueInterface can contain * arbitrary metadata depending on the implementation. Systems using the * interface should only rely on the data property which will contain the * information passed to Drupal\Core\Queue\QueueInterface::createItem(). * The full queue item returned by Drupal\Core\Queue\QueueInterface::claimItem() * needs to be passed to Drupal\Core\Queue\QueueInterface::deleteItem() once * processing is completed. * * There are two kinds of queue backends available: reliable, which preserves * the order of messages and guarantees that every item will be executed at * least once. The non-reliable kind only does a best effort to preserve order * in messages and to execute them at least once but there is a small chance * that some items get lost. For example, some distributed back-ends like * Amazon SQS will be managing jobs for a large set of producers and consumers * where a strict FIFO ordering will likely not be preserved. Another example * would be an in-memory queue backend which might lose items if it crashes. * However, such a backend would be able to deal with significantly more writes * than a reliable queue and for many tasks this is more important. See * aggregator_cron() for an example of how to effectively utilize a * non-reliable queue. Another example is doing Twitter statistics -- the small * possibility of losing a few items is insignificant next to power of the * queue being able to keep up with writes. As described in the processing * section, regardless of the queue being reliable or not, the processing code * should be aware that an item might be handed over for processing more than * once (because the processing code might time out before it finishes).  jhodgdon committed Aug 13, 2014 1546  * @}  1547  */  alexpott committed Aug 10, 2014 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598  /** * @defgroup annotation Annotations * @{ * Annotations for class discovery and metadata description. * * The Drupal plugin system has a set of reusable components that developers * can use, override, and extend in their modules. Most of the plugins use * annotations, which let classes register themselves as plugins and describe * their metadata. (Annotations can also be used for other purposes, though * at the moment, Drupal only uses them for the plugin system.) * * To annotate a class as a plugin, add code similar to the following to the * end of the documentation block immediately preceding the class declaration: * @code * * @ContentEntityType( * * id = "comment", * * label = @Translation("Comment"), * * ... * * base_table = "comment" * * ) * @endcode * * Note that you must use double quotes; single quotes will not work in * annotations. * * Some annotation types, which extend the "@ PluginID" annotation class, have * only a single 'id' key in their annotation. For these, it is possible to use * a shorthand annotation. For example: * @code * * @ViewsArea("entity") * @endcode * in place of * @code * * @ViewsArea( * * id = "entity" * *) * @endcode * * The available annotation classes are listed in this topic, and can be * identified when you are looking at the Drupal source code by having * "@ Annotation" in their documentation blocks (without the space after @). To * find examples of annotation for a particular annotation class, such as * EntityType, look for class files that have an @ annotation section using the * annotation class. * * @see plugin_translatable * @see plugin_context * * @} */  jhodgdon committed Aug 13, 2014 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620  /** * @addtogroup hooks * @{ */ /** * Alter display variant plugin definitions. * * @param array$definitions * The array of display variant definitions, keyed by plugin ID. * * @see \Drupal\Core\Display\VariantManager * @see \Drupal\Core\Display\Annotation\DisplayVariant */ function hook_display_variant_plugin_alter(array &$definitions) {$definitions['full_page']['admin_label'] = t('Block layout'); } /** * @} End of "addtogroup hooks". */