Issue #1970360 by Crell, linclark, dawehner, YesCT, matt2000: Entities should define URI templates and standard links.

core/lib/Drupal/Core/Entity/Annotation/EntityType.php

@@ -252,6 +252,41 @@ class EntityType extends Plugin {
    */
   public $menu_path_wildcard;
 
+  /**
+   * Link templates using the URI template syntax.
+   *
+   * Links are an array of standard link relations to the URI template that
+   * should be used for them. Where possible, link relationships should use
+   * established IANA relationships rather than custom relationships.
+   *
+   * Every entity type should, at minimum, define "canonical", which is the
+   * pattern for URIs to that entity. Even if the entity will have no HTML page
+   * exposed to users it should still have a canonical URI in order to be
+   * compatible with web services. Entities that will be user-editable via an
+   * HTML page must also define an "edit-form" relationship.
+   *
+   * By default, the following placeholders are supported:
+   * - entityType: The machine name of the entity type.
+   * - bundle: The bundle machine name of the entity.
+   * - id: The unique ID of the entity.
+   * - uuid: The UUID of the entity.
+   * - [entityType]: The entity type itself will also be a valid token for the
+   *   ID of the entity. For instance, a placeholder of {node} used on the Node
+   *   class would have the same value as {id}. This is generally preferred
+   *   over "id" for better self-documentation.
+   *
+   * Specific entity types may also expand upon this list by overriding the
+   * uriPlaceholderReplacements() method.
+   *
+   * @link http://www.iana.org/assignments/link-relations/link-relations.xml @endlink
+   * @link http://tools.ietf.org/html/rfc6570 @endlink
+   *
+   * @var array
+   */
+  public $links = array(
+    'canonical' => '/entity/{entityType}/{id}',
+  );
+
   /**
    * Specifies whether a module exposing permissions for the current entity type
    * should use entity-type level granularity, bundle level granularity or just

core/lib/Drupal/Core/Entity/Entity.php

@@ -181,6 +181,19 @@ class Entity implements IteratorAggregate, EntityInterface {
     return $uri;
   }
 
+  /**
+   * {@inheritdoc}
+   *
+   * Returns a list of URI relationships supported by this entity.
+   *
+   * @return array
+   *   An array of link relationships supported by this entity.
+   */
+  public function uriRelationships() {
+    $entity_info = $this->entityInfo();
+    return isset($entity_info['links']) ? array_keys($entity_info['links']) : array();
+  }
+
   /**
    * Implements \Drupal\Core\Entity\EntityInterface::get().
    */

core/lib/Drupal/Core/Entity/EntityBCDecorator.php

@@ -211,6 +211,13 @@ class EntityBCDecorator implements IteratorAggregate, EntityInterface {
     $this->decorated = clone $this->decorated;
   }
 
+  /**
+   * Forwards the call to the decorated entity.
+   */
+  public function uriRelationships() {
+    return $this->decorated->uriRelationships();
+  }
+
   /**
    * Forwards the call to the decorated entity.
    */
@@ -355,8 +362,8 @@ class EntityBCDecorator implements IteratorAggregate, EntityInterface {
   /**
    * Forwards the call to the decorated entity.
    */
-  public function uri() {
-    return $this->decorated->uri();
+  public function uri($rel = 'canonical') {
+    return $this->decorated->uri($rel);
   }
 
   /**

core/lib/Drupal/Core/Entity/EntityInterface.php

@@ -135,6 +135,14 @@ interface EntityInterface extends ComplexDataInterface, AccessibleInterface, Tra
    */
   public function uri();
 
+  /**
+   * Returns a list of URI relationships supported by this entity.
+   *
+   * @return array
+   *   An array of link relationships supported by this entity.
+   */
+  public function uriRelationships();
+
   /**
    * Saves an entity permanently.
    *

core/lib/Drupal/Core/Entity/EntityNG.php

@@ -73,6 +73,13 @@ class EntityNG extends Entity {
    */
   protected $fieldDefinitions;
 
+  /**
+   * Local cache for URI placeholder substitution values.
+   *
+   * @var array
+   */
+  protected $uriPlaceholderReplacements;
+
   /**
    * Overrides Entity::__construct().
    */
@@ -135,6 +142,61 @@ class EntityNG extends Entity {
     return $this->get('uuid')->value;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function uri($rel = 'canonical') {
+    $entity_info = $this->entityInfo();
+
+    $link_templates = isset($entity_info['links']) ? $entity_info['links'] : array();
+
+    if (isset($link_templates[$rel])) {
+      $template = $link_templates[$rel];
+      $replacements = $this->uriPlaceholderReplacements();
+      $uri['path'] = str_replace(array_keys($replacements), array_values($replacements), $template);
+
+      // @todo Remove this once http://drupal.org/node/1888424 is in and we can
+      //   move the BC handling of / vs. no-/ to the generator.
+      $uri['path'] = trim($uri['path'], '/');
+
+      // Pass the entity data to url() so that alter functions do not need to
+      // look up this entity again.
+      $uri['options']['entity_type'] = $this->entityType;
+      $uri['options']['entity'] = $this;
+      return $uri;
+    }
+
+    // For a canonical link (that is, a link to self), look up the stack for
+    // default logic. Other relationship types are not supported by parent
+    // classes.
+    if ($rel == 'canonical') {
+      return parent::uri();
+    }
+  }
+
+  /**
+   * Returns an array of placeholders for this entity.
+   *
+   * Individual entity classes may override this method to add additional
+   * placeholders if desired. If so, they should be sure to replicate the
+   * property caching logic.
+   *
+   * @return array
+   *   An array of URI placeholders.
+   */
+  protected function uriPlaceholderReplacements() {
+    if (empty($this->uriPlaceholderReplacements)) {
+      $this->uriPlaceholderReplacements = array(
+        '{entityType}' => $this->entityType(),
+        '{bundle}' => $this->bundle(),
+        '{id}' => $this->id(),
+        '{uuid}' => $this->uuid(),
+        '{' . $this->entityType() . '}' => $this->id(),
+      );
+    }
+    return $this->uriPlaceholderReplacements;
+  }
+
   /**
    * Implements \Drupal\Core\TypedData\ComplexDataInterface::get().
    */

core/modules/comment/comment.module

@@ -1568,10 +1568,11 @@ function template_preprocess_comment(&$variables) {
   }
 
   $uri = $comment->uri();
+  $permalink_uri = $comment->permalink();
   $uri['options'] += array('attributes' => array('class' => 'permalink', 'rel' => 'bookmark'));
 
   $variables['title'] = l($comment->subject->value, $uri['path'], $uri['options']);
-  $variables['permalink'] = l(t('Permalink'), $uri['path'], $uri['options']);
+  $variables['permalink'] = l(t('Permalink'), $permalink_uri['path'], $permalink_uri['options']);
   $variables['submitted'] = t('Submitted by !username on !datetime', array('!username' => $variables['author'], '!datetime' => $variables['created']));
 
   if ($comment->pid->target_id) {
@@ -1589,10 +1590,10 @@ function template_preprocess_comment(&$variables) {
     else {
       $variables['parent_changed'] = format_date($comment_parent->changed->value);
     }
-    $uri_parent = $comment_parent->uri();
-    $uri_parent['options'] += array('attributes' => array('class' => 'permalink', 'rel' => 'bookmark'));
-    $variables['parent_title'] = l($comment_parent->subject->value, $uri_parent['path'], $uri_parent['options']);
-    $variables['parent_permalink'] = l(t('Parent permalink'), $uri_parent['path'], $uri_parent['options']);
+    $permalink_uri_parent = $comment_parent->permalink();
+    $permalink_uri_parent['options'] += array('attributes' => array('class' => array('permalink'), 'rel' => 'bookmark'));
+    $variables['parent_title'] = l($comment_parent->subject->value, $permalink_uri_parent['path'], $permalink_uri_parent['options']);
+    $variables['parent_permalink'] = l(t('Parent permalink'), $permalink_uri_parent['path'], $permalink_uri_parent['options']);
     $variables['parent'] = t('In reply to !parent_title by !parent_username',
         array('!parent_username' => $variables['parent_author'], '!parent_title' => $variables['parent_title']));
   }

core/modules/comment/lib/Drupal/comment/CommentInterface.php

@@ -14,4 +14,13 @@ use Drupal\Core\Entity\ContentEntityInterface;
  */
 interface CommentInterface extends ContentEntityInterface {
 
+  /**
+   * Returns the permalink URL for this comment.
+   *
+   * @return array
+   *   An array containing the 'path' and 'options' keys used to build the URI
+   *   of the comment, and matching the signature of
+   *   UrlGenerator::generateFromPath().
+   */
+  public function permalink();
 }

core/modules/comment/lib/Drupal/comment/Plugin/Core/Entity/Comment.php

@@ -41,6 +41,10 @@ use Drupal\Core\Language\Language;
  *     "bundle" = "node_type",
  *     "label" = "subject",
  *     "uuid" = "uuid"
+ *   },
+ *   links = {
+ *     "canonical" = "/comment/{comment}",
+ *     "edit-form" = "/comment/{comment}/edit"
  *   }
  * )
  */
@@ -219,4 +223,15 @@ class Comment extends EntityNG implements CommentInterface {
   public function id() {
     return $this->get('cid')->value;
   }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function permalink() {
+
+    $url['path'] = 'node/' . $this->nid->value;
+    $url['options'] = array('fragment' => 'comment-' . $this->id());
+
+    return $url;
+  }
 }

core/modules/node/lib/Drupal/node/Plugin/Core/Entity/Node.php

@@ -48,7 +48,12 @@ use Drupal\node\NodeBCDecorator;
  *     "bundle" = "type"
  *   },
  *   route_base_path = "admin/structure/types/manage/{bundle}",
- *   permission_granularity = "bundle"
+ *   permission_granularity = "bundle",
+ *   links = {
+ *     "canonical" = "/node/{node}",
+ *     "edit-form" = "/node/{node}/edit",
+ *     "version-history" = "/node/{node}/revisions"
+ *   }
  * )
  */
 class Node extends EntityNG implements NodeInterface {

core/modules/node/node.module

@@ -2164,11 +2164,18 @@ function node_page_view(EntityInterface $node) {
   // of the active trail, and the link name becomes the page title.
   // Thus, we must explicitly set the page title to be the node title.
   drupal_set_title($node->label());
-  $uri = $node->uri();
-  // Set the node path as the canonical URL to prevent duplicate content.
-  drupal_add_html_head_link(array('rel' => 'canonical', 'href' => url($uri['path'], $uri['options'])), TRUE);
-  // Set the non-aliased path as a default shortlink.
-  drupal_add_html_head_link(array('rel' => 'shortlink', 'href' => url($uri['path'], array_merge($uri['options'], array('alias' => TRUE)))), TRUE);
+
+  foreach ($node->uriRelationships() as $rel) {
+    $uri = $node->uri($rel);
+    // Set the node path as the canonical URL to prevent duplicate content.
+    drupal_add_html_head_link(array('rel' => $rel, 'href' => url($uri['path'], $uri['options'])), TRUE);
+
+    if ($rel == 'canonical') {
+      // Set the non-aliased canonical path as a default shortlink.
+      drupal_add_html_head_link(array('rel' => 'shortlink', 'href' => url($uri['path'], array_merge($uri['options'], array('alias' => TRUE)))), TRUE);
+    }
+  }
+
   return node_show($node);
 }
 

core/modules/rdf/lib/Drupal/rdf/Tests/CommentAttributesTest.php

@@ -135,11 +135,11 @@ class CommentAttributesTest extends CommentTestBase {
     $this->drupalLogin($this->web_user);
     $comment_1 = $this->saveComment($this->node->nid, $this->web_user->uid);
 
-    $comment_1_uri = url('comment/' . $comment_1->id(), array('fragment' => 'comment-' . $comment_1->id(), 'absolute' => TRUE));
+    $comment_1_uri = url('comment/' . $comment_1->id(), array('absolute' => TRUE));
 
     // Posts a reply to the first comment.
     $comment_2 = $this->saveComment($this->node->nid, $this->web_user->uid, NULL, $comment_1->id());
-    $comment_2_uri = url('comment/' . $comment_2->id(), array('fragment' => 'comment-' . $comment_2->id(), 'absolute' => TRUE));
+    $comment_2_uri = url('comment/' . $comment_2->id(), array('absolute' => TRUE));
 
     $parser = new \EasyRdf_Parser_Rdfa();
     $graph = new \EasyRdf_Graph();
@@ -176,7 +176,8 @@ class CommentAttributesTest extends CommentTestBase {
    *   An array containing information about an anonymous user.
    */
   function _testBasicCommentRdfaMarkup($graph, $comment, $account = array()) {
-    $comment_uri = url('comment/' . $comment->id(), array('fragment' => 'comment-' . $comment->id(), 'absolute' => TRUE));
+    $uri = $comment->uri();
+    $comment_uri = url($uri['path'], $uri['options'] + array('absolute' => TRUE));
 
     // Comment type.
     $expected_value = array(
@@ -235,7 +236,12 @@ class CommentAttributesTest extends CommentTestBase {
     else {
       // The author is expected to be a blank node.
       $author_uri = $graph->get($comment_uri, '<http://rdfs.org/sioc/ns#has_creator>');
-      $this->assertTrue($author_uri->isBnode(), 'Comment relation to author found in RDF output (sioc:has_creator).');
+      if ($author_uri instanceof \EasyRdf_Resource) {
+        $this->assertTrue($author_uri->isBnode(), 'Comment relation to author found in RDF output (sioc:has_creator) and author is blank node.');
+      }
+      else {
+        $this->fail('Comment relation to author found in RDF output (sioc:has_creator).');
+      }
     }
 
     // Author name.

core/modules/rdf/rdf.module

@@ -419,7 +419,7 @@ function rdf_comment_load($comments) {
     $comment->rdf_data['date'] = rdf_rdfa_attributes($comment->rdf_mapping['created'], $comment->created->value);
     $comment->rdf_data['nid_uri'] = url('node/' . $comment->nid->target_id);
     if ($comment->pid->target_id) {
-      $comment->rdf_data['pid_uri'] = url('comment/' . $comment->pid->target_id, array('fragment' => 'comment-' . $comment->pid->target_id));
+      $comment->rdf_data['pid_uri'] = url('comment/' . $comment->pid->target_id);
     }
   }
 }

core/modules/taxonomy/lib/Drupal/taxonomy/Plugin/Core/Entity/Term.php

@@ -43,6 +43,10 @@ use Drupal\taxonomy\TermInterface;
  *   bundle_keys = {
  *     "bundle" = "vid"
  *   },
+ *   links = {
+ *     "canonical" = "/taxonomy/term/{taxonomy_term}",
+ *     "edit-form" = "/taxonomy/term/{taxonomy_term}/edit"
+ *   },
  *   menu_base_path = "taxonomy/term/%taxonomy_term",
  *   route_base_path = "admin/structure/taxonomy/manage/{bundle}",
  *   permission_granularity = "bundle"

core/modules/taxonomy/taxonomy.pages.inc

@@ -32,12 +32,16 @@ function taxonomy_term_page(Term $term) {
   drupal_set_breadcrumb($breadcrumb);
   drupal_add_feed('taxonomy/term/' . $term->id() . '/feed', 'RSS - ' . $term->label());
 
-  $uri = $term->uri();
+  foreach ($term->uriRelationships() as $rel) {
+    $uri = $term->uri($rel);
+    // Set the term path as the canonical URL to prevent duplicate content.
+    drupal_add_html_head_link(array('rel' => $rel, 'href' => url($uri['path'], $uri['options'])), TRUE);
 
-  // Set the term path as the canonical URL to prevent duplicate content.
-  drupal_add_html_head_link(array('rel' => 'canonical', 'href' => url($uri['path'], $uri['options'])), TRUE);
-  // Set the non-aliased path as a default shortlink.
-  drupal_add_html_head_link(array('rel' => 'shortlink', 'href' => url($uri['path'], array_merge($uri['options'], array('alias' => TRUE)))), TRUE);
+    if ($rel == 'canonical') {
+      // Set the non-aliased canonical path as a default shortlink.
+      drupal_add_html_head_link(array('rel' => 'shortlink', 'href' => url($uri['path'], array_merge($uri['options'], array('alias' => TRUE)))), TRUE);
+    }
+  }
 
   $build['taxonomy_terms'] = taxonomy_term_view_multiple(array($term->id() => $term));
   if ($nids = taxonomy_select_nodes($term->id(), TRUE, config('node.settings')->get('items_per_page'))) {

core/modules/user/lib/Drupal/user/Plugin/Core/Entity/User.php

@@ -41,6 +41,10 @@ use Drupal\Core\Language\Language;
  *   entity_keys = {
  *     "id" = "uid",
  *     "uuid" = "uuid"
+ *   },
+ *   links = {
+ *     "canonical" = "/user/{user}",
+ *     "edit-form" = "/user/{user}/edit"
  *   }
  * )
  */

core/modules/views_ui/lib/Drupal/views_ui/ViewUI.php

@@ -1135,4 +1135,13 @@ class ViewUI implements ViewStorageInterface {
   public function onChange($property_name) {
     $this->storage->onChange($property_name);
   }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function uriRelationships() {
+    return $this->storage->uriRelationships();
+  }
+
+
 }