Implement Linkable.

phpunit.xml.dist

@@ -27,6 +27,7 @@
             <file>./src/Behavior.php</file>
             <file>./src/ComponentsTrait.php</file>
             <file>./src/ModelEvent.php</file>
+            <file>./src/Linkable.php</file>
         </blacklist>
     </filter>
     <logging>

src/ArrayableTrait.php

@@ -2,6 +2,7 @@
 namespace rock\components;
 
 use rock\helpers\ArrayHelper;
+use rock\helpers\Link;
 use rock\helpers\ObjectHelper;
 
 /**
@@ -112,9 +113,9 @@ public function toArray(array $only = [], array $exclude = [], array $expand = [
             $data[$field] = is_string($definition) ? $this->$definition : call_user_func($definition, $field, $this);
         }
 
-//        if ($this instanceof Linkable) {
-//            $data['_links'] = Link::serialize($this->getLinks());
-//        }
+        if ($this instanceof Linkable) {
+            $data['_links'] = Link::serialize($this->getLinks());
+        }
 
         return $recursive ? static::convert($data) : $data;
     }

src/Linkable.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace rock\components;
+
+
+/**
+ * Linkable is the interface that should be implemented by classes that typically represent locatable resources.
+ */
+interface Linkable
+{
+    /**
+     * Returns a list of links.
+     *
+     * Each link is either a URI or a {@see \rock\helpers\Link} object. The return value of this method should
+     * be an array whose keys are the relation names and values the corresponding links.
+     *
+     * If a relation name corresponds to multiple links, use an array to represent them.
+     *
+     * For example,
+     *
+     * ```php
+     * [
+     *     'self' => 'http://example.com/users/1',
+     *     'friends' => [
+     *         'http://example.com/users/2',
+     *         'http://example.com/users/3',
+     *     ],
+     * ]
+     * ```
+     *
+     * @return array the links
+     */
+    public function getLinks();
+}