Clean up activity model

src/Core/Models/Activity.php

@@ -1,5 +1,18 @@
 <?php namespace Flarum\Core\Models;
 
+/**
+ * Models a user activity record in the database.
+ *
+ * Activity records show up in chronological order on a user's activity feed.
+ * They indicate when the user has done something, like making a new post. They
+ * can also be used to show any other relevant information on the user's
+ * activity feed, like if the user has been mentioned in another post.
+ *
+ * Each activity record has a *type*. The type determines how the record looks
+ * in the activity feed, and what *subject* is associated with it. For example,
+ * the 'posted' activity type represents that a user made a post. Its subject is
+ * a post, of which the ID is stored in the `subject_id` column.
+ */
 class Activity extends Model
 {
     /**
@@ -17,33 +30,48 @@ class Activity extends Model
     protected $dates = ['time'];
 
     /**
-     *
+     * A map of activity types and the model classes to use for their subjects.
+     * For example, the 'posted' activity type, which represents that a user
+     * made a post, has the subject model class 'Flarum\Core\Models\Post'.
      *
      * @var array
      */
-    protected static $subjects = [];
+    protected static $subjectModels = [];
 
     /**
-     * Unserialize the data attribute.
+     * When getting the data attribute, unserialize the JSON stored in the
+     * database into a plain array.
      *
-     * @param  string  $value
-     * @return string
+     * @param string $value
+     * @return mixed
      */
     public function getDataAttribute($value)
     {
-        return json_decode($value);
+        return json_decode($value, true);
     }
 
     /**
-     * Serialize the data attribute.
+     * When setting the data attribute, serialize it into JSON for storage in
+     * the database.
      *
-     * @param  string  $value
+     * @param mixed $value
      */
     public function setDataAttribute($value)
     {
         $this->attributes['data'] = json_encode($value);
     }
 
+    /**
+     * Get the subject model for this activity record by looking up its type in
+     * our subject model map.
+     *
+     * @return string|null
+     */
+    public function getSubjectModelAttribute()
+    {
+        return array_get(static::$subjectModels, $this->type);
+    }
+
     /**
      * Define the relationship with the activity's recipient.
      *
@@ -54,27 +82,35 @@ class Activity extends Model
         return $this->belongsTo('Flarum\Core\Models\User', 'user_id');
     }
 
+    /**
+     * Define the relationship with the activity's subject.
+     *
+     * @return \Illuminate\Database\Eloquent\Relations\MorphTo
+     */
     public function subject()
     {
-        return $this->mappedMorphTo(static::$subjects, 'subject', 'type', 'subject_id');
-    }
-
-    public static function getTypes()
-    {
-        return static::$subjects;
+        return $this->morphTo('subject', 'subjectModel', 'subject_id');
     }
 
     /**
-     * Register a notification type.
+     * Get the type-to-subject-model map.
      *
-     * @param  string $type
-     * @param  string $class
+     * @return array
+     */
+    public static function getSubjectModels()
+    {
+        return static::$subjectModels;
+    }
+
+    /**
+     * Set the subject model for the given activity type.
+     *
+     * @param string $type The activity type.
+     * @param string $class The class name of the subject model for that type.
      * @return void
      */
-    public static function registerType($class)
+    public static function setSubjectModel($type, $subjectModel)
     {
-        if ($subject = $class::getSubjectModel()) {
-            static::$subjects[$class::getType()] = $subject;
-        }
+        static::$subjectModels[$type] = $subjectModel;
     }
 }

src/Core/Repositories/EloquentActivityRepository.php

@@ -8,7 +8,7 @@ class EloquentActivityRepository implements ActivityRepositoryInterface
     public function findByUser($userId, User $viewer, $limit = null, $offset = 0, $type = null)
     {
         $query = Activity::where('user_id', $userId)
-            ->whereIn('type', array_keys(Activity::getTypes()))
+            ->whereIn('type', array_keys(Activity::getSubjectModels()))
             ->orderBy('time', 'desc')
             ->skip($offset)
             ->take($limit);

src/Extend/ActivityType.php

@@ -20,7 +20,7 @@ class ActivityType implements ExtenderInterface
     {
         $class = $this->class;
 
-        Activity::registerType($class);
+        Activity::setSubjectModel($class::getType(), $class::getSubjectModel());
 
         ActivitySerializer::$subjects[$class::getType()] = $this->serializer;
     }