Played around with a new app structure

app/Activity/Models/Favourite.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace BookStack\Activity\Models;
+
+use BookStack\App\Model;
+use BookStack\Permissions\Models\JointPermission;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+use Illuminate\Database\Eloquent\Relations\MorphTo;
+
+class Favourite extends Model
+{
+    protected $fillable = ['user_id'];
+
+    /**
+     * Get the related model that can be favourited.
+     */
+    public function favouritable(): MorphTo
+    {
+        return $this->morphTo();
+    }
+
+    public function jointPermissions(): HasMany
+    {
+        return $this->hasMany(JointPermission::class, 'entity_id', 'favouritable_id')
+            ->whereColumn('favourites.favouritable_type', '=', 'joint_permissions.entity_type');
+    }
+}