update code

app/Entities/Book.php

@@ -0,0 +1,63 @@
+<?php
+
+namespace App\Entities;
+
+use Illuminate\Database\Eloquent\Model;
+use Prettus\Repository\Contracts\Transformable;
+use Prettus\Repository\Traits\TransformableTrait;
+
+/**
+ * Class Book.
+ *
+ * @package namespace App\Entities;
+ */
+class Book extends Model implements Transformable
+{
+    use TransformableTrait;
+
+    /**
+     * The attributes that are mass assignable.
+     *
+     * @var array
+     */
+    protected $fillable = ['id', 'name'];
+
+    public $timestamps = false;
+
+    public $appends = ['unread', 'count'];
+
+    public const DI = 2;
+    public const DEN = 1;
+    public const NOIBO = 3;
+
+    public function documents(){
+        return $this->hasMany(Document::class);
+    }
+
+    public function isComeIn(){
+        return $this->id == self::DEN;
+    }
+
+    public function isComeOut(){
+        return $this->id == self::DI;
+    }
+
+    public function isPrivate(){
+        return $this->id == self::NOIBO;
+    }
+
+    public function getUnreadAttribute(){
+        return $this->documents()
+                    ->wherehas('receivers', function($query) { 
+                        return $query->where('id', auth()->id())->where('seen', false);
+                    })->count();
+    }
+
+    public function getCountAttribute(){
+        return $this->documents()
+                    ->wherehas('receivers', function($query) { 
+                        return $query->where('id', auth()->id());
+                    })->count();
+    }
+
+}