update code

app/Entities/Attachment.php

@@ -0,0 +1,54 @@
+<?php
+
+namespace App\Entities;
+
+use Illuminate\Database\Eloquent\Model;
+use Prettus\Repository\Contracts\Transformable;
+use Prettus\Repository\Traits\TransformableTrait;
+
+/**
+ * Class Attachment.
+ *
+ * @package namespace App\Entities;
+ */
+class Attachment extends Model implements Transformable
+{
+    use TransformableTrait;
+
+    /**
+     * The attributes that are mass assignable.
+     *
+     * @var array
+     */
+    protected $fillable = [
+        'id',
+        'document_id',
+        'name',
+        'extension',
+        'size',
+        'path',
+        'downloads',
+    ];
+
+    /**
+     * All of the relationships to be touched.
+     *
+     * @var array
+     */
+    protected $touches = ['document'];
+
+    /**
+     * The attributes that should be cast to native types.
+     *
+     * @var array
+     */
+    protected $casts = [
+        'size' => 'decimal:2',
+        'downloads' => 'integer'
+    ];
+
+    public function document(){
+        return $this->belongsTo(Document::class);
+    }
+
+}