增加Pivot对象parent属性

library/think/model/Pivot.php

@@ -16,13 +16,17 @@ use think\Model;
 class Pivot extends Model
 {
 
+    /** @var Model */
+    public $parent;
+
     /**
      * 构造函数
      * @access public
-     * @param array|object $data 数据
-     * @param string $table 中间数据表名
+     * @param Model        $parent
+     * @param array|object $data  数据
+     * @param string       $table 中间数据表名
      */
-    public function __construct($data = [], $table = '')
+    public function __construct(Model $parent, $data = [], $table = '')
     {
         if (is_object($data)) {
             $this->data = get_object_vars($data);
@@ -30,6 +34,8 @@ class Pivot extends Model
             $this->data = $data;
         }
 
+        $this->parent = $parent;
+
         $this->table = $table;
     }
 

library/think/model/relation/BelongsToMany.php

@@ -64,7 +64,7 @@ class BelongsToMany extends Relation
     protected function newPivot($data)
     {
         $pivot = $this->pivot ?: '\\think\\model\\Pivot';
-        return new $pivot($data, $this->middle);
+        return new $pivot($this->parent, $data, $this->middle);
     }
 
     /**