修正多对多关联的detach方法

Author: liu21st

src/model/relation/BelongsToMany.php

@@ -12,9 +12,9 @@
 namespace think\model\relation;
 
 use think\Collection;
+use think\Db;
 use think\db\Query;
 use think\Exception;
-use think\Db;
 use think\Model;
 use think\model\Pivot;
 use think\model\Relation;
@@ -69,13 +69,18 @@ public function pivot($pivot)
     /**
      * 实例化中间表模型
      * @param $data
-     * @return mixed
+     * @return Pivot
+     * @throws Exception
      */
     protected function newPivot($data = [])
     {
-        $pivot = $this->pivotName ?: '\\think\\model\\Pivot';
-
-        return new $pivot($this->parent, $data, $this->middle);
+        $class = $this->pivotName ?: '\\think\\model\\Pivot';
+        $pivot = new $class($this->parent, $data, $this->middle);
+        if ($pivot instanceof Pivot) {
+            return $pivot;
+        } else {
+            throw new Exception('pivot model must extends: \think\model\Pivot');
+        }
     }
 
     /**
@@ -530,7 +535,7 @@ public function detach($data = null, $relationDel = false)
         $pivot[$this->localKey] = $this->parent->$pk;
 
         if (isset($id)) {
-            $pivot[$this->foreignKey] = is_array($id) ? ['in', $id] : $id;
+            $pivot[$this->foreignKey] = is_array($id) ? [$this->foreignKey, 'in', $id] : [$this->foreignKey, '=', $id];
         }
 
         $this->pivot->where($pivot)->delete();