/**
  * @return \yii\db\ActiveQuery
  */
 public function getStockin()
 {
     return $this->hasOne(Stockin::className(), ['id' => 'stockin_id']);
 }
 /**
  * @return \yii\db\ActiveQuery
  */
 public function getStockins()
 {
     return $this->hasMany(Stockin::className(), ['id' => 'stockin_id'])->viaTable('stockin_detail', ['product_id' => 'id']);
 }