diff --git a/library/think/Model.php b/library/think/Model.php
index e5a107f8..02cb6854 100644
--- a/library/think/Model.php
+++ b/library/think/Model.php
@@ -629,6 +629,7 @@ abstract class Model implements \JsonSerializable, \ArrayAccess
 
         // 检测字段
         if (!empty($this->field)) {
+            $this->db();
             foreach ($this->data as $key => $val) {
                 if (!in_array($key, $this->field)) {
                     unset($this->data[$key]);