修复统一下单解析微信返回缺 result_code 时 AttributeError，并记录微信原始错误。

Co-authored-by: Cursor <cursoragent@cursor.com>

dingdan/views.py

@@ -329,11 +329,19 @@ class CreateOrderView(APIView):
             # 解析返回的XML
             root = ET.fromstring(response.content)
 
-            return_code = root.find('return_code').text
-            result_code = root.find('result_code').text
+            def _xml_text(tag, default=''):
+                node = root.find(tag)
+                return node.text if node is not None and node.text is not None else default
+
+            return_code = _xml_text('return_code')
+            result_code = _xml_text('result_code')
 
             if return_code == 'SUCCESS' and result_code == 'SUCCESS':
-                prepay_id = root.find('prepay_id').text
+                prepay_id = _xml_text('prepay_id')
+                if not prepay_id:
+                    raise Exception(
+                        f"微信支付下单失败: 缺少 prepay_id, raw={response.content.decode('utf-8', errors='ignore')}"
+                    )
 
                 # 生成前端支付参数
                 timestamp = str(int(time.time()))
@@ -365,19 +373,18 @@ class CreateOrderView(APIView):
 
                 return result
             else:
-                # 获取详细的错误信息
-                err_code = root.find('err_code')
-                err_code_des = root.find('err_code_des')
-                return_msg = root.find('return_msg')
-
-                error_details = f"return_code: {return_code}, "
-                if err_code is not None:
-                    error_details += f"err_code: {err_code.text}, "
-                if err_code_des is not None:
-                    error_details += f"err_code_des: {err_code_des.text}, "
-                if return_msg is not None:
-                    error_details += f"return_msg: {return_msg.text}"
+                # 获取详细的错误信息（return_code 失败时往往没有 result_code）
+                err_code = _xml_text('err_code')
+                err_code_des = _xml_text('err_code_des')
+                return_msg = _xml_text('return_msg')
+                raw = response.content.decode('utf-8', errors='ignore')
 
+                error_details = (
+                    f"return_code={return_code}, result_code={result_code}, "
+                    f"err_code={err_code}, err_code_des={err_code_des}, "
+                    f"return_msg={return_msg}, mch_id={MCHID}, raw={raw}"
+                )
+                logger.error("微信支付统一下单失败: %s", error_details)
                 raise Exception(f"微信支付下单失败: {error_details}")
 
         except Exception as e: