(.venv) PS D:\pycharm\daima\fg\login_reg> python manage.py makemigrations Traceback (most recent call last): File "D:\pycharm\daima\fg\login_reg\manage.py", line 21, in <module> main() File "D:\pycharm\daima\fg\login_reg\manage.py", line 17, in main execute_from_command_line(sys.argv) File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\core\management\__init__.py", line 381, in execute_from_command_line utility.execute() File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\core\management\__init__.py", line 375, in execute self.fetch_command(subcommand).run_from_argv(self.argv) File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\core\management\base.py", line 323, in run_from_argv self.execute(*args, **cmd_options) File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\core\management\base.py", line 364, in execute output = self.handle(*args, **options) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\core\management\base.py", line 83, in wrapped res = handle_func(*args, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\core\management\commands\makemigrations.py", line 101, in handle loader.check_consistent_history(connection) File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\db\migrations\loader.py", line 283, in check_consistent_history applied = recorder.applied_migrations() ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\db\migrations\recorder.py", line 73, in applied_migrations if self.has_table(): ^^^^^^^^^^^^^^^^ File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\db\migrations\recorder.py", line 56, in has_table return self.Migration._meta.db_table in self.connection.introspection.table_names(self.connection.cursor()) ^^^^^^^^^^^^^^^^^^^^^^^^ File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\db\backends\base\base.py", line 256, in cursor return self._cursor() ^^^^^^^^^^^^^^ File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\db\backends\base\base.py", line 233, in _cursor self.ensure_connection() File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\db\backends\base\base.py", line 217, in ensure_connection self.connect() File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\db\backends\base\base.py", line 197, in connect self.init_connection_state() File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\db\backends\mysql\base.py", line 231, in init_connection_state if self.features.is_sql_auto_is_null_enabled: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\utils\functional.py", line 80, in __get__ res = instance.__dict__[self.name] = self.func(instance) ^^^^^^^^^^^^^^^^^^^ File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\db\backends\mysql\features.py", line 82, in is_sql_auto_is_null_enabled cursor.execute('SELECT @@SQL_AUTO_IS_NULL') File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\db\backends\utils.py", line 103, in execute sql = self.db.ops.last_executed_query(self.cursor, sql, params) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "D:\pycharm\daima\fg\.venv\Lib\site-packages\django\db\backends\mysql\operations.py", line 146, in last_executed_query query = query.decode(errors='replace') ^^^^^^^^^^^^ AttributeError: 'str' object has no attribute 'decode'. Did you mean: 'encode'?
时间: 2025-06-02 08:12:16 浏览: 38
### 解决 Django 项目中运行 `python manage.py makemigrations` 时出现的 `AttributeError: 'str' object has no attribute 'decode'` 问题
此错误通常与 Django 版本和数据库驱动程序之间的不兼容性有关。以下是详细的解决方案:
#### 错误原因分析
该错误的核心问题是 `last_executed_query` 方法尝试对一个字符串对象调用 `.decode()` 方法,而该对象已经是解码后的字符串[^2]。在较新的 Python 版本中(如 Python 3.6+),字符串默认为 Unicode 类型,因此无需再次解码。
#### 修改 `operations.py` 文件
可以通过修改 Django 的源代码来解决此问题。具体方法如下:
1. 找到 Django 安装目录下的 `django/db/backends/mysql/operations.py` 文件。
2. 修改 `last_executed_query` 方法的实现,确保不会对已解码的字符串再次调用 `.decode()`。修改后的代码如下:
```python
def last_executed_query(self, cursor, sql, params):
query = getattr(cursor, '_executed', None)
if query is not None:
return query # 直接返回查询字符串,不再尝试解码
return None
```
上述修改直接返回 `_executed` 属性值,避免了对字符串进行不必要的解码操作[^2]。
#### 替代解决方案:升级或降级 Django 版本
如果不想修改 Django 源代码,可以考虑调整 Django 或 MySQL 驱动程序的版本以确保兼容性。例如:
- 如果使用的是 Django 2.2,请确保安装的 MySQL 驱动程序(如 `mysqlclient`)版本与 Django 兼容。
- 尝试将 Django 升级到更高版本(如 Django 3.x),这些版本可能已经修复了相关问题。
可以通过以下命令升级 Django:
```bash
pip install --upgrade django
```
#### 替代解决方案:调整 `_executed` 查询逻辑
另一种方法是通过格式化参数来生成最终的 SQL 查询字符串,而不是依赖 `_executed` 属性。以下是修改后的代码示例:
```python
def last_executed_query(self, cursor, sql, params):
query = getattr(cursor, '_executed', None)
if query is not None:
if params is not None:
if isinstance(params, (tuple, list)):
formatted_params = tuple(repr(param) for param in params)
elif isinstance(params, dict):
formatted_params = tuple(repr(param) for param in params.values())
else:
raise TypeError("Unsupported params type: {}".format(type(params)))
query = query.replace('%s', '{}')
return smart_str(query.format(*formatted_params))
else:
return smart_str(query)
return None
```
上述代码通过替换占位符 `%s` 来生成最终的 SQL 查询字符串,从而避免了对 `_executed` 属性的直接依赖[^3]。
#### 确保 MySQL 驱动程序正确安装
确保已正确安装并配置 MySQL 驱动程序(如 `mysqlclient`)。可以通过以下命令安装:
```bash
pip install mysqlclient
```
如果在 Windows 系统上遇到安装问题,可以尝试使用 `pymysql` 作为替代方案。需要在项目的 `__init__.py` 文件中添加以下代码:
```python
import pymysql
pymysql.install_as_MySQLdb()
```
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