Django：AttributeError: ‘str’ object has no attribute ‘decode’
Django配置了MySQL数据库的连接之后，第一次连接之前，需要对MySQL数据库做【迁移 / 同步】操作。
该步骤不一定会成功。
比如，如题所示的错误，具体如下：
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PS D:\PyCharm_data\django_me> .\venv\Scripts\python.exe manage.py migrate Traceback (most recent call last): File "manage.py", line 21, in <module> main() File "manage.py", line 17, in main execute_from_command_line(sys.argv) File "D:\PyCharm_data\django_me\venv\lib\site-packages\django\core\management\__init__.py", line 381, in execute_from_command_line utility.execute() File "D:\PyCharm_data\django_me\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_data\django_me\venv\lib\site-packages\django\core\management\base.py", line 323, in run_from_argv self.execute(*args, **cmd_options) File "D:\PyCharm_data\django_me\venv\lib\site-packages\django\core\management\base.py", line 361, in execute self.check() File "D:\PyCharm_data\django_me\venv\lib\site-packages\django\core\management\base.py", line 390, in check include_deployment_checks=include_deployment_checks, File "D:\PyCharm_data\django_me\venv\lib\site-packages\django\core\management\commands\migrate.py", line 64, in _run_checks issues = run_checks(tags=[Tags.database]) File "D:\PyCharm_data\django_me\venv\lib\site-packages\django\core\checks\registry.py", line 72, in run_checks new_errors = check(app_configs=app_configs) File "D:\PyCharm_data\django_me\venv\lib\site-packages\django\core\checks\database.py", line 10, in check_database_backends issues.extend(conn.validation.check(**kwargs)) File "D:\PyCharm_data\django_me\venv\lib\site-packages\django\db\backends\mysql\validation.py", line 9, in check issues.extend(self._check_sql_mode(**kwargs)) File "D:\PyCharm_data\django_me\venv\lib\site-packages\django\db\backends\mysql\validation.py", line 13, in _check_sql_mode with self.connection.cursor() as cursor: File "D:\PyCharm_data\django_me\venv\lib\site-packages\django\db\backends\base\base.py", line 256, in cursor return self._cursor() File "D:\PyCharm_data\django_me\venv\lib\site-packages\django\db\backends\base\base.py", line 233, in _cursor self.ensure_connection() File "D:\PyCharm_data\django_me\venv\lib\site-packages\django\db\backends\base\base.py", line 217, in ensure_connection self.connect() File "D:\PyCharm_data\django_me\venv\lib\site-packages\django\db\backends\base\base.py", line 197, in connect self.init_connection_state() File "D:\PyCharm_data\django_me\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_data\django_me\venv\lib\site-packages\django\utils\functional.py", line 80, in __get__ res = instance.__dict__[self.name] = self.func(instance) File "D:\PyCharm_data\django_me\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_data\django_me\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_data\django_me\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' PS D:\PyCharm_data\django_me> </module> |
以上问题，比较容易发生在【Python 3.x】的版本中。
在Python 3.x中，上面错误中提到的文件【D:\PyCharm_data\django_me\venv\lib\site-packages\django\db\backends\mysql\operations.py】的【query】已经不需要再用【decode】解码，而是可以直接使用了。
因此，Python 3.x中，对【query】执行【decode】操作就出错了。
解法：
对文件【D:\PyCharm_data\django_me\venv\lib\site-packages\django\db\backends\mysql\operations.py】指定行做出修改。
备份原文件：
修改：
然后就没问题了：
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PS D:\PyCharm_data\django_me> .\venv\Scripts\python.exe manage.py runserver Watching for file changes with StatReloader Performing system checks... System check identified no issues (0 silenced). April 09, 2019 - 13:40:01 Django version 2.2, using settings 'django_me.settings' Starting development server at http://127.0.0.1:8000/ Quit the server with CTRL-BREAK. |
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Done。
