Python 如何修复将数据插入数据库时“TypeError:无法pickle线程.”本地对象“``的问题？

尝试将用户名和密码插入PostgreSQL数据库表时，出现以下错误：

TypeError
TypeError: can't pickle _thread._local objects

Traceback (most recent call last)
File "c:\users\alex\appdata\local\programs\python\python37-32\lib\site-packages\flask\app.py", line 2309, in __call__
return self.wsgi_app(environ, start_response)
File "c:\users\alex\appdata\local\programs\python\python37-32\lib\site-packages\flask\app.py", line 2295, in wsgi_app
response = self.handle_exception(e)
File "c:\users\alex\appdata\local\programs\python\python37-32\lib\site-packages\flask\app.py", line 1741, in handle_exception
reraise(exc_type, exc_value, tb)
File "c:\users\alex\appdata\local\programs\python\python37-32\lib\site-packages\flask\_compat.py", line 35, in reraise
raise value
File "c:\users\alex\appdata\local\programs\python\python37-32\lib\site-packages\flask\app.py", line 2292, in wsgi_app
response = self.full_dispatch_request()
File "c:\users\alex\appdata\local\programs\python\python37-32\lib\site-packages\flask\app.py", line 1816, in full_dispatch_request
return self.finalize_request(rv)
File "c:\users\alex\appdata\local\programs\python\python37-32\lib\site-packages\flask\app.py", line 1833, in finalize_request
response = self.process_response(response)
File "c:\users\alex\appdata\local\programs\python\python37-32\lib\site-packages\flask\app.py", line 2114, in process_response
self.session_interface.save_session(self, ctx.session, response)
File "c:\users\alex\appdata\local\programs\python\python37-32\lib\site-packages\flask_session\sessions.py", line 355, in save_session
total_seconds(app.permanent_session_lifetime))
File "c:\users\alex\appdata\local\programs\python\python37-32\lib\site-packages\werkzeug\contrib\cache.py", line 839, in set
pickle.dump(value, f, pickle.HIGHEST_PROTOCOL)
TypeError: can't pickle _thread._local objects

我不确定这意味着什么，但假设这是导致问题的代码：

user_id = db.execute("INSERT INTO users (username, password) VALUES(:username, :password)", {"username": username, "password": password})

if not user_id:
   return render_template("error.html", message="username already taken")

# stores users id
session["user_id"] = user_id

return redirect("/")

我的数据库有三个字段：用户名文本、密码文本和用户id整数

在我的python文件中，application.py使用以下代码将我的flask应用程序连接到数据库

# Set up database
engine = create_engine(os.getenv("DATABASE_URL"))
db = scoped_session(sessionmaker(bind=engine)) 

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我知道这已经很晚了，但为了防止有人仍然遇到这个问题，我想您忘记了包括fetchone或fetchall。因此，user\u id行应该读取user\u id=db.executes从username=：username、{username:username}.fetchone或类似的用户中选择user\u id，假设表中的每个用户都有唯一的用户id

类似地，我相信您会希望在尝试向表中插入行的任何行之后运行db.commit

---

会话行应该读取session[user\u id]=user\u id[0]。希望这能有所帮助。

请您提供更多信息，例如您使用的是哪个软件包以及如何连接到数据库。我已在python文件中添加了代码，该文件从堆栈跟踪连接到数据库。此错误似乎与flask会话包有关，而与您提供的数据库代码无关。我必须如何处理修复这个问题？我添加了更多的Python代码