AttributeError：“ NoneType”对象没有属性“ _instantiate_plugins”（无法导入create_engine） [英] AttributeError: 'NoneType' object has no attribute '_instantiate_plugins' (Cannot import create_engine)

问题描述

import os

from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker

engine=create_engine(os.getenv("DATABASE_URL"))
db = scoped_session(sessionmaker(bind=engine))

def main():
    flights = db.execute("SELECT origin, destination, duration FROM flights").fetchall()
    for flight in flights:
        print(f"{flight.origin} to {flight.destination}, {flight.duration} minutes.")

if __name__ == "__main__":
    main()

回溯（最近一次通话最近）：
文件 list.py，第6行，在
engine = create_engine（os.getenv（ DATABASE_URL））中
文件 C： \用户\Aakash\AppData\本地\程序\Python\Python38-32\lib\站点包\sqlalchemy\engine__init __。py，
行479，在create_engine中
return strategy.create（* args，** kwargs）
文件 C：\Users\Aakash\AppData\Local\Programs\Python\Python38-32\lib \site-pa ckages\sqlalchemy\engine\strategies.py，第56行，在创建
插件= u._instantiate_plugins（kwargs）
AttributeError：'NoneType'对象没有属性'_instantiate_plugins'

Traceback (most recent call last): File "list.py", line 6, in engine=create_engine(os.getenv("DATABASE_URL")) File "C:\Users\Aakash\AppData\Local\Programs\Python\Python38-32\lib\site-packages\sqlalchemy\engine__init__.py", line 479, in create_engine return strategy.create(*args, **kwargs) File "C:\Users\Aakash\AppData\Local\Programs\Python\Python38-32\lib\site-packages\sqlalchemy\engine\strategies.py", line 56, in create plugins = u._instantiate_plugins(kwargs) AttributeError: 'NoneType' object has no attribute '_instantiate_plugins'

如果将我的代码更改为：

And if change my code to:

问题和追溯已在图片中。

推荐答案

只需将其用作url
postgresql：// username：password @ host：port / database
直接将这些值传递到您的 create_engine（ postgresql：// username： password @ host：port / database）

just use this as url "postgresql://username:password@host:port/database" directly pass these values inside your create_engine("postgresql://username:password@host:port/database")

我现在遇到了同样的问题。这对我有用。值得一提的是，在创建新用户和数据库并移动表之后，我完全得到了一个不同的错误。错误是'

I was having the same problem now its gone.That worked for me. Only thing important to mention is that I got a different error altogether after creating the new user and database and moving the tables. The error was '

''ModuleNotFoundError：没有名为'psycopg2'的模块'''

'' ModuleNotFoundError: No module named 'psycopg2' '''

并且该解决方案正在运行： pip3安装psycopg2-binary

and the solution was running: pip3 install psycopg2-binary

PS：URL详细信息以及您的详细信息。

PS: URL details with you details.

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