烧瓶，SQLAlchemy:KeyError:'SQLALCHEMY_TRACK_MODIFICATIONS' [英] Flask, SQLAlchemy : KeyError: 'SQLALCHEMY_TRACK_MODIFICATIONS'

问题描述

我正在尝试按照以下教程中的说明进行操作:

I am trying to follow the instructions from the following tutorial:

教程

我从以下存储库下载了代码:

I downloaded the code from the following repo:

回购

但是，当我在本地运行它并尝试向数据库添加内容时，出现以下错误:

However when I run it locally and try to add something to the database, I get the following error:

builtins.KeyError
KeyError: 'SQLALCHEMY_TRACK_MODIFICATIONS'

当我试图读取回溯时，我意识到即使我在配置文件中添加了一个变量 SQLALCHEMY_TRACK_MODIFICATIONS，一些 python 库文件也无法识别它的存在.

When I tried to read the traceback, I realised that even if I add a variable SQLALCHEMY_TRACK_MODIFICATIONS to the config file, some python library file is unable to recognise it exists.

看起来类似问题有另一个答案，但这更像是一个快速解决方案，而不是为什么会发生这种情况.

Looks like there is another answer to a similar question, but that was more like a quick fix, not why this is happening.

我想知道为什么会发生这种情况以及如何解决它.最好不要改变整个结构.

I would like to know why this is happening and how to fix it.Preferably without changing the whole structure.

非常感谢.

推荐答案

代码中有两个 app = Flask(__name__) 会导致这个问题.

Having two app = Flask(__name__) in the code can cause this problem.

这就是我的情况，我删除了一个并将其保留在应用程序文件夹的 __init__.py 中，它起作用了

That was my case, I removed one and kept the one in the app's folder's __init__.py, and it worked

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