想向greyli以及各位同学请教一个问题，我已经搜索过论坛和Google，但是无果
我的阅读进度在本书的5.3.3的第一个代码段
错误显示为
(flask-exercise-w9CIZiES) C:\Users\jnjga\flask-exercise\demos\database>flask shell
Usage: flask shell [OPTIONS]
Error: Could not import "app".
包依赖如下
(flask-exercise-w9CIZiES) C:\Users\jnjga\flask-exercise\demos\database>pipenv graph
Flask-SQLAlchemy==2.4.0
- Flask [required: >=0.10, installed: 1.1.1]
- click [required: >=5.1, installed: 7.0]
- itsdangerous [required: >=0.24, installed: 1.1.0]
- Jinja2 [required: >=2.10.1, installed: 2.10.1]
- MarkupSafe [required: >=0.23, installed: 1.1.1]
- Werkzeug [required: >=0.15, installed: 0.15.4]
- SQLAlchemy [required: >=0.8.0, installed: 1.3.8]
Flask-WTF==0.14.2
- Flask [required: Any, installed: 1.1.1]
- click [required: >=5.1, installed: 7.0]
- itsdangerous [required: >=0.24, installed: 1.1.0]
- Jinja2 [required: >=2.10.1, installed: 2.10.1]
- MarkupSafe [required: >=0.23, installed: 1.1.1]
- Werkzeug [required: >=0.15, installed: 0.15.4]
- WTForms [required: Any, installed: 2.2.1]
python-dotenv==0.10.3
该文件夹下的内容如下
(flask-exercise-w9CIZiES) C:\Users\jnjga\flask-exercise\demos\database>dir
驱动器 C 中的卷是 Windows
卷的序列号是 F62E-77FA
C:\Users\jnjga\flask-exercise\demos\database 的目录
2019/08/30 21:00 <DIR> .
2019/08/30 21:00 <DIR> ..
2019/08/30 21:00 13 .flaskenv
2019/08/30 20:56 423 app.py
2019/08/30 19:39 <DIR> templates
2019/08/30 20:05 <DIR> __pycache__
2 个文件 436 字节
4 个目录 55,455,485,952 可用字节
app.py内容如下
from flask import Flask,url_for,request
from flask_sqlalchemy import SQLAlchemy
import os
app=Flask(__name__)
db=SQLAlchemy(app)
#配置URI
app.config['SQLALCHEMY_DATABASE_URI']=os.getenv('DATABASE_URL','sqlite:///'+os.path.join(app.root_path,'data.db'))
app.config['SQLALCHEMY_TRACK_MODIFICATIONS']=False
class Note(db.Model):
id=db.Column(db.Integer,primary_key=True)
body=db.Column(db.Text)
这里是有app的为什么会显示无法导入app呢？
另外，请问如何进入pipenv安装的包依赖环境下进入python shell呢？（也即5.3.1中的第二个代码段）
十分感谢您的阅读，如果能帮忙解决此问题，不胜感激
更新
第二天我试图进入我自己仿照前几章所写的目录下，比如前两章我写的代码目录C:\Users\jnjga\flask-exercise\demos\basic（这部分代码之前使用各种命令是没有问题的），试图使用flask shell 仍显示 could not import “app”
如果我使用flask run 可以运行，但是访问localhost:5000时，会返回如下错误
Traceback (most recent call last):
File "c:\users\jnjga\.virtualenvs\flask-exercise-w9cizies\lib\site-packages\flask\cli.py", line 240, in locate_app
__import__(module_name)
ModuleNotFoundError: No module named 'app'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "c:\users\jnjga\.virtualenvs\flask-exercise-w9cizies\lib\site-packages\flask\cli.py", line 338, in __call__
self._flush_bg_loading_exception()
File "c:\users\jnjga\.virtualenvs\flask-exercise-w9cizies\lib\site-packages\flask\cli.py", line 326, in _flush_bg_loading_exception
reraise(*exc_info)
File "c:\users\jnjga\.virtualenvs\flask-exercise-w9cizies\lib\site-packages\flask\_compat.py", line 39, in reraise
raise value
File "c:\users\jnjga\.virtualenvs\flask-exercise-w9cizies\lib\site-packages\flask\cli.py", line 314, in _load_app
self._load_unlocked()
File "c:\users\jnjga\.virtualenvs\flask-exercise-w9cizies\lib\site-packages\flask\cli.py", line 330, in _load_unlocked
self._app = rv = self.loader()
File "c:\users\jnjga\.virtualenvs\flask-exercise-w9cizies\lib\site-packages\flask\cli.py", line 388, in load_app
app = locate_app(self, import_name, name)
File "c:\users\jnjga\.virtualenvs\flask-exercise-w9cizies\lib\site-packages\flask\cli.py", line 250, in locate_app
raise NoAppException('Could not import "{name}".'.format(name=module_name))
flask.cli.NoAppException: Could not import "app".
这是一个与上方相似的错误
我怀疑这是由于最近安装在pipenv环境中的包造成的，如flask-sqlalchemy，但我无法定位原因