调试代码出现错误from app import db

admin

PyDev console: starting.
Python 3.8.8 (tags/v3.8.8:024d805, Feb 19 2021, 13:18:16) [MSC v.1928 64 bit (AMD64)] on win32
from app import db
! B. r( v, N; f% h& x/ g! \6 `Traceback (most recent call last):
% U2 v. h: {, h2 V" b6 P  File "<input>", line 1, in <module>
" j5 j" H, I/ B' K* x) G" _  File "C:\Program Files\JetBrains\PyCharm Community Edition 2020.1.5\plugins\python-ce\helpers\pydev\_pydev_bundle\pydev_import_hook.py", line 21, in do_import
- h; t" a6 Y0 v6 ~  Q    module = self._system_import(name, *args, **kwargs)
ModuleNotFoundError: No module named 'app'

0 y! e, Y& }2 \8 O5 c2 w. @9 T
0 D5 a+ j' K. ^8 x
这里需要安装下app
+ ]0 L9 o5 w* o" H: y# ~: V0 g$ w
  ~. z2 o- @$ ]1 C$ Epip install app即可：解决问题。

admin

from app import db
Traceback (most recent call last):
  File "<input>", line 1, in <module>
ImportError: cannot import name 'db' from 'app' (C:\Users\xxxxx\testflask\venv\lib\site-packages\app\__init__.py)

admin

Traceback (most recent call last):
3 j: G! b& ?: ?" R4 c* i' z" {  File "<input>", line 1, in <module>
ImportError: cannot import name 'db' from 'app' (C:\Users\xxxxx\pythonProject\venv\lib\site-packages\app\__init__.py)

" h* H& X4 F0 P! P
遇到问题，我一直没有想过问题在哪里，为什么引入不了这个db
  O4 K( Y/ x- e; x在python console上执行时一直报错，但视频里却能正常，为什么？
. j% j  `; T0 I! L5 Z>>>from app import db
9 m! I+ ]( K  p4 ~Traceback (most recent call last):
  File "<input>", line 1, in <module>
/ V( d) p! e$ c# Y( sImportError: cannot import name 'db' from 'app' (C:\Users\xxxxx\pythonProject\pythonProject\venv\lib\site-packages\app\__init__.py)

) h0 a) t( M( q9 t# I6 M* f; S解决问题原因：
一次偶然的问题，一直测试，发现一个问题。我们的xxxx.py 这个flask文件的问题。
5 o. w6 F! d! O& x4 z我们取名叫什么，就用前面的名称  比如app.py就用app  完整的输入就是from app import db

4 p1 f* \8 M8 U但我这里的文件名称是appflask.py  那么我们这边就要在执行的时候，输入from appflask import db

>>>from appflask import db
& [. j9 H# b! E4 h( M" bC:\Users\xxxxx\venv\lib\site-packages\flask_sqlalchemy\__init__.py:834: FSADeprecationWarning: SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and will be disabled by default in the future.  Set it to True or False to suppress this warning.
0 r9 F; b: [! O  Q: P0 k6 V0 S  warnings.warn(FSADeprecationWarning(
. i5 R+ f+ A+ T: B8 X3 n
即可执行后面的db.create_all()等命令了。