烧瓶AttributeError:模块对象没有属性'app‘
烧瓶AttributeError:模块对象没有属性'app‘
提问于 2019-04-16 12:33:36
我是一个新的酒瓶，我有下面的导入相关的AttributeError时，flask run在flask_lab文件夹。
任何帮助都将不胜感激。
工作目录：
flask_lab
├── __init__.py
├── Pipfile
├── Pipfile.lock
├── README.md
├── tmp
│ ├── __init__.py
│ └── test.py
└── app.pyflask_lab/app.py:
import os
import click
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
import flask_lab.tmp.test.demo
app = Flask(__name__)
prefix = 'sqlite:////'
app.config['SQLALCHEMY_DATABASE_URI'] = prefix + os.path.join(app.root_path, 'data.db')
db = SQLAlchemy(app)
class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(20))
flask_lab.tmp.test.demo()flask_lab/tmp/test.py:
import flask_lab.app
print(flask_lab.app.db)
def demo():
print('yeah!')错误：
Traceback (most recent call last):
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/bin/flask", line 10, in <module>
sys.exit(main())
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/lib/python3.6/site-packages/flask/cli.py", line 894, in main
cli.main(args=args, prog_name=name)
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/lib/python3.6/site-packages/flask/cli.py", line 557, in main
return super(FlaskGroup, self).main(*args, **kwargs)
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/lib/python3.6/site-packages/click/core.py", line 717, in main
rv = self.invoke(ctx)
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/lib/python3.6/site-packages/click/core.py", line 1137, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/lib/python3.6/site-packages/click/core.py", line 956, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/lib/python3.6/site-packages/click/core.py", line 555, in invoke
return callback(*args, **kwargs)
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/lib/python3.6/site-packages/click/decorators.py", line 64, in new_func
return ctx.invoke(f, obj, *args, **kwargs)
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/lib/python3.6/site-packages/click/core.py", line 555, in invoke
return callback(*args, **kwargs)
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/lib/python3.6/site-packages/flask/cli.py", line 767, in run_command
app = DispatchingApp(info.load_app, use_eager_loading=eager_loading)
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/lib/python3.6/site-packages/flask/cli.py", line 293, in __init__
self._load_unlocked()
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/lib/python3.6/site-packages/flask/cli.py", line 317, in _load_unlocked
self._app = rv = self.loader()
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/lib/python3.6/site-packages/flask/cli.py", line 377, in load_app
raise_if_not_found=False)
File "/home/huafeng/.local/share/virtualenvs/flask_lab-x_qc9OjH/lib/python3.6/site-packages/flask/cli.py", line 235, in locate_app
__import__(module_name)
File "/home/huafeng/Desktop/flask_lab/app.py", line 7, in <module>
import flask_lab.tmp.test.demo
File "/home/huafeng/Desktop/flask_lab/tmp/test.py", line 3, in <module>
print(flask_lab.app.db)
AttributeError: module 'flask_lab' has no attribute 'app'有人抱怨堆叠过多的代码和不够的细节.更多的话，更多的话..。
回答 1
Stack Overflow用户
回答已采纳
发布于 2019-04-16 13:08:21
在解释app.py时，如果python解释器遇到一行import flask_lab.tmp.test.demo，那么它将立即开始解释tmp/test.py。但是tmp/test.py再次导入flask_lab。
此时，由于解释器已经遇到flask_lab，它将开始在该命名空间中搜索app。但直到那条线才到达。由于在模块中定义tmp.test之前已经导入了app，所以还没有flask_lab.app，因此出现了错误。
如果您直接调用了tmp.test，那么您也会遇到一个循环导入错误。
因此，出路是避免循环导入场景。将db对象移动到单独的模块，并在这两个模块中调用它。烧瓶-SQLAlchemy提供了一个名为init_app的方法，用于这种用例。
让我们创建一个名为公共的模块，它将包含公共变量。
烧瓶实验室/公共实验室
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()烧瓶实验室/app.py：
import os
import click
from flask import Flask
from .common import db
from .tmp.test import demo
class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(20))
app = Flask(__name__)
prefix = 'sqlite:////'
app.config['SQLALCHEMY_DATABASE_URI'] = prefix + os.path.join(app.root_path, 'data.db')
db.init_app(app)
demo()烧瓶实验室/tmp/test.py：
from .common import db
print(db)
def demo():
print('yeah!')请注意，我还将flask_lab导入替换为相对导入。它们更干净。包内的代码应避免在导入中使用包名。这样，如果稍后更改包名，就可以这样做，而不必更改内部的所有代码。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/55708257
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