Question

Flask SQLAlchemy db.create_all(app = app) 无法设置属性。没有创建 database.db 文件。每次我尝试创建它都表明它无法设置属性。我在另一个应用程序中使用了相同的技术，但当时它有效。请帮我摆脱这个错误。我是烧瓶的新手。

这是我的init.py

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from os import path
from flask_login import LoginManager

# creating the object for database
db = SQLAlchemy()
DB_NAME = "database.db"


# for creating the app
def create_app():
    # initializing the app
    app = Flask(__name__)
    app.config['SECRET_KEY'] = "Any secret key"
    # initializing the data base
    app.config['SQLALCHEMY_DATABASE_URI'] = f'sqlite:///{DB_NAME}'
    # for debugging sql
    # app.config['SQLALCHEMY_ECHO'] = True
    db.init_app(app)

    # now for registering the blueprints
    from .views import views
    from .auth import auth

    app.register_blueprint(views , url_prefix='/')
    app.register_blueprint(auth , url_prefix='/')

    # for creating database
    # from .models import User , Room , Participant , Message
    from .models import User,Note
    create_database(app)
    
    return app


def create_database(app):
    # if the database does not exist then we will create it
    if not path.exists('website/'+DB_NAME):
        db.create_all(app = app)
        print('Database created')

create_database() def 不起作用

我的模型.py

from . import db
from flask_login import UserMixin
from sqlalchemy.sql import func





# The User will inherit database model and UserMixin . The UserMixin is for authentication
# purpose
class User(db.Model , UserMixin):
    id = db.Column(db.Integer , primary_key = True)
    email = db.Column(db.String(150) , unique = True)
    password = db.Column(db.String(150))
    firstname = db.Column(db.String(150))
    lastname = db.Column(db.String(150))
    # a sudo column in Note
    notes = db.relationship('Note')

    # def __repr__(self):
    #     print(f"<Post {self.firstname}>")


class Note(db.Model):
    id = db.Column(db.Integer , primary_key = True)
    data = db.Column(db.String(10000))
    date = db.Column(db.DateTime(timezone=True), default = func.now())
    user_id = db.Column(db.Integer , db.ForeignKey('user.id'))

main.py

from website import create_app

app = create_app()


if __name__ == '__main__':
    # This is a debugging server
    app.run(debug = True)

这是应用程序结构的图片： app structure

日志如下：在日志中它说无法设置该属性。我也尝试过手动构建数据库，但它不起作用

(venv) naheed@naheed-s15-x530un:~/Desktop/flask-chat-app-v2$ python main.py 
/home/naheed/Desktop/flask-chat-app-v2/venv/lib/python3.8/site-packages/flask_sqlalchemy/__init__.py:833: 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.
  warnings.warn(FSADeprecationWarning(
Traceback (most recent call last):
  File "main.py", line 3, in <module>
    app = create_app()
  File "/home/naheed/Desktop/flask-chat-app-v2/website/__init__.py", line 32, in create_app
    create_database(app)
  File "/home/naheed/Desktop/flask-chat-app-v2/website/__init__.py", line 40, in create_database
    db.create_all(app = app)
  File "/home/naheed/Desktop/flask-chat-app-v2/venv/lib/python3.8/site-packages/flask_sqlalchemy/__init__.py", line 1039, in create_all
    self._execute_for_all_tables(app, bind, 'create_all')
  File "/home/naheed/Desktop/flask-chat-app-v2/venv/lib/python3.8/site-packages/flask_sqlalchemy/__init__.py", line 1031, in _execute_for_all_tables
    op(bind=self.get_engine(app, bind), **extra)
  File "/home/naheed/Desktop/flask-chat-app-v2/venv/lib/python3.8/site-packages/flask_sqlalchemy/__init__.py", line 962, in get_engine
    return connector.get_engine()
  File "/home/naheed/Desktop/flask-chat-app-v2/venv/lib/python3.8/site-packages/flask_sqlalchemy/__init__.py", line 555, in get_engine
    options = self.get_options(sa_url, echo)
  File "/home/naheed/Desktop/flask-chat-app-v2/venv/lib/python3.8/site-packages/flask_sqlalchemy/__init__.py", line 570, in get_options
    self._sa.apply_driver_hacks(self._app, sa_url, options)
  File "/home/naheed/Desktop/flask-chat-app-v2/venv/lib/python3.8/site-packages/flask_sqlalchemy/__init__.py", line 914, in apply_driver_hacks
    sa_url.database = os.path.join(app.root_path, sa_url.database)
AttributeError: can't set attribute

Answer 1

添加以下导入：

from sqlalchemy import create_engine

然后在你的 create_app() 函数中初始化它：

def create_app():
    app = Flask(__name__)
    app.config['SECRET_KEY'] = 'Any secret key'
    # app.config['SQLALCHEMY_DATABASE_URI'] = f'sqlite:///{DB_NAME}'
    engine = create_engine('sqlite:///{DB_NAME}')
    db.init_app(app)

sqlalchemy 1.4 documentation

Answer 2

我已经通过降级 SQLAlchemy 解决了这个问题。由于某种原因，最新版本不起作用

<块引用>

pip 安装'SQLAlchemy<1.4.0'

Flask SQLAlchemy db.create_all(app = app) 无法设置属性

create_database() def 不起作用

2 个答案: