无法创建/打开 SQLite 数据库

Question

我正在尝试制作一个基本的Flask - SQLAlchemy应用程序。我不明白Flask factory系统如何与Flask- sqlalchemy一起工作。下面是我的__init__.py文件:

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
def create_db(app: Flask):
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///instance/pdfextractor.db'
db = SQLAlchemy(app)
from pdfextractor.models import FileModel
db.init_app(app)
db.create_all()
db.session.commit()
def create_app(test_config=None):
# create and configure the app
app = Flask(__name__, instance_relative_config=True)
if test_config is None:
# load the instance config, if it exists, when not testing
app.config.from_pyfile('config.py', silent=True)
else:
# load the test config if passed in
app.config.from_pyfile('config.py', silent=False)
app.config.update(test_config)
create_db(app)
from pdfextractor import router
app.register_blueprint(router.bp)
return app

一个异常的测试结果:RuntimeError No application found.

要么在视图函数中工作，要么推送应用程序上下文。看到flask-sqlalchemy.pocoo.org/contexts。

文件"pdfextractor/__init__.py"，第20行，在create_db db.create_all()

File "pdfextractor/__init__.py"，第42行，create_app create_db(app)

File FileModel.py:

import pdftotext
from datetime import datetime
from pathlib import Path
from flask import current_app as app
from shutil import copyfile
from flask_sqlalchemy import SQLAlchemy  
db = SQLAlchemy()
class FileModel(db.Model):
id = db.Column(db.Integer, primary_key=True)
content = db.Column(db.String(), unique=True, nullable=False)
datetime = db.Column(db.String(255), unique=True, nullable=False)
def __init__(self: object, content=None, datetime=None):
self.content = content
self.datetime = datetime
self._output_folder = Path(app.config['DATA_FOLDER'])
if False == self._output_folder.exists():
self._output_folder.mkdir()

def __repr__(self):
return '<File %r>' % (self.content, self.datetime)

非常感谢您的支持!

Answer 1

我已经用下面的代码修复了我的问题。谢谢你的帮助!

__init__ . py

from flask import Flask
def create_app(test_config=None):
# create and configure the app
app = Flask(__name__, instance_relative_config=True)
if test_config is None:
# load the instance config, if it exists, when not testing
app.config.from_pyfile('config.py', silent=True)
else:
# load the test config if passed in
app.config.from_pyfile('config.py', silent=False)
app.config.update(test_config)
from pdfextractor import router
app.register_blueprint(router.bp)
return app

FileModel.py

import pdftotext
from datetime import datetime
from pathlib import Path
from flask import current_app as app
from sqlalchemy import Column, Integer, String
from pdfextractor.common.base import Base
from pdfextractor.common.base import session_factory
class FileModel(Base):
__tablename__ = 'file'
id=Column(Integer, primary_key=True)
content=Column('content', String)
datetime=Column('datetime', String(255))
def __init__(self: object, content=None, datetime=None):
self.content = content
self.datetime = datetime
self._output_folder = Path(app.config['DATA_FOLDER'])
if False == self._output_folder.exists():
self._output_folder.mkdir()
def _persist(self, content: str, datetime: str):
session = session_factory()
self.content = str(content)
self.datetime = str(datetime)
session.add(self)
session.commit()
session.close()
def persist(self, filename: str):
today = datetime.today()
output_filepath = self._output_folder / Path('file_' + today.strftime("%Y-%m-%d-%H-%M-%S.%f") + '.txt')
if "pdf" == filename.rsplit('.', 1)[1].lower():
with open(filename, "rb") as f:
data = pdftotext.PDF(f)
with open(output_filepath, 'w') as f:
f.write('n'.join(data))
self._persist(''.join(data), output_filepath)
return 0
return -1

base.py

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
engine = create_engine('sqlite:///instance/pdfextractor.db')
# use session_factory() to get a new Session
_SessionFactory = sessionmaker(bind=engine)
Base = declarative_base()
def session_factory():
Base.metadata.create_all(engine)
return _SessionFactory()