RuntimeError: No application found. Either work inside a view function or push an application context

Question

我使用 YouTube 上的一些教程构建了一个 Flask Web 应用程序。在我尝试向数据库添加新的 table 之前，它一直运行良好。我在 models.py 中创建了 table class。但是当我尝试从 python 控制台 after 运行ning from myapp import db 运行 db.create_all() 时，我得到了这个错误:

RuntimeError: No application found. Either work inside a view function or push an application context.

我已经检查过类似的问题，但找不到明确的答案。每个人都希望对 Flask 有一定的熟练程度，而我显然还没有。这就是我在这里寻求帮助的原因。我认为问题在于导入的数据库对模型一无所知。我不知道如何让它知道模型中的 classes。请帮忙！

这是 myapp/init.py 文件的样子：

    #IMPORTING NECESSARY LIBRARIES TO CREATE USEFUL OBJECTS

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_bcrypt import Bcrypt
from flask_login import LoginManager
from flask_mail import Mail
from myapp.config import Config

# CREATING USEFUL OBJECTS FOR USAGE IN OUR APP
mail = Mail()
db = SQLAlchemy()
bcrypt = Bcrypt()
login_manager = LoginManager()
login_manager.login_view = 'users.login'
login_manager.login_message_category = 'info'


def create_app(config_class=Config):
    # creating app variable out of Flask class
    app = Flask(__name__) 
    app.config.from_object(Config)

    # CONNECTING USEFUL OBJECTS WITH FLASK OBJECT APP
    mail.init_app(app)
    db.init_app(app)
    bcrypt.init_app(app)
    login_manager.init_app(app)

    # ADDING ROUTES TO THE FLASK OBJECT APP
    from myapp.users.routes import users
    from myapp.posts.routes import posts
    from myapp.main.routes import main
    from myapp.errors.handlers import errors
    from myapp.finance.routes import finance_data

    app.register_blueprint(users)
    app.register_blueprint(posts)
    app.register_blueprint(main)
    app.register_blueprint(errors)
    app.register_blueprint(finance_data)

    return app

这是 myapp/models.py 文件的样子：

from myapp import db, login_manager
from datetime import datetime
from flask_login import UserMixin
from itsdangerous import TimedJSONWebSignatureSerializer as Serializer
from flask import current_app
import time

today = datetime.today()
datem = datetime(today.year, today.month, 1)

@login_manager.user_loader
def load_user(user_id):
    return User.query.get(int(user_id))


class User(db.Model, UserMixin):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(20), unique=True, nullable=False)
    email = db.Column(db.String(120), unique=True, nullable=False)
    image_file = db.Column(db.String(20), nullable=False, default='default.jpg')
    password = db.Column(db.String(60), nullable=False)
    posts = db.relationship('Post',backref='author', lazy=True)
    fin = db.relationship('Finance', backref='author', lazy=True)

    def __repr__(self):
        return f"User('{self.username}','{self.email}','{self.image_file}')"

    def get_reset_token(self, expires_sec=1800):
        s = Serializer(current_app.config['SECRET_KEY'], expires_sec)
        return s.dumps({'user_id':self.id}).decode('utf-8')

    @staticmethod
    def verify_reset_token(token):
        s = Serializer(current_app.config['SECRET_KEY'])    
        try:
            user_id = s.loads(token)['user_id']
        except:
            return None
        return User.query.get(user_id)

class Post(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(100), nullable=False)
    date_posted = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
    content = db.Column(db.Text, nullable=False)
    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
    def __repr__(self):
        return f"Post('{self.title}','{self.date_posted}')"


class Finance(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    month = db.Column(db.DateTime, nullable=False, default=datem)
    revenue = db.Column(db.Float, nullable=False,default=0)
    Other_income = db.Column(db.Float,nullable=False,default=0)
    total_income = db.Column(db.Float, nullable=False,default=0)
    cogs = db.Column(db.Float,nullable=False,default=0)
    gross_profit = db.Column(db.Float, nullable=False,default=0)
    sga_expenses = db.Column(db.Float,nullable=False,default=0)
    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)

    def __repr__(self):
        return f"Finance('{self.month}','{self.user_id}')"

这是 run.py 文件的样子：

from myapp import create_app

app = create_app()


if __name__ == '__main__':  
    app.run(debug=True)

Answer 1

你需要使用 app_context，在终端中尝试此操作，在 run.py 所在的文件夹中打开终端：

from myapp import create_app, db
app = create_app()
with app.app_context():
    db.create_all()

RuntimeError: No application found. Either work inside a view function or push an application context

RuntimeError: No application found. Either work inside a view function or push an application context

python

sqlalchemy

flask

flask-sqlalchemy