我正在测试Flask应用程序，收到“在应用程序上下文之外工作”错误。我的文件目录如下：

api
    app.py
    __init__.py
    models
        __init__.py
        user.py
    resources
        __init__.py
        deals.py
        stores.py
    common
        __init__.py
        calculations.py
        decorators.py

我的app.py文件如下所示：

import os
from flask import Flask, jsonify, url_for, redirect, request, g, current_app
from flask_pymongo import PyMongo
from flask_restful import Api, Resource
from flask_httpauth import HTTPTokenAuth
from flask.ext.sqlalchemy import SQLAlchemy
from flask.ext.httpauth import HTTPBasicAuth

from resources.deals import Deals
from resources.stores import Stores

from models.user import User

USERDBFILE=os.path.join(os.path.join(os.path.dirname(os.path.realpath(__file__)),'database'),'db.sqlite')

#Deals database
app = Flask(__name__)
app.config["MONGO_DBNAME"] = "database"
mongo = PyMongo(app,config_prefix='MONGO')
app.db = mongo

#User database
app.config['SECRET_KEY'] = 'SECRET KEY'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///db.sqlite'
app.config['SQLALCHEMY_COMMIT_ON_TEARDOWN'] = True
app.dbuser = SQLAlchemy(app)

#App url
app.APP_URL = "http://127.0.0.1:5000"

#Setup authorization
auth = HTTPTokenAuth(scheme='Token')

#Setup the app
api = Api(app)
api.add_resource(Deals, '/deals', '/Deals/<string:type>/<string:id>',endpoint="dealType")
api.add_resource(Stores, '/stores', '/Stores/<string:type>/<string:id>',endpoint="type")

if __name__ == "__main__":
    if not os.path.exists(USERDBFILE):
        app.dbuser.create_all()
    app.run(debug=True)

我的users.py文件如下所示：

from flask import current_app
import os
from flask import Flask, abort, request, jsonify, g, url_for
from flask.ext.sqlalchemy import SQLAlchemy
from flask.ext.httpauth import HTTPBasicAuth
from passlib.apps import custom_app_context as pwd_context
from itsdangerous import (TimedJSONWebSignatureSerializer
                          as Serializer, BadSignature, SignatureExpired)

class User(current_app.dbuser.Model):
    __tablename__ = 'user_api'
    id = current_app.dbuser.Column(current_app.dbuser.Integer,primary_key=True)
    date_created = current_app.dbuser.Column(current_app.dbuser.DateTime,default=current_app.dbuser.func.current_timestamp())
    date_modified = current_app.dbuser.Column(current_app.dbuser.DateTime,default=current_app.dbuser.func.current_timestamp(),
                                      onupdate=current_app.dbuser.func.current_timestamp())
    # User Name
    name = current_app.dbuser.Column(current_app.dbuser.String(128),nullable=False)
    # Identification Data: email & password
    email = current_app.dbuser.Column(current_app.dbuser.String(128),nullable=False,unique=True)
    password = current_app.dbuser.Column(current_app.dbuser.String(192),nullable=False)
    company = current_app.dbuser.Column(current_app.dbuser.String(128),nullable=False,unique=True)
    # Authorization Data: role & status
    role = current_app.dbuser.Column(current_app.dbuser.String(32),nullable=False,default='user')
    status = current_app.dbuser.Column(current_app.dbuser.Boolean,nullable=False,default=True)
    hourly_limit = current_app.dbuser.Column(current_app.dbuser.Integer,nullable=False,default=100)
    daily_limit = current_app.dbuser.Column(current_app.dbuser.Integer,nullable=False,default=2400)
    monthly_limit = current_app.dbuser.Column(current_app.dbuser.Integer,nullable=False,default=2400)
    admin = current_app.dbuser.Column(current_app.dbuser.Boolean,nullable=False,default=True)

    def hash_password(self, password):
        self.password_hash = pwd_context.encrypt(password)

    def verify_password(self, password):
        return pwd_context.verify(password, self.password_hash)

    def generate_auth_token(self, expiration=600):
        s = Serializer(current_app.config['SECRET_KEY'], expires_in=expiration)
        return s.dumps({'id': self.id})

    @staticmethod
    def verify_auth_token(token):
        s = Serializer(current_app.config['SECRET_KEY'])
        try:
            data = s.loads(token)
        except SignatureExpired:
            return None    # valid token, but expired
        except BadSignature:
            return None    # invalid token
        user = User.query.get(data['id'])
        return user

我使用以下命令运行www.example.com所在目录中的文件app.py

python app.py

但它返回以下错误：

File "app.py", line 13, in <module>
    from models.user import User
  File "/Users/toby/api/api/models/user.py", line 10, in <module>
    class User(current_app.dbuser.Model):
  File "/Users/toby/api/venv/lib/python3.4/site-packages/werkzeug/local.py", line 343, in __getattr__
    return getattr(self._get_current_object(), name)
  File "/Users/toby/api/venv/lib/python3.4/site-packages/werkzeug/local.py", line 302, in _get_current_object
    return self.__local()
  File "/Users/toby/api/venv/lib/python3.4/site-packages/flask/globals.py", line 34, in _find_app
    raise RuntimeError('working outside of application context')
RuntimeError: working outside of application context

如果我将www.example.com文件的内容移动user.py到app.py文件中，并将继承从current_app.dbuser.Model更改为app.dbuser.Model，那么看起来工作正常。有人知道我做错了什么吗？