【问题标题】:"flask.cli.NoAppException" while running flask app运行烧瓶应用程序时出现“flask.cli.NoAppException”
【发布时间】:2020-04-16 06:52:46
【问题描述】:

我对 python 开发相当陌生,对烧瓶一无所知,我被分配了一个使用烧瓶开发的项目。经过几周的工作,我现在能够解决所有依赖项,并且项目现在已成功编译。但是当我使用flask run 运行项目然后在浏览器中输入url 时,它会抛出“flask.cli.NoAppException”。我怎样才能运行我这样尝试过的项目。

  1. 设置 FLASK_APP=init.py
  2. 设置 FLASK_ENV=开发
  3. 烧瓶运行

    • 服务 Flask 应用“init.py”(延迟加载)
    • 环境:发展
    • 调试模式:开启
    • 使用 stat 重启
    • 调试器已激活!
    • 调试器 PIN:202-733-235
    • http://127.0.0.1:5000/上运行(按CTRL+C退出)

这里是引用

"FLASK_APP=myappnam:name to specify one.
Traceback (most recent call last)

    File "C:\Program Files\Python38\Lib\site-packages\flask\_compat.py", line 39, in reraise

    raise value

    File "C:\Program Files\Python38\Lib\site-packages\flask\cli.py", line 97, in find_best_app

    raise NoAppException(

    flask.cli.NoAppException: Failed to find Flask application or factory in module "myappnam". Use "FLASK_APP=myappnam:name to specify one.

The debugger caught an exception in your WSGI application. You can now look at the traceback which led to the error.

To switch between the interactive traceback and the plaintext one, you can click on the "Traceback" headline. From the text traceback you can also create a paste of it. For code execution mouse-over the frame you want to debug and click on the console icon on the right side.

You can execute arbitrary Python code in the stack frames and there are some extra helpers available for introspection:

    dump() shows all variables in the frame
    dump(obj) dumps all that's known about the object

这是我的 --init--.py 文件

import os
import logging
import gevent
import datetime
import rollbar

from gevent.queue import Queue
from gevent.event import AsyncResult
import zmq.green as zmq

from werkzeug.contrib.fixers import ProxyFix

# Greens the postgress connector
try:
    import psycogreen.gevent
    psycogreen.gevent.patch_psycopg()
except ImportError:
    pass

from rauth.service import OAuth2Service

from flask import Flask, Request
from flask_sqlalchemy import SQLAlchemy
from flask_bcrypt import Bcrypt
from flask_login import LoginManager, current_user
from flask_assets import Environment
from flask_uploads import UploadSet, configure_uploads, IMAGES

from app.util import setup_logging
from app.exceptions import TimeoutError, BackendError
import app.exceptions


flask_app = None

# Have to use an actor pattern because we cannot allow more than one request to
# be pending at a time.
class Backend(gevent.Greenlet):
    def __init__(self):
        super(Backend, self).__init__()

        self.inbox = Queue()
        self.zmq_context = zmq.Context()
        self.zmq_socket = None
        self.init_socket()

    def init_socket(self):
        zmq_socket = self.zmq_socket
        if zmq_socket is not None:
            zmq_socket.close(0)

        zmq_socket = self.zmq_context.socket(zmq.REQ)
        zmq_socket.connect(flask_app.config["SERVER_ZMQ_URI"])
        self.zmq_socket = zmq_socket

    def process(self, request):
        zmq_socket = self.zmq_socket

        poller = zmq.Poller()
        poller.register(zmq_socket, zmq.POLLIN)

        zmq_socket.send_json({
            "command": request["command"],
            "arguments": request["arguments"]
        })
        sockets = dict(poller.poll(10 * 1000))

        if zmq_socket not in sockets:
            self.init_socket()
            result = request["result"]
            result.set_exception(TimeoutError("The request to the backend timed out."))
            return

        received = zmq_socket.recv_json()

        result = request["result"]
        if received["success"]:
            result.set(received["result"])
        else:
            result.set_exception(BackendError(received["result"]))

    def _run(self):
        while True:
            self.process(self.inbox.get())            

    def send(self, command, **kwargs):
        result = AsyncResult()
        self.inbox.put({
            "command": command,
            "arguments": kwargs,
            "result": result
        })
        return result.get()


class RollbarRequest(Request):
    @property
    def rollbar_person(self):
        if current_user.is_anonymous:
            return {
                "id": 0, 
                "username": "anonymous"
            }
        return {
            "id": current_user.id,
            "username": current_user.name,
            "email": current_user.email_address
        }


def create_app(*args, **kwargs):
    global flask_app
    global l

    app_mode = os.environ.get("APP_MODE")

    assert app_mode is not None, "APP_MODE environment variable must be set"

    flask_app = Flask(__name__)
    flask_app.request_class = RollbarRequest
    flask_app.config.from_object("config.mode_{}".format(app_mode))
    flask_app.config["APP_MODE"] = app_mode

    setup_logging(flask_app.config["LOGGING_LEVEL"])

    l = logging.getLogger(__name__)
    l.info("starting in mode {}".format(app_mode))

    if not flask_app.config["DEBUG"]:
        rollbar.init(
            flask_app.config["ROLLBAR_API_KEY"],
            app_mode,
            allow_logging_basic_config=False
        )

    flask_app.jinja_env.globals.update(
        current_year=lambda: datetime.datetime.now().year
    )

    # Have to do this so that redirects work in proxy mode behind NGINX.
    if not flask_app.debug:
        flask_app.wsgi_app = ProxyFix(flask_app.wsgi_app)

    flask_app.db = SQLAlchemy(flask_app)

    flask_app.bcrypt = Bcrypt(flask_app)
    flask_app.assets = Environment(flask_app)

    flask_app.images = UploadSet("images", IMAGES)
    configure_uploads(flask_app, flask_app.images)

    flask_app.photos = UploadSet("photos", IMAGES)
    configure_uploads(flask_app, flask_app.photos)

    login_manager = LoginManager()
    login_manager.login_view = "signin"
    login_manager.login_message_category = "alert"  # Need newer release of Flask-Login for this to work.
    login_manager.init_app(flask_app)

    flask_app.facebook = OAuth2Service(
        name="facebook",
        base_url="https://graph.facebook.com/v2.8/",
        client_id=flask_app.config["FACEBOOK_CLIENT_ID"],
        client_secret=flask_app.config["FACEBOOK_CLIENT_SECRET"]
    )

    from app import views
    from app import models
    from app import commands

    flask_app.backend = Backend()
    flask_app.backend.start()

    app.exceptions.register(flask_app)

    return flask_app

这是我的项目结构 我正在使用 pycharm 和寡妇 10。

【问题讨论】:

    标签: python python-3.x flask


    【解决方案1】:

    在您的 create_app 函数中,您可能不想使用 global 关键字来进行应用程序的后期初始化。

    在您提供的示例中,从不调用 create_app 函数,因此从不创建应用实例。比较常见的使用create_app函数如下:

    def create_app():
        app = flask.Flask(__name__)
        # do some setup
        return app
    
    app = create_app()
    

    应用实例也应称为app,而不是flask_app。当然,您可以随意调用它,但默认情况下,flask 会查找 app。要指定您自己的更改 FLASK_APP=__init__.pyFLASK_APP=__init__:flask_app

    【讨论】:

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