Python 触发异常：'；非类型'；对象没有属性'；app&x27；

使用Python3和Flask获取错误

在下面显示的代码中，您会注意到我将端口定义为8080。将其定义为端口80在我拥有的另一个应用程序中运行良好，该应用程序为我家的植物浇水，并在动态网页上显示结果，但在这里，它因权限拒绝错误而崩溃。为什么，考虑到两者都是以完全相同的方式在Raspbian上使用相同的版本创建的

但这不是问题所在。真正的问题是为什么它在同一个应用程序中甚至不能保持一致

#!/usr/bin/python3
from flask import Flask, render_template, redirect, url_for
from imapclient import IMAPClient 
import email
import time 
import sys
import os
from concurrent.futures import ThreadPoolExecutor
executor = ThreadPoolExecutor(1) # number of executor
import logging 

logging.basicConfig(filename='/home/pi/mailbox_event.log',level=logging.WARNING)
HOSTNAME = 'imap.plus.net' 
USERNAME = 'megapower+rob' 
PASSWORD = 'aqp-hRM-2Nb-qh9'

MAILBOX = 'INBOX' 
NEWMAIL_OFFSET = 0 
MAIL_CHECK_FREQ = 10 #number of seconds for mail check

m1 = ""
m2 = ""
m3 = ""
m4 = ""

app = Flask(__name__)

def TimeNowIs():
    TimeNow = time.strftime('%d/%m/%Y at %H:%M:%S')
    return TimeNow

print("Hi" )
print("Mailbox here")
print("Just starting up")
logging.info("Mailbox App starting up")

def template(title = "Mail Display!", text = TimeNowIs(), m1 = " ", m2 = " ", m3 = " ", m4 = " "):
    text, m1, m2, m3, m4 = ""
    templateData = {
        'title' : title,
        'text' : text,
        'm1' : m1,
        'm2' : m2,
        'm3' : m3,
        'm4' : m4
        }
    return templateData

@app.route("/")

def main():
    text = TimeNowIs()
    m1 = "Hi"
    m2 = "Mailbox here"
    m3 = "Just starting up"
    m4 = "Going to check your mail"

    list_object = [text, m1, m2, m3, m4]
    return render_template('main.html', text_to_send = list_object)

def getmail():
    try:
        print("Logging in")
        server = IMAPClient(HOSTNAME, use_uid=True, ssl=False)
        server.login(USERNAME, PASSWORD)
        server.select_folder('INBOX', readonly=True)
    except:
        connected = False
        server = ""
        logging.warning('Logon failed')
        print("Logon failed")
    else:
        connected = True
        print("Logon succeeded")

        messages = server.search('UNSEEN')
        print("we have %d unread emails." % len(messages))

        for uid, message_data in server.fetch(messages, 'RFC822').items():
            email_message = email.message_from_bytes(message_data[b'RFC822'])
            m1 = (uid, email_message.get('From'), email_message.get('Subject')) 
            print(m1)

        text = TimeNowIs()
        m1 = "Well now"
        m2 = "I've checked your mail"
        m3 = "you should see something here"
        m4 = "that isn't the start up message"

        list_object = [text, m1, m2, m3, m4]

        print("Logging out")
        server.logout()
    return render_template('main.html', text_to_send = list_object)


def printmail():
    try:
        while True:
            os.system("clear")
            timeString = time.strftime('%d/%m/%Y at %H:%M:%S')
            print("Checking mail")
            print(timeString)
            getmail()

            print("Waiting")
            time.sleep(MAIL_CHECK_FREQ)

    except KeyboardInterrupt:
        print("Shutting down")
        logging.info('System closed by Ctrl-C')
        print("Goodbye")
        #os.system("sudo reboot")

    except Exception as e:
        logging.warning('Exception triggered: ' + str(e))
        print("Exception triggered: " + str(e))
#        os.system("sudo reboot")
    pass
    return

if __name__ == "__main__":
    executor.submit(printmail)
    app.run(host='0.0.0.0', port=8080, debug=True)

我在这里争取的是这样一个场景：printmail（）作为一个永久循环运行，除非被杀死或发生致命异常，该异常将被记录，然后Pi重新启动。您将从所附的图像中看到main（）正在运行，并且list_对象已写入网页

但是，当调用getmail（）时，m1会被写入终端，因此我知道我们在这方面没有问题，但是呈现模板失败，因为“NoneType”对象没有属性“app”

---

我想知道这是怎么回事，因为返回render_模板行，并且创建list_对象的代码与main（）中的代码相同。

Flask render_模板函数希望能够访问Flask应用程序上下文。 您可以在此处看到render_模板实现：

from.globals import\u app\u ctx\u stack

ctx=\u app\u ctx\u stack.top
ctx.app.update\u模板\u上下文（上下文）
返回渲染(
ctx.app.jinja\u环境获取或选择模板（模板名称或列表），
上下文
ctx.app，
)

您需要找到一种方法，使您的执行器线程能够访问flask localstack上下文