AttributeError：“NoneType”对象没有属性“traverse”答案

【问题标题】：AttributeError: 'NoneType' object has no attribute 'traverse'AttributeError：“NoneType”对象没有属性“traverse”
【发布时间】：2018-07-08 15:55:47
【问题描述】：

我目前正在构建一个 Flask 应用程序，我正在尝试在其中加载一个 Plotly Dash 应用程序。

我能够从下面的 stackoverflow 留言板上得到这么远，但是我认为我做的不对（可能忽略了什么？）

Running a Dash app within a Flask app

这里的任何帮助将不胜感激

这是我的 server.py 代码：

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_bootstrap import Bootstrap
from flask_mail import Mail
from flask_moment import Moment 
from flask_login import LoginManager
from flask_pagedown import PageDown 
from flask_migrate import Migrate, MigrateCommand
from flask_sslify import SSLify
import os

import dash
import flask

server = flask.Flask(__name__)
app = dash.Dash(__name__, server=server)

basedir = os.path.abspath(os.path.dirname(__file__))

Here is my views.py:

from flask import Flask, request, render_template, flash, redirect, 
session, url_for, g, jsonify, make_response
from services.email import send_invite_email, send_recover_email, 
send_password_was_changed_email
from werkzeug.datastructures import CombinedMultiDict
from werkzeug.utils import secure_filename
from app import server, app 
from app import db
from models import User, Post 
from forms import RegisterForm, LoginForm, ForgotForm, ProfileForm, 
ResetPassword, InviteForm, PostForm
from flask_mongoengine import MongoEngine
from flask_login import login_user, logout_user, current_user, 
login_required, LoginManager
import os
from flask_babel import Babel, lazy_gettext
from flask_uploads import UploadSet, IMAGES, configure_uploads
from flask_avatar import Avatar
from momentjs import momentjs
from flask_mail import Mail
from dash import Dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, State, Output
import pandas as pd
import plotly.graph_objs as go
from analysis import * 

df = pd.read_csv(

'/Users.../ds/total/main.csv')



@server.before_request
def before_request():
    g.user = current_user


@server.route('/index', methods=['GET','POST'])
def index():
    app.layout = html.Div([
    dcc.Graph(
    ..... [[more dash code]]

    ])

    app.layout = html.Div(children=[
          [[more dash code]]
    ])

这是我的 server.py：从应用导入服务器，应用 server.run(debug=True)

当我全部运行时，我得到：

Traceback (most recent call last):
File "/Users/..lib/python3.6/site-packages/flask/app.py", line 2292, in 
wsgi_app
response = self.full_dispatch_request()
File "/Users/lib/python3.6/site-packages/flask/app.py", line 1808, in 
full_dispatch_request
 self.try_trigger_before_first_request_functions()
 File "/Users/lib/python3.6/site-packages/flask/app.py", line 1855, in 
 try_trigger_before_first_request_functions
 func()
 File "/Users/lib/python3.6/site-packages/dash/dash.py", line 561, in 
_setup_server
self._generate_scripts_html()
File "/Users//lib/python3.6/site-packages/dash/dash.py", line 245, in 
_generate_scripts_html
self.scripts.get_all_scripts() +
File "/Users/lib/python3.6/site-packages/dash/resources.py", line 128, 
in get_all_scripts
return self._resources.get_all_resources()
 File "/Users/lib/python3.6/site-packages/dash/resources.py", line 57, 
in get_all_resources
self.get_inferred_resources() + self._resources
File "/Users//lib/python3.6/site-packages/dash/resources.py", line 86, 
in 
get_inferred_resources
for t in layout.traverse():
AttributeError: 'NoneType' object has no attribute 'traverse'

【问题讨论】：

@PRMoureu 给你（很抱歉没有将其包含在原件中）
乍一看，您需要为破折号app.layout = ... (doc) 定义一些布局。此外，在声明 app 和 server 之后，您还需要在某个时候导入 views.py

标签： python flask plotly-dash

【解决方案1】：

我在尝试运行我的 Dash 应用程序时遇到了同样的错误消息，感谢this thread，我修复了它。据说需要在Procfile中将app:server改为index:app.server。

我不确定它是否适用于你的情况，如果你甚至有一个 Procfile 文件，但我把它放在这里是为了与我处于相同情况的人。

【讨论】：