Datatable 3.2.0 failing with: dash.dash.exceptions.NoLayoutException: Layout must be a dash component or a function that returns a dash component.

An upgrade broke datatables for my environment, and I haven’t been able to undo the break even after rolling back the update, completely uninstalling python and starting from scratch, etc. Any app with a datatable is failing with the following error:

Dash Version 0.35.2
Dash DataTable Version 3.2.0
Dash Core Components Version 0.43.0
Dash HTML Components Version 0.13.5
Pandas Version 0.24.0
Numpy Version 1.16.1
Plotly Version 3.5.0
cx_Oracle Version 12.2.0.1.0

Traceback

 (most recent call last):
  File "C:\Users\david\.spyder-py3\dataagg_Test_001.py", line 73, in <module>
    data=dataaggrun.to_dict("rows"),
  File "C:\Users\david\AppData\Roaming\Python\Python37\site-packages\dash\dash\dash.py", line 279, in layout
    ''
dash.dash.exceptions.NoLayoutException: Layout must be a dash component or a function that returns a dash component.

It appears to be looking for a layout component, but none is require for a datatable. I downgraded back to my original versions, but the issue persists. My simplified code is below:

import dash
import dash_table
import dash_core_components as dcc
import dash_html_components as html
import pandas as pd
import numpy as np
import plotly
import cx_Oracle

#... some stuff here

#Retrieve DATAAGGRUN records
dataaggrunhist where processname = \'DATA AGGREGATION\' and status = \'COMPLETE\') order by dataaggrunid desc'
dataaggrun_query = 'select * from dataaggrun where dataaggrunid =4 order by dataaggrunid desc'
dataaggrun = pd.read_sql(dataaggrun_query, con= db)

external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app = dash.Dash(__name__, external_stylesheets=external_stylesheets)

app.layout = html.Div([
    html.Div(id='dataaggrun-table-container'),
 
    dash_table.DataTable(
        id='dataaggrun-table',
        columns=[
            {"name": i, "id": i} for i in dataaggrun.columns
        ],
        data=dataaggrun.to_dict("rows"),
    ),
])

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

The code from the dash.py file being referenced is below:

    @layout.setter
    def layout(self, value):
        if (not isinstance(value, Component) and
                not isinstance(value, collections.Callable)):
            raise exceptions.NoLayoutException(
                ''
                'Layout must be a dash component '
                'or a function that returns '
                'a dash component.')

[anocella]

@davidghill I happen to be subscribed to this repo so I skimmed the email I got for this issue. You definitely shouldn’t need to install the SSL package, and as @Marc-Andre-Rivet pointed out what you’re trying to install is a Python2 package in a Python3 environment. Moreover, it is an old package. This is in the setup.py:

if (sys.version_info >= (2, 6, 0)):
    raise ValueError("This extension should not be used with "
                     + "Python 2.6 or later (already built in), "
                     + "and has not been tested with Python 2.3.4 "
                     + "or earlier.")

You may want to look at https://stackoverflow.com/questions/41328451/ssl-module-in-python-is-not-available-when-installing-package-with-pip3.

[Marc-Andre-Rivet]

Feels like the script ran against python2 and then against python3 (enforcing parentheses)?

As this seems to be more of an environmental issue, I think you’ll have better chances of finding a resolution to this issue by sharing it on the community forum (https://community.plot.ly/).