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Attribute Error: layout traverse

Dash
#1

I am new to plotly/Dash. When I run the code from the website tutorial Updates On Page Load,

import datetime

import dash
import dash_html_components as html

def serve_layout():
    return html.H1('The time is: ' + str(datetime.datetime.now()))

app = dash.Dash()
app.layout = serve_layout

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

I get the following error

for component in self.layout.traverse():
AttributeError: ‘function’ object has no attribute ‘traverse’

However if I do app.layout = serve_layout() then it works.

I searched the forum and found some discussion about redefining the app twice, but nothing regarding ‘function’ object. Any help is much appreciated.

Thanks a lot

#2

Could you try upgrading dash? There have been a few bugfixes about this lately.

#3

Thanks for the suggestion. Dash seems to be up to date 0.26.0, I upgraded the components nevertheless. But still same issue.

plotly 3.1.1
core components 0.27.2
dash renderer 0.13.2
html components 0.11.0

#4

Hi ddas!

Thanks for the report. This was an issue in the dash core library: https://github.com/plotly/dash/issues/334.

A fix for this was just released in dash==0.26.1. I tested this app and it should work, but let us know if you have any more problems with this example!

Best,
Ryan

1 Like
#5

thank you so much, it works now. Really appreciate this and the quick turnaround. many thanks.

1 Like
#6

I am also observing this with the above example shown. Here are my dash versions as shown in my Pipfile:

dash = “==0.26.2”
dash-html-components = “==0.11.0”
dash-core-components = “==0.28.0”
dash-renderer = “==0.13.1”
plotly = “*”

#7

Looks like this (https://github.com/plotly/dash/pull/336) is working with:
dash==0.26.3
dash-core-components==0.27.2

1 Like
#8

Thanks, works like a charm!

#9

Thanks, yes this is the solution. You do not need dash-core-components==0.27.2 though.

#10

Thanks @rnarren1 There was a comment in the PR discussion about an issue with dash-core-components==0.28.0 - not sure if that has been resolved, yet, but it probably doesn’t apply to this specific issue.