Failed to find application object 'server' in 'app' - heroku

Question

I am trying to serve a Dash app using Heroku. I have 5 files in my app:
.gitignore
venv
*.pyc
.DS_Store
.env
app.py
import os
import dash
import dash_core_components as dcc
import dash_html_components as html
import plotly.graph_objs as go
import pandas as pd
# Read in the data
districts_change = pd.read_csv("https://github.com/thedatasleuth/New-York-Congressional-Districts/blob/master/districts_change.csv?raw=True")
df = districts_change.drop(['TOTAL'], axis=1)
# Get a list of all the districts
districts = districts_change['DISTRICT'].unique()
# Create the app
app = dash.Dash()
# Populate the layout with HTML and graph components
app.layout = html.Div([
html.H2("New York Congressional Districts"),
html.Div(
[
dcc.Dropdown(
id="DISTRICT",
options=[{
'label': 'District {}'.format(i),
'value': i
} for i in districts],
value='All Districts'),
],
style={'width': '25%',
'display': 'inline-block'}),
dcc.Graph(id='funnel-graph'),
])
# Add the callbacks to support the interactive componets
#app.callback(
dash.dependencies.Output('funnel-graph', 'figure'),
[dash.dependencies.Input('DISTRICT', 'value')])
def update_graph(Districts):
if Districts == "All Districts":
df_plot = df.copy()
else:
df_plot = df[df['DISTRICT'] == Districts]
trace1 = go.Bar(x=df_plot ['Year'], y=df_plot [('DEM')], name='DEM')
trace2 = go.Bar(x=df_plot ['Year'], y=df_plot [('REP')], name='REP')
trace3 = go.Bar(x=df_plot ['Year'], y=df_plot [('CON')], name='CON')
trace4 = go.Bar(x=df_plot ['Year'], y=df_plot [('WOR')], name='WOR')
trace5 = go.Bar(x=df_plot ['Year'], y=df_plot [('IND')], name='IND')
trace6 = go.Bar(x=df_plot ['Year'], y=df_plot [('GRE')], name='GRE')
trace7 = go.Bar(x=df_plot ['Year'], y=df_plot [('WEP')], name='WEP')
trace8 = go.Bar(x=df_plot ['Year'], y=df_plot [('REF')], name='REF')
trace9 = go.Bar(x=df_plot ['Year'], y=df_plot [('OTH')], name='OTH')
trace10 = go.Bar(x=df_plot ['Year'], y=df_plot [('BLANK')], name='BLANK')
return {
'data': [trace1, trace2, trace3, trace4, trace5,
trace6, trace7, trace8, trace9, trace10],
'layout':
go.Layout(
title='District {}'.format(Districts),
barmode='group')
}
if __name__ == '__main__':
app.server.run(debug=True)
Procfile
web: gunicorn app:server
requirements.txt
Flask==1.0.2
gunicorn==19.9.0
dash==0.26.5
dash-core-components==0.29.0
dash-html-components==0.12.0
dash-renderer==0.13.2
plotly==3.2.1
pandas==0.23.1
pandas-datareader==0.6.0
runtime.txt
python-3.6.6
I am able to build the app successfully in Heroku, however, I am unable to serve it properly, given this error message:
Failed to find application object 'server' in 'app'
What server is it talking about? Usually when I get this error I just add whatever is missing to the requirements.txt file.

Answer 1

I added: server = app.server right under app = dash.Dash()