Hi all,
I’m new to Plotly Dash so I wanted to run the examples on the documentation. I have some problems when runnning pattern-matching callbacks examples. This one is from “Simple example with ALL”:
import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output, State, MATCH, ALL
app = dash.Dash(__name__, suppress_callback_exceptions=True)
app.layout = html.Div([
html.Button("Add Filter", id="add-filter", n_clicks=0),
html.Div(id='dropdown-container', children=[]),
html.Div(id='dropdown-container-output')
])
@app.callback(
Output('dropdown-container', 'children'),
Input('add-filter', 'n_clicks'),
State('dropdown-container', 'children'))
def display_dropdowns(n_clicks, children):
new_dropdown = dcc.Dropdown(
id={
'type': 'filter-dropdown',
'index': n_clicks
},
options=[{'label': i, 'value': i} for i in ['NYC', 'MTL', 'LA', 'TOKYO']]
)
children.append(new_dropdown)
return children
@app.callback(
Output('dropdown-container-output', 'children'),
Input({'type': 'filter-dropdown', 'index': ALL}, 'value')
)
def display_output(values):
return html.Div([
html.Div('Dropdown {} = {}'.format(i + 1, value))
for (i, value) in enumerate(values)
])
if __name__ == '__main__':
app.run_server(debug=True)
Error output reads:
app.run_server(debug = True)
Dash is running on http://127.0.0.1:8050/
* Serving Flask app "__main__" (lazy loading)
* Environment: production
WARNING: This is a development server. Do not use it in a production deployment.
Use a production WSGI server instead.
* Debug mode: on
An exception has occurred, use %tb to see the full traceback.
SystemExit: 1
C:\Users\93cha\anaconda3\envs\srt\lib\site-packages\IPython\core\interactiveshell.py:3445: UserWarning: To exit: use 'exit', 'quit', or Ctrl-D.
warn("To exit: use 'exit', 'quit', or Ctrl-D.", stacklevel=1)
And when I call traceback:
%tb
Traceback (most recent call last):
File "<ipython-input-2-6f6fa5ce54d8>", line 1, in <module>
app.run_server(debug = True)
File "C:\Users\93cha\anaconda3\envs\srt\lib\site-packages\dash\dash.py", line 1717, in run_server
self.server.run(host=host, port=port, debug=debug, **flask_run_options)
File "C:\Users\93cha\anaconda3\envs\srt\lib\site-packages\flask\app.py", line 990, in run
run_simple(host, port, self, **options)
File "C:\Users\93cha\anaconda3\envs\srt\lib\site-packages\werkzeug\serving.py", line 1050, in run_simple
run_with_reloader(inner, extra_files, reloader_interval, reloader_type)
File "C:\Users\93cha\anaconda3\envs\srt\lib\site-packages\werkzeug\_reloader.py", line 339, in run_with_reloader
sys.exit(reloader.restart_with_reloader())
SystemExit: 1
I googled around and some people suggested deleting debug = True in app.run_server. I tried that and it ran, but I could then see only dropdowns and no outputs.
Layout I should see:
Layout that I see (no ouput text):
I tried googling some more, and other suggested there is a problem with the Reloader (I also don’t understand what reloader does) and instead I should run app.run_server(debug = Ture, use_reloader = False)
So I tried it out. The code ran, but when I went to the web browser there was error message:
So in short, I just copied the whole official example from the doc and did no adjustments, and still it couldn’t run. I only had problems with pattern-matching callbacks, all the other callbacks ran as expected.
I’m really grateful for any support! Thank you all!
!