问题
I want to stop the user from pressing the "Submit" button for 30 seconds, after they have pushed it in the script below. How would I go about doing this? This is how my code looks currently:
import dash
from dash.dependencies import Input, Output, State
import dash_core_components as dcc
import dash_html_components as html
app = dash.Dash()
app.layout = html.Div([
dcc.Input(id='my-id', value='initial value', type="text"),
html.Button('Submit', id='button'),
html.Div(id='my-div')
])
@app.callback(
Output(component_id='my-div', component_property='children'),
[Input('button', 'n_clicks')],
state=[State(component_id='my-id', component_property='value')]
)
def update_output_div(n_clicks, input_value):
return 'You\'ve entered "{}" and clicked {} times'.format(input_value, n_clicks)
if __name__ == '__main__':
app.run_server()
Does anyone know how I can stop users from pushing the button for 30 seconds?
Thank in advance.
EDIT 15/08/2018 9:30AM GMT RESPONSE TO stevepastelan:
import dash
from dash.dependencies import Input, Output, State
import dash_core_components as dcc
import dash_html_components as html
app = dash.Dash()
app.layout = html.Div([
dcc.Input(id='my-id', value='initial value', type="text"),
html.Button('Submit', id='button'),
html.Div([dcc.Interval(
id='interval-component',
interval=1 * 3000, # in milliseconds
n_intervals=0
)]),
html.Div(id='my-div')
])
@app.callback(
Output(component_id='my-div', component_property='children'),
[Input('button', 'n_clicks')], [Input('interval-component', 'n_intervals')],
state=[State(component_id='my-id', component_property='value')]
)
def update_output_div(n_clicks,n_intervals, input_value):
return 'You\'ve entered "{}" and clicked {} times'.format(input_value, n_clicks)
if __name__ == '__main__':
app.run_server()
EDIT 15/08/2018 16:22PM WROTE SIMPLER SCRIPT WITH THE AN EDITED CALLBACK BUT IT DOESNT WORK:
import dash
from dash.dependencies import Input, Output, State
import dash_core_components as dcc
import dash_html_components as html
app = dash.Dash()
app.layout = html.Div([
dcc.Input(id='my-id', value='initial value', type="text"),
html.Button('Submit', id='button'),
html.Div([dcc.Interval(
id='interval-component',
interval=1 * 3000, # in milliseconds
n_intervals=0
)]),
html.Div(id='my-div')
])
@app.callback(
Output(component_id='my-div', component_property='children'),
[Input('button', 'n_clicks')], [Input('interval-component', 'n_intervals')],
state=[State(component_id='my-id', component_property='value')]
)
def update_output_div(n_clicks,n_intervals, input_value):
return 'You\'ve entered "{}" and clicked {} times'.format(input_value, n_clicks)
if __name__ == '__main__':
app.run_server()
回答1:
Updated answer
Okay, I managed to implement my own suggestion, but it was not trivial and still has quirks.
Complicating factors were:
- Dash does not permit two callbacks to target the same
Output - There is no good way to track which
InputorEventtriggered your callback. Workarounds generally involve tracking the number of clicks per button (see https://github.com/plotly/dash-html-components/pull/37 as an example). - Disabling a timer via
disable=Trueormax_requests=0appears to be permanent. Once I stopped a timer in this way, I could not restart it with eitherdisable=Falseormax_requests=1000.
Issues:
- In this solution,
update_output_div()gets called twice -- but you can tell the difference between the two by measuring the number of button clicks to the previous count, so you can keep it from submitting your data twice. - Timeouts of less than 100ms won't work. I had to split the delay timer for my method to work, so I chose
100and(1000 * BUTTON_PRESS_LOCKOUT_SECONDS)-100as the two timer durations. In principle, you could split them evenly half and half. I don't know if there are any problems with using a low timeout when working over the network (I did my testing on localhost).
Inspiration drawn from:
- https://community.plot.ly/t/how-to-turn-off-interval-event/5565/3
- https://github.com/plotly/dash-recipes/blob/master/toggle-interval.py
import json
import datetime
import dash
from dash.dependencies import Input, Output, State, Event
import dash_core_components as dcc
import dash_html_components as html
BUTTON_PRESS_LOCKOUT_SECONDS = 10 # seconds
app = dash.Dash()
app.config['suppress_callback_exceptions']=True
def serve_layout():
return html.Div([
dcc.Input(id='my-id', value='initial value', type="text"),
html.Button('Submit', id='button'),
html.Div(
[
dcc.Interval(id='interval-component', disabled=True)
, dcc.Interval(id='interval-sync-component', disabled=True)
]
, id='interval-container'
),
html.Div("", id='my-div'),
html.Div(json.dumps({'n_clicks':0, 'n_previous_clicks':0}), id='local_data'),
html.Div('??', id='button-status'),
])
app.layout = serve_layout
# Track button clicks
@app.callback(
output=Output(component_id='local_data', component_property='children'),
inputs=[Input('button', 'n_clicks')],
state=[State('local_data', 'children')],
events=[Event('interval-sync-component', 'interval')]
)
def track_clicks(n_clicks, local_data_json):
if n_clicks is None:
n_clicks = 0
local_data = json.loads(local_data_json)
n_previous_clicks = local_data['n_clicks']
# Update local data with the new click data
local_data.update(**{'n_clicks': n_clicks, 'n_previous_clicks': n_previous_clicks})
# local_data.update(**{'n_clicks': n_clicks, 'n_previous_clicks': n_previous_clicks})
return json.dumps(local_data)
# When the button click count is updated, submit
@app.callback(
output=Output(component_id='my-div', component_property='children'),
inputs=[Input('local_data', 'children')],
state=[State(component_id='my-id', component_property='value'), State('my-div', 'children')]
)
def update_output_div(local_data_json, input_value, current_state):
local_data = json.loads(local_data_json)
n_clicks = local_data['n_clicks']
n_previous_clicks = local_data['n_previous_clicks']
# Real submit
if n_clicks > n_previous_clicks:
return 'You\'ve entered "{}" and clicked {} times ({})'.format(
input_value
, n_clicks if n_clicks is not None else 0
, datetime.datetime.now()
)
# Not a real submit, but function is called an extra time as a side effect of the timer nonsense below.
else:
return '*' + current_state
# Start (or stop) the timer
@app.callback(
output=Output('interval-container', 'children'),
inputs=[Input('local_data', 'children')],
state=[State('button', 'disabled')],
events=[Event('interval-component', 'interval')]
)
def start_timer(local_data_json, button_is_disabled):
local_data = json.loads(local_data_json)
n_clicks = local_data['n_clicks']
n_previous_clicks = local_data['n_previous_clicks']
children=[]
if n_clicks > n_previous_clicks:
sync_timer = dcc.Interval(
id='interval-sync-component',
interval=100, # in milliseconds
)
children.append(sync_timer)
if button_is_disabled:
main_timer = dcc.Interval(
id='interval-component',
interval=(1000 * BUTTON_PRESS_LOCKOUT_SECONDS)-100, # in milliseconds
)
children.append(main_timer)
return children
# Enable the button whenever the timer interval is triggered or disable it when the button is pressed
@app.callback(
output=Output('button', 'disabled'),
inputs=[Input('button', 'n_clicks')],
state=[State('local_data', 'children')],
events=[Event('interval-component', 'interval')]
)
def toggle_button_disabled_state(n_clicks, local_data_json):
local_data = json.loads(local_data_json)
# n_clicks = local_data['n_clicks']
if n_clicks is None:
n_clicks = 0
n_previous_clicks = local_data['n_previous_clicks']
# We got here via button click, so disable the button
if n_clicks > n_previous_clicks:
return True
# We got here via timer expiration, so enable the button
else:
return False # enable the button
# Report on the button status
@app.callback(
output=Output('button-status', 'children'),
inputs=[Input('button', 'disabled')]
)
def update_button_status(disabled):
if disabled:
return 'Disabled submit button for {} seconds'.format(BUTTON_PRESS_LOCKOUT_SECONDS)
else:
return 'Submit button enabled'
if __name__ == '__main__':
app.run_server()
Original answer
You can trigger actions to be taken on the page based on a timer using dash_core_components.Interval. There are some examples here: https://dash.plot.ly/live-updates
You could initialize your interval component with n_intervals = 0, and then make your submit button disable itself and set n_intervals = 1. Then write a callback on the interval that re-enables the button.
来源：https://stackoverflow.com/questions/51838853/disable-submit-button-for-30-seconds-in-python-dash