DatePickerRange: set a maximum_nights like property

In my dash app, I need my user to select a time period (in days). For that, I’m using a DatePickerRange.

However, I want to limit the max duration of this period — i.e., I don’t want the user to be able to select more than 1 month.

I know that the DatePickerRange has a minimum_nights property, but I haven’t found any maximum_nights.
➥ What is the best way to set a max limit to the period the user can select?

(I can imagine something with two date pickers with cross callbacks, but this doesn’t seems very “clean”)

You could try to add a certain amount of days to the start_date property of the DatePicker.

Some code:

app.layout = html.Div([
                 id = 'datepicker',

@app.callback(Output('datepicker', 'max_date_allowed'),
             [Input('datepicker', 'start_date')])
def set_max_data(start_date):
    start = datetime.strptime(start_date, "%m/%d/%y")
    end_date = start + timedelta(days=30)
    return end_date


from datetime import datetime, timedelta

You are right, this works… except that when I set the start_date, the end_date calendar dialog opens ; yet without the max_date_allowed fully working: you cannot select a date beyond start_date + 30, but those days are not greyed out (as the dialog might have been rendered before the max_date_allowed rule kicked in.

If you close and re-open the dialog, it works as expected.

However, you can understand that current state is not satisfactory as first scenario is the most frequent to occur.

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