How to display ipywidgets.Dropdown without a value selected
No question anymore. The problem is older ipywidgets version behaviour that looks to be fixed in version 7.
The ipywidgets.Dropdown on its own picks up the first value out of the options list.
I would like to display the widget without a value selected.
The first value in the list is a pointless default that still needs to be reflected down the workflow path. I read a discussion where a developer went as far as adding empty string item into the list. That fixes the dropdown look (to some extent though as the placeholder attribute is still ignored) but adds a silly selectable empty item to the dropdown list. Adding dummy "None" item to the list is not much better solution.Setting value to None results in the "Invalid selection" exception.
I do not understand why the ipywidgets.Dropdown does not follow approach of the simpler widgets where empty value is allowed and placeholder text is dispalyed to prompt the user to select something.
Is there a way to make the widget selection not required? Some attribute setting I am not aware of? If that is impossible then what is the simplest possible workaround?
Answer
You can just set the dropdown value to None:
import ipywidgets as widgets
d = widgets.Dropdown(options=['hello', 'world'], value=None)
d
