[FIXED] ipywidgets: Update one widget based on results from another

Issue

I am using widgets in IPython that allows the user to repeatedly search for a phrase and see the results (different titles) in another widget (a selection widget) and then select one of the results.

In short:

search_text = widgets.Text(description = 'Search') 
search_result = widgets.Select(description = 'Select table')

def search_action(sender):
    phrase = search_text.value
    df = search(phrase) # A function that returns the results in a pandas df
    titles = df['title'].tolist()
    search_result.options = titles

search_text.on_submit(search_action)

This used to work fine, but after updating to the latest version of ipywidgets (5.1.3 from 4.0.1) it seems like

search_selection.options = titles

Produce the following errors (one or both, it varies):

TraitError: Invalid selection
TypeError: 'list' object is not callable

It still works in the sense that the widget gets updated with the results based on the search from the other widget, but it gives an error.

What is the correct way of setting the options in one widget based on the results from another widget?

(edit: added more detailed error message)

Solution

You can hold notifications for during the assignment to options:

with search_result.hold_trait_notifications():
    search_result.options = titles

Thus:

search_text = widgets.Text(description = 'Search') 
search_result = widgets.Select(description = 'Select table')

def search_action(sender):
    phrase = search_text.value
    df = search(phrase) # A function that returns the results in a pandas df
    titles = df['title'].tolist()
    with search_result.hold_trait_notifications():
        search_result.options = titles

See hmelberg's explanation below

"The root of the error is that the widget also has a value property and the value may not be in the new list of options. Because of this, widget value may be "orphaned" for a short time and an error is produced."

Answered By - Dan Schien