ipywidget Dropdown 'new' value contains multiple objects

Question

I am building some interactive graphs and am trying to build one with second dynamic dropdown based on the first.

def update_dropdown(change):
    global country_list
    global country_list2
    global drop2
    print(change.new)
    ##country_list2 = country_list.remove(change.new) <- Not working because of multiple values
    ##drop2.options = country_list2
    
country_list2 = country_list
drop1 = widgets.Dropdown(options=country_list, value='United States', description='Country:')
drop2 = widgets.Dropdown(options=country_list2, value='China', description='Country:')
drop1.observe(update_dropdown)
interactive(compare_country_graph, Country1=drop1, Country2=drop2, Column=widgets.Dropdown(options=column_list, value='GDP', description='Metric:'))

**Ouput:**
{'index': 189}
Uruguay
Uruguay
189
{}

The problem is, change.new is returning mutiple values and no matter how I try and spin it, I can't just get one value. I have tried lists, dictionaries, series, and arrays to no avail.

More code I have tried:

def update_dropdown(change):
    global country_list
    global country_list2
    global drop2
    global y
    global newword
    y= []
    for letter in str(change.new):
        if letter.isalpha():
            y.append(letter)
    
    new = ""
    for x in y:
        new += x 
        
    print(new)

**Output:**
index
Uruguay
Uruguay 

Does anyone know how I can access and get ONLY the country name from this dropdown?

Answer 1

You can simply specify names='value' in your observe function and you will get the result you want.

See code below as an example:

import ipywidgets as widgets

country_list=['Uruguay', 'France','United States','Brazil']

def update_dropdown(change):

    print(change.new)

drop1 = widgets.Dropdown(options=country_list, value='United States', description='Country:')
drop1.observe(update_dropdown,names='value')
display(drop1)

And the output gives: