How to get value from dependent combobox tkinter python?

Question

I'm able to select both the combo box successfully but to print the second dropdown box value, I got lost. Could somebody explain how to print the Table value from the 2nd drop down box.

Note: The two drop downs are dependabale.

import tkinter as tk
from tkinter import ttk
root = tk.Tk()
root.title("ETL")



Environment = ["UAT","ITEST","PROD"]

Tables = [["USER_UAT","IP_UAT"],
          ["USER_ITEST","IP_ITEST"],
          ["USER_PROD","IP_PROD"]]

envi= ttk.Combobox(root,width =37, value=(Environment))
envi.grid(row=3,column=1,columnspan=2, padx=10, pady=2, sticky='w')

def callback(eventObject):
    abc = eventObject.widget.get()
    en = envi.get()
    index=Environment.index(en)
    tab.config(values=Tables[index])

tab=ttk.Combobox(root, width=37)
tab.grid(row=4,column=1,columnspan=2, padx=10, pady=2, sticky='w')
tab.bind('<Button-1>', callback)

root.mainloop()

Answer 1

The most straightforward way is to add a separate event binding for each combobox. I changed the bindings from <Button-1> to <<ComboBoxSelect>> as this prevents the events from being fired every time a combobox is clicked - instead, events will only fire when a selection is actually made.

I also added some code to set the combobox default values as well as to update the value of the second combobobox whenever a selection is made in the first combobox.

import tkinter as tk
from tkinter import ttk

root = tk.Tk()
root.title('ETL')

environment = ['UAT', 'ITEST', 'PROD']
tables = [
    ['USER_UAT', 'IP_UAT'],
    ['USER_ITEST', 'IP_ITEST'],
    ['USER_PROD', 'IP_PROD'],
]


def populate_table_combobox(event):
    index = environment.index(env_combo.get())
    table_combo.config(values=tables[index])
    table_combo.current(0)  # update the 'table' selection when 'env' changes


def get_table_combo_value(event):
    print(table_combo.get())  # YOUR CODE HERE!


env_combo = ttk.Combobox(root, width=37, value=environment)
env_combo.current(0)  # set default value
env_combo.grid(row=3, column=1, columnspan=2, padx=10, pady=2, sticky='w')

table_combo = ttk.Combobox(root, width=37, values=tables[0])
table_combo.current(0)  # set default value
table_combo.grid(row=4, column=1, columnspan=2, padx=10, pady=2, sticky='w')

env_combo.bind('<<ComboBoxSelected>>', populate_table_combobox)
table_combo.bind('<<ComboBoxSelected>>', get_table_combo_value)

root.mainloop()