Drop down list dependent from another drop down tkinter

Question

I have one list with car brands in it and a second list with model names from these brands. I want to have two dropdown lists. First you select the brand and in the second dropdown you can select the model. But just models from the selected brand. I got the following code.

import tkinter as tk

brands = ["Bugatti","VW","Opel","Porsche"]
models = [["Veyron","Chiron"],
          ["Golf","Passat","Polo","Caddy"],
          ["Insignia","Corsa","Astra"],
          ["Taycan","Cayenne","911"]] 

root = tk.Tk()
canvas = tk.Canvas(root, height=500, width= 500, bg="white")
canvas.pack()

tkvar = tk.StringVar(root)
tkvar.set('Choose')

popupMenu1 = OptionMenu(canvas, tkvar, *brands)
popupMenu1.pack()

def change_dropdown(*args):

    print("Chosen brand " + tkvar.get())

    for i in range(len(brands)):
        if tkvar.get() == brands[i]:
            print(models[i])

tkvar.trace('w', change_dropdown)
root.mainloop()

How do i now create a second dropdown with the information from the list models. Thanks for your help.

Answer 1

You can use Combobox to make dependent dropdown list

import tkinter
from tkinter import ttk
root = tkinter.Tk()
''' 
widgets are added here 
'''
brands = ["Bugatti","VW","Opel","Porsche"]

models = [["Veyron","Chiron"],
          ["Golf","Passat","Polo","Caddy"],
          ["Insignia","Corsa","Astra"],
          ["Taycan","Cayenne","911"]]

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

def callback(eventObject):
    abc = eventObject.widget.get()
    car = car_brand.get()
    index=brands.index(car)
    car_model.config(values=models[index])

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

root.mainloop()

Answer 2

import tkinter as tk

brands = ["Bugatti","VW","Opel","Porsche"]
models = [["Veyron","Chiron"],
          ["Golf","Passat","Polo","Caddy"],
          ["Insignia","Corsa","Astra"],
          ["Taycan","Cayenne","911"]]

root = tk.Tk()
canvas = tk.Canvas(root, height=500, width= 500, bg="white")
canvas.pack()

tkvar = tk.StringVar(root)
tkvar.set('Choose')

tkvar2 = tk.StringVar(root)
tkvar2.set('Model')

popupMenu1 = tk.OptionMenu(canvas, tkvar, *brands)
popupMenu1.pack()


popupMenu2 = tk.OptionMenu(canvas, tkvar2, [])
popupMenu2.pack()

def change_dropdown(*args):

    print("Chosen brand " + tkvar.get())
    for i in range(len(brands)):
        if tkvar.get() == brands[i]:
            popupMenu2["menu"].delete(0, "end")
            for item in models[i]:
                   popupMenu2['menu'].add_command(label=item, command=tk._setit(tkvar2, item))


tkvar.trace('w', change_dropdown)
root.mainloop()