Update ttk.Combobox values based on another combobox

Question

I have two comboboxes and I want to update the values of one based on the value in another box. Here is my code:

import tkinter as tk
import tkinter.ttk as ttk

def update_box(imagesbox, new_values):
    imagesbox["values"] = new_values

def update_combobox_data(imagesbox, filterbox):
    new_values = []
    if filterbox.get() == "Bilateral":
        new_values = ["Original", "Contours", "Bilateral", "Enhanced", "Greyscale", "Black and white"]
    if filterbox.get() == "Median":
        new_values = ["Original", "Contours", "Median", "Enhanced", "Greyscale", "Black and white"]
    elif filterbox.get() == "Gaussian":
        new_values = ["Original", "Contours", "Gaussian", "Enhanced", "Greyscale", "Black and white"]
    imagesbox.set("") 
    update_box(imagesbox, new_values)

def labelframe(root, text, row, col):
    label_frame = tk.LabelFrame(root, text=text)
    label_frame.grid(row=row, column=col, padx=15, pady=10)
    return label_frame

def label(root, text, row, col):
    lab = tk.Label(root, text=text)
    lab.grid(row=row, column=col, padx=15, pady=10)
    return lab

def combobox(root, values, row, col):
    box1 = ttk.Combobox(root, values=values, state="readonly")
    box1.grid(row=row, column=col, padx=15, pady=10)
    box1.set(values[0])
    return box1

def main():
    root = tk.Tk()
    root.geometry("500x300")
    frame = tk.Frame(root)
    frame.pack()

    labelframe1 = labelframe(frame, "Settings", 1, 0)
    label1 = label(labelframe1, "Choose filter", 0, 0)
    filters = ["Bilateral", "Median", "Gaussian"]
    filter_combobox = combobox(labelframe1, filters, 1, 0)
    label2 = label(labelframe1, "Image type", 0, 1)
    images = ["Original", "Contours", "Bilateral", "Enhanced", "Greyscale", "Black and white"]
    images_combobox = combobox(labelframe1, images, 1, 1)
    bind1 = lambda: update_combobox_data(images_combobox, filter_combobox)
    images_combobox.bind("<<ComboboxSelected>>", bind1)

    root.mainloop()

main()

When I choose filter, I expect the image type box to update so that the filter gets updated there. For example, if I choose Gaussian filter, image types should be Original, Contours, Gaussian, Enhanced, Greyscale and Black and white. However, the box is not updating. I found some kind of solution, and in my code I tried to make a similar implementation, but it does not work.

Also, if I change the image type, I get this strange error: TypeError: main.<locals>.<lambda>() takes 0 positional arguments but 1 was given. I tried to search from the web but I do not understand why this error appears. I found this answer, but my lambda function does not take any arguments so there shouldn't be a problem?

How could I fix these errors?

Answer 1

The following changes to your code works for me.

The problem dealt with binding event and wrong combobox call.

Binding some action to a function passes event So change update_combobox to include event

def update_combobox_data(event, imagesbox, filterbox)

Then change bind1 to include event

bind1 = lambda event: update_combobox_data(event, images_combobox, filter_combobox)

Also bind filter_combobox to bind1

filter_combobox.bind("<<ComboboxSelected>>", bind1)