Dropdown files list dependent from another dropdown folder list

The basic algorithm behind the code want can be split as follows:

• bind each option select signal of the first combobox to a function,
• that scans a directory and sets the available files to the second combobox.

Now, the important part for this operation is:

optmenu.bind("<<ComboboxSelected>>", onSelect)......def onSelect(event):    folder_name = filelist[event.widget.current()]    folder_path = os.path.join(folder, folder_name)    print(f"folder selected:{folder_name}, folder_path:{folder_path}, index:{event.widget.current()}")    global sub_files    sub_files = []    for f_name in os.listdir(folder_path):        sub_files.append(f_name)    print(sub_files)    optmenu1['values'] = sub_files  # set sub directories to combobox

The complete code:

from tkinter import *from functools import partialimport osimport tkinter as tkfrom tkinter import ttk# import tkinter as tkfrom tkinter import filedialog, messagebox, ttkimport pandas as pdimport webbrowserfrom webbrowser import open as openlinkimport urllibdef open(file_menu):    filename = file_menu.get()    open_in_browser_link = f"file://{os.path.join(folder, filename)}"    print(open_in_browser_link)    webbrowser.open(open_in_browser_link)def clear_data():    #    tv1.delete(*tv1.get_children())    return Nonedef onSelect(event):    folder_name = filelist[event.widget.current()]    folder_path = os.path.join(folder, folder_name)    print(f"folder selected:{folder_name}, folder_path:{folder_path}, index:{event.widget.current()}")    global sub_files    sub_files = []    for f_name in os.listdir(folder_path):        sub_files.append(f_name)    print(sub_files)    optmenu1['values'] = sub_files  # set sub directories to comboboxfolder = os.path.realpath(r'C:\Users\TestFile')sub_files = []# folder = os.path.realpath(r'./testing')filelist = [fname for fname in os.listdir(folder)]master = tk.Tk()master.geometry('1200x800')master.title('THB')# Frame for TreeViewframe0 = tk.LabelFrame(master, text="Chapter", background="light grey")frame0.place(height=500, width=1200, rely=0.0, relx=0.0)optmenu = ttk.Combobox(frame0, values=filelist, state='readonly')optmenu.pack()optmenu.set("Chapter")optmenu.bind("<<ComboboxSelected>>", onSelect)optmenu1 = ttk.Combobox(frame0, values=[], state='readonly')optmenu1.pack()optmenu1.set("SubChapter")button_select = tk.Button(frame0, text="Show Data",                          width=15,                          height=2,                          compound=tk.CENTER,                          command=partial(open, optmenu1))button_select.place(relx=0.5, rely=0.5)button_select.pack(side=tk.TOP)master.mainloop()

Now, this code, opens the C:\Users\TestFile folder, and scans each direcotry and sets to first combobox (optmenu).

Then, when you select any one option in optmenu, it calls the onSelect() function. This onSelect function, read all files available inside the folder selected in optmenu, and shows the available files in optmenu1.