根据下拉菜单的选择更新的 Tkinter 窗口

Question

I want to make a GUI that updates once the choice in the dropdown menu is changed. The code below does this with a button, but the buttons and text that is called is not deleted every time the function is called.

Update window without an additional button

from tkinter import *

app = Tk()

options = [
    "  ",
    "Expences",
    "Birds",
]


clicked = StringVar()
clicked.set(options[0])  # default value


drop = OptionMenu(app, clicked, *options)
drop.pack()


def show():
    click = clicked.get()

    if click == "Expences":
        def Expences():
            b2 = Button(app, text="YESSSS!!!")
            b2.pack()

        Expences()

    elif click == "Birds":
        def Birds():
            a3 = Label(app, text="Maybe")
            a3.pack()

        Birds()

    else:
        return


b1 = Button(app, text = "Click", command = show)
b1.pack()

app.minsize(400, 450)
app.mainloop()

Answer 1

You can use command= in OptionsMenu to run function when it changes selection. Function will get selected value

import tkinter as tk

def show(click):
    if click == "Expences":
        b2 = tk.Button(app, text="YESSSS!!!")
        b2.pack()
    elif click == "Birds":
        a3 = tk.Label(app, text="Maybe")
        a3.pack()

# --- main ---

options = [
    "  ",
    "Expences",
    "Birds",
]

app = tk.Tk()

clicked = tk.StringVar()
clicked.set(options[0])  # default value

drop = tk.OptionMenu(app, clicked, *options, command=show)
drop.pack()

app.mainloop()

---

You can use trace() with StringVar() to check if it changed value

import tkinter as tk

def show(a, b, c):
    click = clicked.get()

    if click == "Expences":
        b2 = tk.Button(app, text="YESSSS!!!")
        b2.pack()
    elif click == "Birds":
        a3 = tk.Label(app, text="Maybe")
        a3.pack()

# --- main ---

options = [
    "  ",
    "Expences",
    "Birds",
]

app = tk.Tk()

clicked = tk.StringVar()
clicked.set(options[0])  # default value
clicked.trace('w', show)

drop = tk.OptionMenu(app, clicked, *options)
drop.pack()

app.mainloop()

---

Tkinter will not delete previous button or label. You would have to do it on your own. Or better create label and button at start but don't use pack() to show it . Later you can use pack() to show one of them and pack_forget() to remove other one.

import tkinter as tk

def show(a, b, c):

    click = clicked.get()

    if click == "Expences":
        b2.pack()
        a3.pack_forget()
    elif click == "Birds":
        a3.pack()
        b2.pack_forget()

# --- main ---

options = [
    "  ",
    "Expences",
    "Birds",
]

app = tk.Tk()

clicked = tk.StringVar()
clicked.set(options[0])  # default value
clicked.trace('w', show)

drop = tk.OptionMenu(app, clicked, *options)
drop.pack()

b2 = tk.Button(app, text="YESSSS!!!")
a3 = tk.Label(app, text="Maybe")

app.mainloop()