Tkinter Python-根据Comboxbox的条件删除小部件

Question

I am trying to write a Python Tkinter program to display/remove a Label and Entry based on Combobox condition, it is working fine for display but for remove/hide it is not working.

def on_field_change(index, value, op):
    var_select_combo = box.current()
    serv_label = Label(frame1, text="Servive Name")
    E3 = Entry(frame1, bd=5)
    if var_select_combo == 1:
        serv_label.grid(row=3)
        E3.grid(row=3, column=1, pady=10)
    if var_select_combo == 0:
        serv_label.grid_forget()
        E3.grid_forget()

L3 = Label(frame1, text="Database")
L3.grid(row=0,pady=10)
box_value = StringVar()
box_value.trace('w',on_field_change)
box = ttk.Combobox(frame1, text="Database", textvariable=box_value,
                            state='readonly')
box['values'] = ('Teradata','Oracle')
box.current(0)
box.grid(column=1, row=0,pady=10)

Answer 1

You have to create widgets inside if and you have to assign them to global variables.

Now when you choose to remove you create second pair of widgets (because you create it before if ) and then you remove this second pair but first pair is still visible - but you don't have access to first pair because you didn't assign them to global variables.

You can also create widgets only once - at start - and later only show and hide it.

def on_field_change(index, value, op):
    var_select_combo = box.current()
    if var_select_combo == 1:
        serv_label.grid(row=3)
        E3.grid(row=3, column=1, pady=10)
    else:
        serv_label.grid_forget()
        E3.grid_forget()

# create at start assigned to global variables
serv_label = Label(frame1, text="Servive Name")
E3 = Entry(frame1, bd=5)