How to pass data between top levels in tkinter

问题

I am totally new to tkinter. I am trying to pass data between two windows. There is a button on root window. button press will open a top level. There are two entry fields and a submit button in on toplevel window. user can enter two number and submit. What i am trying to achieve is, pressing submit button should close the top level and result (sum) should be shown in the root window. How to pass entry field data to root window?

from tkinter import *
root= Tk()
root.geometry('600x400')
sum_var= StringVar()

def entry_Fn():
    level_1 = Toplevel(root)
    Label( level_1, text = "level one").pack()
    entry_1 =Entry(level_1)
    entry_1.pack()
    entry_2 =Entry(level_1)
    entry_2.pack()
    Button(level_1, text= "submit", command= submitBtn ).pack()

def submitBtn():
    val_1= entry_1.get()
    val_2= entry_2.get()
    sum_var.set(int(val_1)+ int(val_2))

Label(root, text = "Main window").pack()
Button(root, text= "To enter Data", command= entry_Fn).pack()
sum = Label(root, textvariable = sum_var)
sum.pack()

root.mainloop()

#result
val_1= entry_1.get()
NameError: name 'entry_1' is not defined

#shall I define some global variables?

回答1:

In this case, you don't have to declare global. Simply indent your submitBtn function inside entry_Fn:

def entry_Fn():
    level_1 = Toplevel(root)
    Label( level_1, text = "level one").pack()
    entry_1 = Entry(level_1)
    entry_1.pack()
    entry_2 = Entry(level_1)
    entry_2.pack()
    def submitBtn():
        val_1= entry_1.get()
        val_2= entry_2.get()
        sum_var.set(int(val_1)+ int(val_2))
        level_1.destroy()
    Button(level_1, text= "submit", command=submitBtn).pack()

But generally it is easier to make a class so you can avoid this kind of scope problems, like below:

from tkinter import *

class GUI(Tk):
    def __init__(self):
        super().__init__()
        self.geometry('600x400')
        self.sum_var= StringVar()
        Label(self, text="Main window").pack()
        Button(self, text="To enter Data", command=self.entry_Fn).pack()
        sum = Label(self, textvariable=self.sum_var)
        sum.pack()

    def entry_Fn(self):
        self.level_1 = Toplevel(self)
        Label(self.level_1, text = "level one").pack()
        self.entry_1 = Entry(self.level_1)
        self.entry_1.pack()
        self.entry_2 = Entry(self.level_1)
        self.entry_2.pack()
        Button(self.level_1, text="submit", command=self.submitBtn).pack()

    def submitBtn(self):
        val_1 = self.entry_1.get()
        val_2 = self.entry_2.get()
        self.sum_var.set(int(val_1)+ int(val_2))
        self.level_1.destroy()

root = GUI()

root.mainloop()

回答2:

For your case, you can simply pass the two entries to submitBtn() function:

def submitBtn(entry_1, entry_2):
    ....

Then update the command= for the submit button inside entry_Fn():

Button(level_1, text="submit", command=lambda: submitBtn(entry_1, enter_2)).pack()

回答3:

You can subclass tk.TopLevel, and use a tk.IntVar to transfer the data back to root:

import tkinter as tk


class EntryForm(tk.Toplevel):

    def __init__(self, master, sum_var):
        super().__init__(master)
        tk.Label(self, text="level one").pack()
        self.sum_var = sum_var
        self.entry_1 = tk.Entry(self)
        self.entry_1.pack()
        self.entry_2 = tk.Entry(self)
        self.entry_2.pack()
        tk.Button(self, text="submit", command=self.submitBtn).pack()

    def submitBtn(self):
        val_1 = self.entry_1.get()
        val_2 = self.entry_2.get()
        self.sum_var.set(int(val_1) + int(val_2))
        self.destroy()

def spawn_entry_popup():
    EntryForm(root, sum_var)

root= tk.Tk()
root.geometry('600x400')
sum_var = tk.IntVar()
tk.Label(root, text = "Main window").pack()
tk.Button(root, text= "To enter Data", command=spawn_entry_popup).pack()
sum_label = tk.Label(root, textvariable=sum_var)
sum_label.pack()

root.mainloop()

You can also place your app inside a class:

import tkinter as tk


class EntryForm(tk.Toplevel):

    def __init__(self, master, sum_var):
        super().__init__(master)
        tk.Label(self, text="level one").pack()
        self.sum_var = sum_var
        self.entry_1 = tk.Entry(self)
        self.entry_1.pack()
        self.entry_2 = tk.Entry(self)
        self.entry_2.pack()
        tk.Button(self, text="submit", command=self.submitBtn).pack()

    def submitBtn(self):
        val_1 = self.entry_1.get()
        val_2 = self.entry_2.get()
        self.sum_var.set(int(val_1) + int(val_2))


class GUI(tk.Tk):

    def __init__(self):    
        super().__init__()
        self.geometry('600x400')
        self.sum_var = tk.IntVar()
        tk.Label(self, text = "Main window").pack()
        tk.Button(self, text= "To enter Data", command=self.spawn_entry_popup).pack()
        sum_label = tk.Label(self, textvariable=self.sum_var)
        sum_label.pack()

    def spawn_entry_popup(self):
        EntryForm(self, self.sum_var)


GUI().mainloop()

来源：https://stackoverflow.com/questions/57215737/how-to-pass-data-between-top-levels-in-tkinter