Python Tkinter传入root实现多窗口跳转时AttributeError问题排查

问题说明 #

尝试用Python Tkinter通过类实现主窗口打开子窗口的功能，采用传入root而非继承tk.Tk的方式。原继承tk.Tk的多窗口示例可正常运行，但改写为传入root的形式后，主窗口能正常打开，点击按钮打开子窗口时触发AttributeError，提示'App' object has no attribute 'tk'。

可正常运行的示例代码 #

import tkinter as tk
from tkinter import ttk


class Window(tk.Toplevel):
    def __init__(self, parent):
        super().__init__(parent)

        self.geometry('300x100')
        self.title('Toplevel Window')

        ttk.Button(self,
                text='Close',
                command=self.destroy).pack(expand=True)


class App(tk.Tk):
    def __init__(self):
        super().__init__()

        self.geometry('300x200')
        self.title('Main Window')

        # 主窗口放置按钮
        ttk.Button(self,
                text='打开窗口',
                command=self.open_window).pack(expand=True)

    def open_window(self):
        window = Window(self)
        window.grab_set()


if __name__ == "__main__":
    app = App()
    app.mainloop()

改写后的错误代码 #

from tkinter import *
from tkinter import ttk


class Window(Toplevel):
    def __init__(self, parent):
        super().__init__(parent)

        self.geometry('300x100')
        self.title('Toplevel Window')

        ttk.Button(self,
                text='Close',
                command=self.destroy).pack(expand=True)


class App():
    def __init__(self, root):
        super().__init__()

        root.geometry('300x200')
        root.title('Main Window')

        # 主窗口放置按钮
        ttk.Button(root,
                text='Open a window',
                command=self.open_window).pack(expand=True)

    def open_window(self):
        window = Window(self)
        window.grab_set()


if __name__ == "__main__":
    root = Tk()
    App(root)
    root.mainloop()

报错信息 #

Traceback (most recent call last):
  File "C:\Users\User\AppData\Local\Programs\Python\Python312\Lib\tkinter\__init__.py", line 1948, in __call__        
    return self.func(*args)
           ^^^^^^^^^^^^^^^^
  File "c:\Users\User\Documents\Python\Python_Tutorial_net\Multiple_Windows_pass-in-Class.py", line 30, in open_window
    window = Window(self)
             ^^^^^^^^^^^^
  File "c:\Users\User\Documents\Python\Python_Tutorial_net\Multiple_Windows_pass-in-Class.py", line 7, in __init__
    super().__init__(parent)
  File "C:\Users\User\AppData\Local\Programs\Python\Python312\Lib\tkinter\__init__.py", line 2678, in __init__
    BaseWidget.__init__(self, master, 'toplevel', cnf, {}, extra)
  File "C:\Users\User\AppData\Local\Programs\Python\Python312\Lib\tkinter\__init__.py", line 2623, in __init__
    self._setup(master, cnf)
  File "C:\Users\User\AppData\Local\Programs\Python\Python312\Lib\tkinter\__init__.py", line 2592, in _setup
    self.tk = master.tk
              ^^^^^^^^^
AttributeError: 'App' object has no attribute 'tk'

解决方案 #

错误原因 #

Window继承自Toplevel，创建实例时需要传入Tkinter窗口对象作为父组件。改写后的App是普通Python类，并非Tkinter窗口实例，传入self（App实例）不符合要求，导致Toplevel无法获取窗口对象的tk属性。

修改后的代码 #

from tkinter import *
from tkinter import ttk


class Window(Toplevel):
    def __init__(self, parent):
        super().__init__(parent)

        self.geometry('300x100')
        self.title('Toplevel Window')

        ttk.Button(self,
                text='Close',
                command=self.destroy).pack(expand=True)


class App():
    def __init__(self, root):
        self.root = root  # 保存root窗口对象的引用
        root.geometry('300x200')
        root.title('Main Window')

        ttk.Button(root,
                text='Open a window',
                command=self.open_window).pack(expand=True)

    def open_window(self):
        # 传入保存的root对象作为父组件
        window = Window(self.root)
        window.grab_set()


if __name__ == "__main__":
    root = Tk()
    App(root)
    root.mainloop()

关键修改点 #

1. 在App的__init__方法中添加self.root = root，保存Tkinter窗口对象的引用；
2. 移除App中无意义的super().__init__()（因为App未继承任何父类）；
3. 在open_window方法中，将Window(self)改为Window(self.root)，传入正确的Tkinter窗口对象作为父组件。

内容的提问来源于stack exchange，提问作者David Collins