使用Tkinter标签更改文本的Python参考

Question

I am trying to to change my Tkinter Label text from another function. Somehow I cannot reference the Label and therefore not changing the Label, only add a new on top of the old.

self.errorLabel['text'] = 'second' works inside the init-function of Window, but I need to be able to do it from another function, therefore a reference fault somehow.

This is my code:

import sys
from tkinter import *
from tkinter import ttk

class Window(Frame):

    def __init__(self, master = None):
        Frame.__init__(self, master)
        self.master = master
        self.errorLabel = Label(self, text="some text").grid(row=0)
        self.init_window()

    def init_window(self):
        self.master.title("Example")
        self.pack(fill=BOTH, expand=1)

        goButton = Button(self, text="Go!", command=self.client_go).grid(row=1, column=1)
        quitButton = Button(self, text="Close", command=self.client_exit).grid(row=1, column=0)

    def client_exit(self):
        exit()

    def client_go(self):
        self.errorLabel['text'] = 'second' # TypeError: 'NoneType' object does not support item assignment
        self.errorLabel = Label(self, text="second").grid(row=0)
        return

root = Tk()
root.geometry("800x500")
app = Window(root)
root.mainloop()

Answer 1

This is a very common error with tkinter code. Widget.grid returns None , so when you write:

self.errorLabel = Label(self, text="some text").grid(row=0)

self.errorLabel is None . Instead, create the widget and use it's geometry manager in separate lines of code:

self.errorLabel = Label(self, text="some text")
self.errorLabel.grid(row=0)