Python tkinter 禁用按钮，直到所有字段都填满

问题描述

假设我在 tkinter 中有 2 个条目小部件、1 个选项菜单(下拉列表)和 1 个按钮.在用户填充所有 3 个小部件之前，如何将按钮小部件状态设置为 DISABLED?这是我目前拥有的:

Let's say I have 2 entry widgets, 1 option menu(drop down list) and 1 button in tkinter. How can i set the button widget state to DISABLED until all 3 widgets are filled by the user?This is what i have currently:

import Tkinter as tk

root = tk.Tk()

entry1=tk.Entry(root,width=15).grid(row=1,column=1)
entry2=tk.Entry(root,width=15).grid(row=1,column=2)

choices=('a','b','c')
var=tk.StringVar(root)
option=tk.OptionMenu(root,var,*choices)
option.grid(row=1,column=3)

button=tk.Button(root,text="submit")
button.grid(row=1,column=4)

root.mainloop()

--编辑--

尝试过这种方式，但我认为这不是正确的方式.

Tried this way, but i don't think this is the correct way to do it.

import Tkinter as tk

root = tk.Tk()
def myfunction(event):
    x=var.get()
    y=entry1.get()
    z=entry2.get()
    print len(x),":",len(y),":",len(z)
    if len(y)>0 and len(x)>0 and len(z)>0:
        button.config(state='normal')
    else:
        button.config(state='disabled')
entry1=tk.Entry(root,width=15)
entry1.grid(row=1,column=1)
entry2=tk.Entry(root,width=15)
entry2.grid(row=1,column=2)

choices=('a','b','c')
var=tk.StringVar(root)
option=tk.OptionMenu(root,var,*choices)
option.grid(row=1,column=3)

button=tk.Button(root,text="submit")
button.grid(row=1,column=4)

root.bind("<Enter>", myfunction)
root.mainloop()

推荐答案

Tkinter 变量有一个叫trace 的方法来添加观察者，所以当值改变时会调用回调函数.我认为它比 root.bind("<Enter>", myfunction):

Tkinter variables have a method called trace to add an observer, so the callback function is called when the value changes. I think it is much more efficient than root.bind("<Enter>", myfunction):

import Tkinter as tk

root = tk.Tk()

def myfunction(*args):
    x = var.get()
    y = stringvar1.get()
    z = stringvar2.get()
    if x and y and z:
        button.config(state='normal')
    else:
        button.config(state='disabled')

stringvar1 = tk.StringVar(root)
stringvar2 = tk.StringVar(root)
var = tk.StringVar(root)

stringvar1.trace("w", myfunction)
stringvar2.trace("w", myfunction)
var.trace("w", myfunction)

entry1 = tk.Entry(root, width=15, textvariable=stringvar1)
entry1.grid(row=1,column=1)
entry2 = tk.Entry(root, width=15, textvariable=stringvar2)
entry2.grid(row=1,column=2)

choices = ('a','b','c')
option = tk.OptionMenu(root, var, *choices)
option.grid(row=1,column=3)

button = tk.Button(root,text="submit")
button.grid(row=1, column=4)

root.mainloop()

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