如何在填充条目小部件后启用禁用的按钮

Question

我有两个Entry和一个按钮。我想在填写两个Entry之前禁用该按钮的状态。我该如何实现？

howManyStocksLabel = Label(root, text = "How many stocks do you want to evaluate?")
howManyStocksLabel.grid(row = 1, column = 0)
howManyStocksEntry = Entry(root, borderwidth = 3)
howManyStocksEntry.grid(row = 1, column = 1)
riskLabel = Label(root, text = "Enter risk %")
riskLabel.grid(row = 2, column = 0, sticky = 'w')
riskEntry = Entry(root, borderwidth = 3)
riskEntry.grid(row = 2, column = 1)
nextButton = Button(root, text = "Next!", width = 20, height = 2,state = DISABLED,
fg = 'green', bg = 'white',
command= lambda: myClick(riskEntry, howManyStocksEntry, var))
nextButton.grid(row = 4, column = 1)

我试着检查条目是否由填写

if(riskEntry.get() != ""):
....................

但它就是不起作用。

Answer 1

在用户输入值后，您需要检查值是否存在。此外，您可以使用tk.StringVar()作为文本变量并跟踪它。

这里有一个例子：

import tkinter as tk
def check_entry(*args):
if r1.get() and r2.get():
b1.config(state='normal')
else:
b1.config(state='disabled')
root = tk.Tk()
r1 = tk.StringVar(master=root)
r2 = tk.StringVar(master=root)
e1 = tk.Entry(root, textvariable=r1)
e1.pack()
e2 = tk.Entry(root, textvariable=r2)
e2.pack()
b1 = tk.Button(root, text='Click Me!', state='disabled')
b1.pack()
r1.trace('w', check_entry)
r2.trace('w', check_entry)
root.mainloop()

Answer 2

您需要在条目小部件上使用绑定来检查用户是否在条目中输入了任何内容。

每当用户键入其中一个输入框时，此代码将触发check_entry函数：

riskEntry.bind('<KeyRelease>', check_entry)
howManyStocksEntry.bind('<KeyRelease>', check_entry)

那么您的check_entry函数可能如下所示：

def check_entry(event):  #event is required for all functions that use a binding
if riskEntry.get() and howManyStocksEntry.get():
nextButton.config(state=NORMAL)
else:
nextButton.config(state=DISABLED)

Answer 3

实现这一点的一种方法是利用；验证"；Entry窗口小部件支持的内容(请参阅向Entry窗口小部件添加验证)，但要检查多个Entry窗口小部件的内容，并相应地更改Button的状态。

下面展示了如何通过一个助手class来实现这一点，该助手封装了使其相对无痛所需的大部分混乱细节。任意数量的CCD_；观看"；，因此，它可以很好地处理由两个以上条目组成的表单。

from functools import partial
import tkinter as tk
from tkinter.constants import *

class ButtonEnabler:
""" Enable/disable a Button depending on whether all specified Entry widgets
are non-empty (i.e. contain at least one character).
"""
def __init__(self, button, *entries):
self.button = button
self.entries = entries
for entry in self.entries:
func = root.register(partial(self.check_entries, entry))
entry.config(validate="key", validatecommand=(func, '%P'))
def check_entries(self, this_entry, new_value):
other_entries = (entry for entry in self.entries if entry is not this_entry)
all_others_filled = all(entry.get() for entry in other_entries)
combined = bool(new_value) and all_others_filled
self.button.config(state=NORMAL if combined else DISABLED)
return True

root = tk.Tk()
howManyStocksLabel = tk.Label(root, text="How many stocks do you want to evaluate?")
howManyStocksLabel.grid(row=1, column=0)
howManyStocksEntry = tk.Entry(root, borderwidth=3)
howManyStocksEntry.grid(row=1, column=1)
riskLabel = tk.Label(root, text="Enter risk %")
riskLabel.grid(row=2, column=0, sticky='w')
riskEntry = tk.Entry(root, borderwidth=3)
riskEntry.grid(row=2, column=1)
nextButton = tk.Button(root, text="Next!", width=20, height=2, state=DISABLED,
fg='green', bg='white', disabledforeground='light grey',
command=lambda: myClick(riskEntry, howManyStocksEntry, var))
nextButton.grid(row=4, column=1)
enabler = ButtonEnabler(nextButton, howManyStocksEntry, riskEntry)
root.mainloop()