这是我的问题的后续here https://stackoverflow.com/questions/25194969/more-on-python-tkinter-dynamic-optionmenu/25196500#25196500。我正在尝试使用 ttk.OptionMenu 来增强下拉菜单的外观和感觉。但正如帖子中指出的here https://stackoverflow.com/questions/19138534/tkinter-optionmenu-first-option-vanishes，“ttk optionmenu 小部件以下拉列表中的所有值开始。选择任何值后，列表中的第一个值消失，永远不会重新出现......”该帖子中建议的解决方法是添加一个空项目到列表中。就我而言，因为我使用的是字典，所以添加'':[]因为字典中的第一项解决了问题。这是唯一的解决方案吗？我讨厌将神器引入我的字典。这是代码：
import tkinter as tk
from tkinter import ttk
from tkinter import messagebox
class App:
def __init__(self, master):
master.title("Continental System")
self.dict = {'':[], 'Asia': ['Japan', 'China', 'Malasia'],
'Europe': ['Germany', 'France', 'Switzerland'],
'Africa': ['Nigeria', 'Kenya', 'Ethiopia']}
self.frame1 = ttk.Frame(master)
self.frame1.pack()
self.frame2 = ttk.Frame(master)
self.frame2.pack()
self.variable_a = tk.StringVar()
self.variable_b = tk.StringVar()
self.variable_a.trace('w', self.updateoptions)
self.optionmenu_a = ttk.OptionMenu(self.frame1, self.variable_a, *self.dict.keys())
self.variable_a.set("Asia")
self.optionmenu_a.grid(row = 0, column = 0)
self.optionmenu_b = ttk.OptionMenu(self.frame1, self.variable_b, '')
self.optionmenu_b.grid(row = 0, column = 1)
self.btn = ttk.Button(self.frame2 , text="Submit", width=8, command=self.submit)
self.btn.grid(row=0, column=1, padx=20, pady=20)
def updateoptions(self, *args):
countries = self.dict[self.variable_a.get()]
self.variable_b.set(countries[0])
menu = self.optionmenu_b['menu']
menu.delete(0, 'end')
for country in countries:
menu.add_command(label=country, command=lambda country=country: self.variable_b.set(country))
def submit(self, *args):
var1 = self.variable_a.get()
var2 = self.variable_b.get()
if messagebox.askokcancel("Confirm Selection", "Confirm your selection: " + var1 + ' ' + var2 + ". Do you wish to continue?"):
print(var1, var2)
def set_window(self, *args):
w = 800
h = 500
ws = root.winfo_screenwidth()
hs = root.winfo_screenheight()
x = (ws/2) - (w/2)
y = (hs/2) - (h/2)
root.geometry('%dx%d+%d+%d' % (w, h, x, y))
root = tk.Tk()
app = App(root)
app.set_window()
root.mainloop()
我还收到一些错误消息，包括AttributeError: 'App' object has no attribute 'optionmenu_b'这似乎已在我上面第一个问题的答案中得到解决。
Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Python34\lib\tkinter\__init__.py", line 1487, in __call__
return self.func(*args)
File "C:\Python34\tk1_version2.py", line 32, in updateoptions
menu = self.optionmenu_b['menu']
AttributeError: 'App' object has no attribute 'optionmenu_b'
Python 版本 3.4.1
