Tkinter用循环创建OptionMenus [英] Tkinter Create OptionMenus With Loop

问题描述

我创建了一个代码，使用for循环在字典中使用值创建tkinter OptionMenus.该代码似乎可以成功运行，并且OptionMenus可以根据需要在窗口中显示关键字...

I have created a code to create tkinter OptionMenus with values in a dictionary using a for loop. The code seems to work successfully, with OptionMenus appearing with keywords on a window as desired...

import tkinter as tk
from tkinter import *

class Example:

    def __init__(self): 
        #Dictionary with categories and their relative keywords
        self.categorykeywords={"Category 1":["Keyword 1", "Keyword 2", "Keyword 3"], "Category 2":["Keyword A","Keyword B","Keyword C"], "Category 3":["Another Keyword"]}

        #Dictionary containing the option menus referenced by category name
        btn_dict={}

        #Storing tkvar variable for later referencing
        self.dropdownreference={}

        #Number to assign to the tkvar name, to make the unique variables for each category
        i=1
        columncounter=0

        for category in self.categorykeywords:
            #Creating a unique variable / name for later reference
            exec('self.tkvar_' + str(i) + ' = ' + 'StringVar(root)') 

            #Creating OptionMenu with unique variable
            btn_dict[category] = tk.OptionMenu(root, exec('variable=self.tkvar_'+str(i)), *self.categorykeywords[category])

            btn_dict[category].grid(row=0, column=columncounter, padx=1, pady=1)

            #Storing the variable used for later use
            self.dropdownreference[category]=exec('variable=self.tkvar_'+str(i)) 

            columncounter+=1
            i+=1

root = Tk()
my_gui = Example()
root.mainloop()

然而，选择它们时，收到一个错误:

However, when they are selected, I receive an error:

Traceback (most recent call last):
  File "c:\users\czuczor\appdata\local\programs\python\python36\lib\tkinter\__init__.py", line 1699, in __call__
    return self.func(*args)
  File "c:\users\czuczor\appdata\local\programs\python\python36\lib\tkinter\__init__.py", line 3434, in __call__
    self.__var.set(self.__value)
AttributeError: 'NoneType' object has no attribute 'set'

我猜想它在实际分配变量时遇到困难，甚至可能只是显示所选的关键字.尝试使用ttk.OptionMenu时会出现相同的错误，它会自动显示第一个值.有关如何解决此问题的任何想法?

I'm guessing it's having trouble actually assigning the variable, or possibly even just displaying the selected keyword. I get the same error when attempting to use ttk.OptionMenu, which automatically displays the first value. Any ideas on how to fix this?

推荐答案

感谢注释，这是通过使用字典而不是exec命令定义变量来解决的问题.

Thanks to the comments, here is the issue solved by using a dictionary to define the variable instead of the exec command.

import tkinter as tk

class Example:

    def __init__(self): 
        #Dictionary with categories and their relative keywords
        self.categorykeywords={"Category 1":["Keyword 1", "Keyword 2", "Keyword 3"], "Category 2":["Keyword A","Keyword B","Keyword C"], "Category 3":["Another Keyword"]}

        #Dictionary containing the option menus referenced by category name
        btn_dict={}

        #Storing tkvar variable for later referencing
        self.dropdownreference={}

        #Number to assign to the tkvar name, to make the unique variables for each category
        i=1
        columncounter=0

        for category in self.categorykeywords:
            #Creating a unique variable / name for later reference
            self.dropdownreference[category] = StringVar(root)

            #Creating OptionMenu with unique variable
            btn_dict[category] = tk.OptionMenu(root, self.dropdownreference[category], *self.categorykeywords[category])

            btn_dict[category].grid(row=0, column=columncounter, padx=1, pady=1)

            columncounter+=1
            i+=1

root = Tk()
my_gui = Example()
root.mainloop()

这篇关于Tkinter用循环创建OptionMenus的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！