How can I dynamic populate an option widget in tkinter depending on a choice from a drop down menu?

Question

我的问题如下：我有几个文件，我已经创建了一个带有名称的下拉菜单，接下来我需要的是一个选项菜单，只要选择文件名以显示特定文件中的某些数据，就可以更改选项。要清楚，我的问题只是关于如何在选择下拉选项时更改选项菜单。感谢任何帮助。

Answer 1

The OptionMenu widget is nothing more than a convenience class that creates a menubutton that is associated with a menu. You can get at this menu via the "menu" attribute. The only trick is to knowing what the menu items should do, which is nothing more than setting the value of the associated variable.

Here's an example:

import Tkinter as tk

class SampleApp(tk.Tk):
    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        self.om_variable = tk.StringVar(self)

        b1 = tk.Button(self, text="Colors", width=8, command=self.use_colors)
        b2 = tk.Button(self, text="Sizes", width=8, command=self.use_sizes)

        self.om = tk.OptionMenu(self, self.om_variable, ())
        self.om.configure(width=20)
        self.use_colors()

        b1.pack(side="left")
        b2.pack(side="left")
        self.om.pack(side="left", fill="x", expand=True)


    def _reset_option_menu(self, options, index=None):
        '''reset the values in the option menu

        if index is given, set the value of the menu to
        the option at the given index
        '''
        menu = self.om["menu"]
        menu.delete(0, "end")
        for string in options:
            menu.add_command(label=string, 
                             command=lambda value=string:
                                  self.om_variable.set(value))
        if index is not None:
            self.om_variable.set(options[index])

    def use_colors(self):
        '''Switch the option menu to display colors'''
        self._reset_option_menu(["red","orange","green","blue"], 0)

    def use_sizes(self):
        '''Switch the option menu to display sizes'''
        self._reset_option_menu(["x-small", "small", "medium", "large"], 0)

if __name__ == "__main__":
    app = SampleApp()
    app.mainloop()

Answer 2

As the OptionMenu gives a command option, i would suggest to keep reference to the command already given (if any) and pass it to the new options this way:

attendion, variables based on the previous answer

def __init__(self, *args, **kwargs):
    ...
    self.command=kwargs['command']
    ...

def _reset_option_menu(options, index=None):
    ...
    menu.add_command(label=string, 
                     command=lambda:self.command(),
                     value=self.om_variable.set(string))                         
        ...

Hope its of any use Btw, really usefull the answer given by Bryan Oakley,