在Tkinter应用程序中创建和分配多个变量

Question

My aim is to create 10 dropdown lists (I want to be able to access these values later on) using a for loop to assign each StringVar() and tk.OptionMenu(). However, I am receiving a AttributeError:

'str' object has no attribute 'set'

despite my variables having assigned to them a tkinter.StringVar object:

{'self.comp0': <tkinter.StringVar object at 0x046B9890>, 'self.comp1': <tkinter.StringVar object at 0x0C5E19B0>

code:

from tkinter import OptionMenu
import tkinter as Tkinter
import tkinter.filedialog as tkFileDialog
from tkinter import messagebox as tkMessageBox


class GasGen(Tkinter.Tk):
    def __init__(self,parent):
        Tkinter.Tk.__init__(self,parent)
        self.parent = parent
        self.initialize()
        self.grid()

    def initialize(self):

        vars= {}

        for i in range(8):
            name = "self.comp" + str(i)
            vars[name] = Tkinter.StringVar()

        menus = {}

        for num, i in enumerate(vars):
            names = "menu" + str(num)
            menus[name] = OptionMenu(self, i, "methane", "ethane", "propane", "iso-butane", "n-butane", "iso-pentane", "n-pentane", "benzene").grid(column = 0, row = num)

        print(vars)
        print(".......................")
        print(menus)

if __name__ == "__main__":
    app = GasGen(None)
    app.title('Gas mixture generator')
    app.configure(background = "slate gray")
    app.mainloop()

out:

{'self.comp0': <tkinter.StringVar object at 0x03EA3670>, 'self.comp1': <tkinter.StringVar object at 0x0BB919B0>, 'self.comp2': <tkinter.StringVar object at 0x05045690>, 'self.comp3': <tkinter.StringVar object at 0x0BBE59B0>, 'self.comp4': <tkinter.StringVar object at 0x0BBE5CB0>, 'self.comp5': <tkinter.StringVar object at 0x0BBF54B0>, 'self.comp6': <tkinter.StringVar object at 0x0BBF54F0>, 'self.comp7': <tkinter.StringVar object at 0x0BBF5530>} 

..........................

> {'menu0': None, 'menu1': None, 'menu2': None, 'menu3': None, 'menu4':
> None, 'menu5': None, 'menu6': None, 'menu7': None}

Is this not a good way to assign variables in tkinter? If not, is there a better way to dynamically generate these variables to allow to me set values to their names in the tkinter application?

Answer 1

Your syntax is wrong. The i in OptionMenu(self, i , "methane", "eth... is actually a StringVar() , whose value is set when an Optionmenu is selected. So you need to keep a list of it and initialise the corresponding one.

Here is the working code.

from tkinter import OptionMenu
import tkinter as Tkinter

class GasGen(Tkinter.Tk):
    def __init__(self,parent):
        Tkinter.Tk.__init__(self,parent)
        self.parent = parent
        self.vars = []
        self.initialize()
        self.grid()

    def initialize(self):
        for i in range(8):
            t = Tkinter.StringVar()
            t.set("Not Selected")
            self.vars.append(t)

        for i in range(len(self.vars)):
            OptionMenu(self, self.vars[i], "methane", "ethane", "propane", "iso-butane", "n-butane", "iso-pentane", "n-pentane", "benzene").grid(column = 0, row = i)

        Tkinter.Button(text="Show Values", command=self.show).grid(pady=10)

    def show(self):
        Tkinter.Label(text="\n".join([k.get() for k in self.vars])).grid(pady=10)

if __name__ == "__main__":
    app = GasGen(None)
    app.title('Gas mixture generator')
    app.configure(background = "slate gray")
    app.mainloop()