我不能使用.get()获取我的Tkinter Checkbutton变量值

问题描述 投票:-5回答:1

所以我一直在研究一个项目,最近我的检查按钮遇到了问题。每当我尝试做variablenname.get()时,它就不会像int value has no attribute get()那样工作。我也确实使用过variablename = IntVar(),我想做的是使if语句依赖于checkbutton的值。

        var = IntVar()
        BTR = Tk()
        Discounts = Checkbutton(BTR, text="Discount (Students, Under 18s, 65+ and Disability Badge Holders)", font = ("times", 30), bg="#252538", fg = "#99FFFF", variable = var)
        Discounts.place(x=120, y=300)
        PriceTag=Label(BTR, text =("£", Cost), font = ("times", 50), fg = "White", bg = "#252538")
        PriceTag.place(x=1000, y= 450)
        val=Label(BTR, text = Tickets, font = ("times", 22), height = 5, width = 15, bg= "White")
        val.place(x=175, y=550)
        add=Button(BTR, text = "+", font = ("times", 22), height = 5, width = 10, bg = "#B266FF", command = lambda: UpdateAdd(val, BTR, PriceTag, BusTicketPrice, price, var))
        add.place(x=420, y=550)

    def UpdateAdd(val, BTR, PriceTag, BusTicketPrice, price, var):
      var = var.get()
      Tickets = Tickets + 1 
      val.destroy()
      val = Label(BTR, text = Tickets, font = ("times", 22), height = 5, width = 15, bg= "White")
      val.place(x=175, y=550)
      PriceTag.destroy()
      if price == "Peak" and var == 0 :
          BusTicketPrice=BusTicketPrice*1.25
      elif var == 1 and price == "Peak":
          BusTicketPrice=BusTicketPrice
      elif var == 1 and price == "Off-Peak":
          BusTicketPrice=BusTicketPrice*0.75
      elif price == "Off-Peak" and var == 0):
          BusTicketPrice=BusTicketPrice
      Cost = BusTicketPrice * Tickets
      Cost = round(Cost, 3)
      PriceTag=Label(BTR, text =("£", str(Cost), "0"), font = ("times", 50), fg = "White", bg = "#252538")
      PriceTag.place(x=1000, y= 450)
python tkinter
1个回答
2
投票

这段代码有几个问题。首先,在创建根窗口并使用Tk()调用启动Tcl解释器之前,不应尝试创建任何Tkinter对象,包括窗口小部件和IntVar。我很惊讶您的代码没有打印出类似的错误消息

AttributeError: 'NoneType' object has no attribute '_root'

因为你在var = IntVar()之前有BTR = Tk()。我没有尝试运行您发布的代码,因为它不是MCVE

你的错误的主要原因是在UpdateAdd你在函数的开头附近做var = var.get()(它从var得到整数值,然后将整数对象绑定到名称var),但是然后再下来你有var.get(),并且这是行不通的,因为现在var指的是整数对象,而不是它最初绑定的IntVar

这是一个最小程序,它演示了使用带有Checkbutton的IntVar可以按预期工作。

import tkinter as tk

BTR = tk.Tk()
var = tk.IntVar()

title = tk.Label(BTR, text="Purchase Bus or Tram Tickets")
title.pack()

discounts = tk.Checkbutton(BTR, text="Discount", variable=var)
discounts.pack()

test = tk.Button(BTR, text="test", command=lambda: print(var.get()))
test.pack()

BTR.mainloop()

按“测试”按钮时,“检查​​”按钮的当前状态将打印到控制台。

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